Multi-Systems Pre-Midterm QStream

Question 1

A 22-year old woman presents to the ED with wheezing, hives, and a sensation that her throat is closing. She has a known peanut allergy, and just ate at a Thai restaurant. Her heart rate is 115 beats/minute, blood pressure is 85/50, respiratory rate is 30 breaths per minute, and her temperature is 98.9 F. She has swelling of her lips and tongue. Which of the following is true regarding epinephrine use in this patient?

• This patient does not have an indication for treatment with epinephrine, and should not receive it
• She should receive an immediate dose of intravenous or intramuscular epinephrine
• She has an absolute contraindication to epinephrine (tachycardia) and should not receive it
• She should receive immediate fluid resuscitation with normal saline, and then epinephrine if her heart rate returns to a normal range

Answer 1

Answer: She should receive an immediate dose of intravenous or intramuscular epinephrine

The patient has anaphylaxis. The most important, appropriate, and immediate treatment is epinephrine.

• She has an absolute contraindication to epinephrine (tachycardia) and should not receive it Incorrect: There are no absolute contraindications to epinephrine use. Tachycardia, especially in a young person, is well tolerated.
• She should receive immediate fluid resuscitation with normal saline, and then epinephrine if her heart rate returns to a normal range Incorrect: Fluid resuscitation is part of the supportive care provided to patients with anaphylaxis, but will not treat her condition. It is not appropriate to delay definitive treatment (epinephrine) for fluid
• This patient does not have an indication for treatment with epinephrine, and should not receive it Incorrect: This patient has anaphylaxis. The treatment is epinephrine.

Question 2

A patient needs a new kidney. After testing a panel of potential donors, the physicians find a “best match” donor. Following transplantation, one of these immunosuppressive drugs will be prescribed: cyclosporine, FK-506, or rapamycin. Although these drugs do not all work by exactly the same mechanism, they have a common effect. This effect is BLOCKING

• the ability of the proteasome to cleave ubiquitinated cytoplasmic proteins.
• the T cell receptor (TCR)-mediated increase in LFA-1 avidity.
• tyrosine phosphorylation of the CD3 ITAMs.
• signaling pathways that stimulate T cell proliferation.
• cell surface expression of CD28 by T cells.

Answer 2

Answer: signaling pathways that stimulate T cell proliferation CORRECT - These drugs block the signaling pathways that activate transcription factors.

• cell surface expression of CD28 by T cells Incorrect - These drugs do not influence cell surface expression of CD28.
• the ability of the proteasome to cleave ubiquitinated cytoplasmic proteins Incorrect -These drugs do not influence proteasome function.
• the T cell receptor (TCR)-mediated increase in LFA-1 avidity Incorrect- These drugs do not influence TCR mediated FFA-1 avidity.
• tyrosine phosphorylation of the CD3 ITAMs Incorrect - These drugs do not influence tyrosine phosphorylation of the CD3 ITAMS.

Question 3

What laboratory test is the most sensitive confirmatory test in SLE?

• Anti-smith antibody
• ANA
• Rheumatoid factor
• CCP

Answer 3

Answer: ANA. ANA is seen in 99+% of patients with SLE and, thus is very sensitive in patients with suspected SLE. It is not, however, specific as it is seen in up to 5% of the general population and its positivity in the general population increases with age.

• CCP Incorrect. CCP is highly specific (>97%) for the diagnosis of rheumatoid arthritis.
• Rheumatoid Factor Incorrect. Rheumatoid factor is sensitive for the diagnosis of rheumatoid arthritis (80%), but less specific. It can be positive in many inflammatory conditions, but is not commonly seen in SLE.
• Anti-smith Antibody Incorrect. Anti-smith antibody is highly specific for a diagnosis of SLE with a specificity of >97%. Its sensitivity however is poor with only 30% of SLE patients having an anti-smith antibody.

Question 4

Multi-drug antimicrobial therapy is often necessary to treat complex infections. In fact, certain combinations of antibiotics such as aminoglycosides and penicillins are synergistic in their actions. However, some antibiotic combinations, for example erythromycin and penicillins, have been observed to have a negative effect on each other’s actions. What is an explanation for the synergistic activity of penicillins and aminoglycosides?

• Aminoglycosides inhibits the synthesis of proteins that are necessary for penicillins to destroy the cell wall.
• Penicillins inhibit cell wall synthesis and destroy the normal binding sites of aminoglycosides.
• Penicillins inhibit cell wall synthesis and facilitate the entry of aminoglycosides into the bacterial cell.
• Aminoglycosides inhibit P450 enzyme activation of penicillins.
• Aminoglycosides cause a misreading of the mRNA, which would normally code for proteins to make the cell wall resistant to the action of penicillins

Answer 4

Answer: Penicillins inhibit cell wall synthesis and facilitate the entry of aminoglycosides into the bacterial cell.

Explanation: Penicillins inhibit cell wall synthesis and facilitate the entry of aminoglycosides into the bacterial cell is correct because aminoglycosides must pass through the cell wall and enter the bacterial cytoplasm to encounter their molecular targets. Penicillins, by inhibiting cell wall synthesis, allow aminoglycosides to more easily enter the bacterium.

Question 5

Many antimicrobials exert their action at sites or within processes that are unique to the DNA replication of prokaryotic cells. This confers a degree of selectivity to these agents, which should limit potential adverse effects in humans. Which of the following statements regarding the selectivity of an antimicrobial drug and its adverse effects is correct?

• Bacterial topoisomerases are structurally different from eukaryotic topoisomerases, contributing to the lack of adverse effects from fluoroquinolones.
• Chloramphenicol inhibits mitochondrial protein synthesis, accounting for its selectivity as an antimicrobial agent.
• Chloramphenicol specifically inhibits bacterial protein synthesis and has a low rate of adverse effects.
• Tetracyclines inhibit both bacterial and mammalian protein synthesis and have a high rate of adverse effects.
• The bacterial RNA polymerase is identical to eukaryotic RNA polymerase, contributing to the high rate of adverse effects associated with rifampin.

Answer 5

Answer: Bacterial topoisomerases are structurally different from eukaryotic topoisomerases, contributing to the lack of adverse effects from fluoroquinolones.

Explanation:

Bacterial topoisomerases are structurally different from eukaryotic topoisomerases, contributing to the lack of adverse effects from fluoroquinolones is the correct answer because Fluoroquinolones target DNA replication of bacteria because of the differences between the machinery required for eukaryotic and prokaryotic DNA replication.

Question 6

A 35 year old female presents with polyarticular joint pain. Synovial fluid analysis shows yellow fluid with 52,000 WBCs/L, 75% of which are polymorphonuclear leukocytes. No crystals or RBCs are noted and the culture is negative. Which of the following is the most likely diagnosis?

• Gout
• Neisseria gonorrhoeae infectious arthritis
• Pigmented villonodular synovitis
• Rheumatoid arthritis
• Osteoarthritis

Answer 6

Answer: Rheumatoid arthitis

Explanation: The synovial fluid analysis is indicative of an inflammatory (Group II) classification of arthritis, of which rheumatoid arthritis is the only example of an inflammatory etiology. Osteoarthritis is noninflammatory ( WBCs < 5,000, PMNs < 30%); PVS is either noninflammatory or hemorrhagic (WBCs < 10,000 with RBCS); Gout is crystal induced; and N. gonorrhoeae is infectious (WBCs > 50,000 with >90% PMNs, RBCs present and positive culture)

Question 7

Which of the following antibiotics can be nephrotoxic?

• Colistin
• All of the answers
• Aminoglycosides
• Penicillins
• Vancomycin

Answer 7

Answer: All of the above.

Explanation: All the answers are correct. Although the classes and mechanisms or targets of action of these drugs are all different, it is important to remember that all have the possibility of causing or exacerbating renal damage.

Bonus:

Colistin- polymixin antibiotic for Gram (-) bacilli, also used as a last resort for multi-drug resistant Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter.

Aminoglycosides- Antibiotic used to treat Gram (-) aerobic bacteria and some Gram (-) anaerobes (most have resistance, though). These drugs inhibit protein synthesis. ex: Streptomycin.

Penicillins- Antibiotic used to treat species of the Streptococci, Staphylococci, Clostridium, and Listeria genera, along w/ Neisseria meningitidis. Penicillin inhibits peptidoglycan crosslinks in bacterial cell walls.

Vancomycin- Antibiotic used to treat C. diff and Staph infections in the intestines (colitis).

Question 8

A 23-year-old male complains of repeated shortness of breath and itchy eyes after mowing his lawn or playing outdoor sports. Suspecting an allergic reaction, his physician injects small quantities of numerous known outdoor allergens beneath his epidermis. The site at which a mixture of grass pollens was injected shows redness and swelling within minutes. An essential mediator of this skin reaction made only by cells of the adaptive immune system is:

• IgE
• Interleukin 8 (IL-8)
• Interleukin 1 (IL-1)
• IgA
• Histamine

Answer 8

Answer: IgE. IgE binds to Fc epsilon receptor on mast cells and basophils.

• Histamine Incorrect – Not made by cells of adaptive immune system; pre-formed mediator.
• IgA Incorrect – This isotypes is not related to hypersensitivity reactions but to mucosal responses.
• Interleukin-1 (IL-1) Incorrect - IL-1 is a cytokine made by macrophages and is pro-inflammatory
• Interleukin-8 (IL-8) Incorrect - Chemokine produced and secreted by macrophages that recruit neutrophils to a site of inflammation

Question 9

A 65 year old female presents for evaluation of color changes in her fingers. She reports 6 weeks of symptoms with her fingers changing color from white to blue upon exposure to cold. In most instances this is followed by pain in her fingers accompanied by redness. She is very active and is the primary caregiver for her 5 grandchildren during the day. Over the past several months she has noted difficulty picking up small objects and the skin on her fingers feels “tight.” Her ROS is otherwise unremarkable. What physical examination finding will be most helpful in distinguishing primary from secondary Raynaud’s phenomenon in this case?

• Nailfold capillaroscopy
• Fundoscopic exam
• Deep tendon reflexes
• Auscultation of the lungs

Answer 9

Answer: Nailfold capillaroscopy

Explanation: Nailfold capillaroscopy is the key exam in the evaluation of Raynaud’s. Primary disease is characterized by normal nailfold capillaries where secondary disease will have dilatation or dropout of these capillaries.

Question 10

A 21 year old native of New York who has just enlisted in the Army receives a Td (Tetanus diphtheria) shot. Which one of the following phrases best characterizes the nature of the soldier’s MOST LIKELY immune response 2 weeks after immunization? He has a

• Secondary response, mainly IgG, against both diphtheria and tetanus toxoid
• Primary immune response, mainly IgG, against both diphtheria and tetanus toxoid
• Primary immune response, exponential phase, mainly IgM against diphtheria and tetanus toxoid.
• Secondary immune response, mainly IgM, against both diphtheria and tetanus
• Primary immune response, mainly IgM, against tetanus toxoid and secondary immune response, mainly IgG, against diphtheria toxoid

Answer 10

Answer: A. Secondary response, mainly IgG, against both diphtheria and tetanus toxoid.

Explanation: This man grew up in the United States and can be presumed to have received a series of childhood vaccinations that would have included DTaP. Thus, he should develop a brisk secondary immune responses against both diphtheria toxoid and tetanus toxoid. Secondary antibody responses to proteins are primarily IgG.

Question 11

The purpose of T cell depletion from donor bone marrow aspirates used in heterologous transplantation is to:

• minimize chances of graft vs. host reaction.
• optimize induction of anti-graft antibodies.
• eliminate tumor antigens.
• eliminate the majority of MHC Class I-positive cells.
• stimulate proliferation of host cytotoxic T lymphocytes (CTL).

Answer 11

Answer: Minimize chances of a graft vs host reaction. Elimination of T cells from the donor decreases the probability of grant reject due to lack of matching at the MHC loci.

• eliminate the majority of MHC Class I-positive cells. Incorrect – MHC class I is expressed on all nucleated cells in the body; elimination would be counterproductive to survival
• eliminate tumor antigens. Incorrect – Not relevant to the elimination of tumor antigens.
• optimize induction of anti-graft antibodies. Incorrect- Would not want to induce antibodies as the graft would be destroyed..
• stimulate proliferation of host cytotoxic T lymphocytes (CTL). Incorrect – Stimulation of host CTL would destroy the graft

Question 12

Vancomycin and teicoplanin are glycopeptide antibiotics that also inhibit cell wall synthesis in bacteria. The difference between these antibiotics and β-lactam antibiotics is

• Glycopeptide antibiotics bind to the D-Ala-D-Ala terminus of the murein monomer, and not to the penicillin binding proteins
• These glycopeptide antibiotics are exclusively effective against Gram negative bacteria.
• The glycopeptide antibiotics have a broader spectrum of activity, inhibiting growth in Gram positive and Gram negative bacteria.
• Glycopeptides are easily transported through the porin channel in Gram negative bacteria.

Answer 12

Answer: Glycopeptide antibiotics bind to the D-Ala-D-Ala terminus of the murein monomer, and not to the penicillin binding proteins.

Explanation: The glycopeptides bind to the tail of the murein at the D-Ala-D-Ala moiety, thus inhibiting crosslinking of the disaccharide precursors. The beta lactam antibiotics bind to the penicillin binding proteins, including to the transpeptidases, inhibiting the enzymes directly.

Question 13

You have just evaluated a patient with a history of various uncommon infections, suggesting immunodeficiency. Testing has ruled out HIV and known immunodeficiencies. Based on a hunch, you have sequenced the B2-microglobulin gene of this patient and found that neither allele encodes a functional protein. This patient would MOST LIKELY exhibit diminished

• IgE responses to helminthic worms.
• killing of intracytoplasmic pathogens.
• antibody neutralization of bacteria.
• phagocytosis of bacteria by macrophages and neutrophils.
• complement lysis of fungal and bacterial pathogens.

Answer 13

Answer: killing of intracytoplasmic pathogens. B2-microglobulin is a critical component of the MHC class I complex. In the absence of MHC class I, CD8+ T cells do not develop in the thymus, resulting in a profound defect in killing of intracytoplasmic pathogens such as viruses.

• antibody neutralization of bacteria Incorrect - b2-microglobulin does not directly influence the development of antibody responses.
• complement lysis of fungal and bacterial pathogens. Incorrect - b2-microglobulin does not influence complement activity.
• IgE responses to helminthic worms. Incorrect - b2-microglobulin plays no role in the development of IgE responses.
• phagocytosis of bacteria by macrophages and neutrophils. Incorrect - b2-microglobulin plays no role in the phagocytosis of bacteria.

Question 14

A serviceman returns from Iraq with a large ulcerated lesion on his forearm caused by Leishmania major, a protozoan parasite that replicates within the phagolysosomes of macrophages. The lesion spontaneously heals over the course of several months, as the macrophages become activated to kill the parasites through interactions with T cells. Which pair of molecules is MOST LIKELY to be responsible for directly activating macrophages?

• CD28 and B7
• TCR and MHC class II
• Fas and Fas-ligand
• CD40 and CD40-ligand
• LFA-1 and ICAM-1

Answer 14

Answer: CD40 and CD40-ligand.

Interaction between CD40 on the macrophage surface and CD40-ligand on the T cell surface confers a potent activating stimulus to the macrophage.

• CD28 and B7 Incorrect – interaction between CD28 on the T cell surface and B7 on the antigen-presenting cell surface provides an important co-stimulatory signal to the T cell, but is not directly responsible for activating macrophages.
• Fas and Fas-ligand Incorrect – interactions between Fas and Fas-ligand are not directly involved in macrophage activation.
• LFA-1 and ICAM-1 Incorrect – LFA-1 and ICAM-1 mediate adhesion between cells but are not directly responsible for macrophage activation.
• TCR and MHC class II Incorrect - engagement of TCR on CD4+ T cells by MHC class II on macrophages must occur for macrophages to be activated by T cells, but this is not the signal directly responsible for macrophage activation.

Question 15

A deficiency in which ONE of the following molecules would most seriously impair an effective and long-lasting antibody response to the measles virus vaccine?

• C3b
• CD40-ligand
• IgE
• CD8
• IL-8

Answer 15

Answer: CD40-ligand.

CD40-ligand on the surface of T helper cells engages CD40 on the surface of B cells. This interaction is critical for stimulation of antibody isotype switching, affinity maturation and the development of memory B cells.

• C3b Incorrect – C3b is a product of complement activation and does not influence the induction of antibody responses.
• CD8 Incorrect – CD8 is not involved in the induction of effective antibody responses.
• IgE Incorrect – IgE is an antibody isotype that does not mediate protection against viral pathogens.
• IL-8 Incorrect – IL-8 is a chemokine that is not directly involved in the induction of antibody responses.

Question 16

A 3-month-old male presents with pneumonia, persistent diaper rash and a failure to thrive. Laboratory tests reveal Pneumocystis carinii infection and persistent cytomegalovirus viremia. Flow cytometric analysis of the patient’s peripheral blood demonstrates an absence of T cells and NK cells, but B cells are detected. A mutation of which X-linked gene would account for this patient’s phenotype?

• γc (common gamma) chain
• IL-7 receptor α chain
• JAK-3 kinase
• RAG-1
• Bruton’s tyrosine kinase (Btk)

Answer 16

Answer: γc (common gamma) chain.

The common gamma chain is a critical component of several cytokine receptors, including the receptors for IL-7 and IL-15. Mutations in the common gamma chain gene, which is located on the X chromosome, results in a profound immuno-deficiency associated with a lack of T and NK cells, which require IL-7 and IL15 for their development, respectively.

• Bruton’s tyrosine kinase (Btk) Incorrect – Btk is required for signaling in B cells, but not in T cells and NK cells
• IL-7 receptor α chain Incorrect – IL-7 receptor alpha chain is a specific component of the IL-7 receptor and is not required for NK cell development. This gene is also not X-linked.
• JAK-3 kinase Incorrect – JAK-3 kinase mediates signals from the common gamma chain and JAK-3 deficiency closely resembles common gamma chain deficiency. However, the JAK-3 kinase gene is autosomal (i.e. not X-linked).
• RAG-1 Incorrect – RAG-1 is a critical component of the VDJ recombinase that is required for the development of both B and T cells. Therefore, a patient with a RAG-1 deficiency would not have B cells.

Question 17

You are sent to sub-Saharan Africa as part of a peace keeping mission following a civil war. In your travels around the region you enter a village reputed to be a “leper colony”. You are surprised to find that very few individuals manifest the extreme disfiguration of lepromatous leprosy, but most of the infected have contained nodular types of infections. The MOST LIKELY reason why the tuberculoid form of leprosy is seen in most of these patients is

• Th1-mediated cellular immunity has controlled the infection
• a strong Th2 cell response has contained the infection
• infection with Mycobacterium tuberculosis is prevalent.
• the cytokines IL-4, IL-5 and IL-10 directed a protective immune response
• they have high levels of circulating antibodies against M. leprae

Answer 17

Answer: Th1-mediated cellular immunity has controlled the infection

Explanation:

Th1 T cells produce interferon gamma, a cytokine that activates macrophages to control intracellular pathogens such as M. leprae, whereas, a Th2 response, driven by Il-4, Il-5 or Il-10 stimulates an antibody mediated response that is not helpful with intracellular pathogens. Mycobacterium TB infection may also be present but does not confer cross-reactive immunity.

Question 18

Which anti-HIV drug is CORRECTLY matched with its mechanism of action?

• fosamprenavir – inhibition of HIV binding to host cells
• ritonavir – inhibition of HIV-encoded integrase
• indinavir – inhibition of HIV-encoded protease
• saquinavir – inhibition of HIV entry into cells
• atazanavir – inhibition of HIV-encoded DNA polymerase

Answer 18

Answer: indinavir – inhibition of HIV-encoded protease

Explanation: Each of the drugs listed above is an inhibitor of the HIV-encoded protease, thus only indinavir is matched with its correct mechanism of action.

Question 19

All of the following statements in the management of an HIV-Infected patient are true EXCEPT:

• Metabolic complications with the use of antiretroviral therapy include: diabetes, hyperlipidemia and lactic acidosis.
• The excellent bioavailability of the fusion inhibitor Fuzeon (T-20, Enfuvirtide) makes it an ideal once a day oral agent.
• Efavirenz, a non-nucleoside reverse transcriptase inhibitor, is a teratogen and should not be used in pregnancy.
• After beginning antiretroviral therapy, the expected reduction in viral load should be at least 1 log in 4 weeks
• A 20 year old patient infected with HIV in 2013 who has access to health care and antiretroviral agents likely has a life expectancy of at least forty years

Answer 19

Answer: The excellent bioavailability of the fusion inhibitor Fuzeon (T-20, Enfuvirtide) makes it an ideal once a day oral agent.

Explanation:

“The excellent bioavailability of the fusion inhibitor Fuzeon (T-20, Enfuvirtide) makes it an ideal once a day oral agent” is FALSE. The fusion inhibitor, Enfuvirtide (T-20, Fuzeon), blocks attachment of HIV at gp41 so targets HIV entry but it is an injectable anti-retroviral and is administered subcutaneously twice a day. There is no oral formulation of this medication.

All other answers are true statements.

Question 20

A 49 year old female presents for follow up of recently diagnosed HIV infection. She feels well and denies any fever, headache, change in vision, cough, shortness of breath, chest pain, abdominal pain, nausea, vomiting, or diarrhea. What lab would order to evaluate whether she needs prophylaxis against any opportunistic infections?

• AFB blood cultures
• No lab evaluation is needed as she is asymptomatic
• CD4 count
• HIV RNA PCR (viral load)
• 3rd generation HIV ELISA

Answer 20

Answer: CD4 count

Explanation:

Persons infected with HIV can be asymptomatic despite having low CD4 counts. In order to determine whether someone needs prophylaxis against opportunistic infections, we evaluate their CD4 count. Normal CD4 counts are around 400 – 500 cells/mm3. When someone’s CD4 count is less than 50 cells/mm3, they are at increased risk for infections with Mycobacterium Avium Complex (MAC), when less than 100 they’re at increased risk of Toxoplasma gondii infection, and when less than 200 they’re at increased risk of Pneumocystis jiroveci infection. HIV RNA levels themselves do not determine risk for opportunistic infections.

Question 21

All of the following are indications to start antiretroviral therapy in an HIV infected patient in 2015 EXCEPT:

• Hepatitis B co-infection, when HBV treatment is indicated
• History of AIDS-defining illness
• HIV associated nephropathy
• Syphilis
• Pregnancy

Answer 21

Answer: Syphilis

Explanation:
A diagnosis of Syphilis does not indicate enhanced risk of disease progression and is not a marker for the need to begin ART. In addition to CD4 cell count, pregnancy, HIV associated nephropathy, Hepatitis co-infection and other AIDS-defining illnesses are all indications to start antiretroviral therapy. While syphilis is an indication to screen for HIV infection, it is not an indication to start anti-retroviral therapy in an HIV infected patient.

Question 22

Based on the information provided and what you know about health disparities, socio-economic status, regional variations in access to care, race, and sexual orientation, which of the following patients is LEAST likely to receive good comprehensive health care?

• Osafo, a recent immigrant of African descent who lives in an urban neighborhood.
• Bill, a middle income Caucasian male who identifies as heterosexual living in a suburban neighborhood.
• Elizabeth, a low income Caucasian woman who identifies as lesbian.
• Justin, a highly educated Latino man who identifies as heterosexual living in a suburban neighborhood.
• Mary, a low income African American woman who is living with a mental disorder in a rural environment.

Answer 22

Answer: Mary, a low income African American woman who is living with a mental disorder in a rural environment.

Explanation: Mary, a low income African American woman who is living with a mental disorder in a rural environment is probably the most disadvantaged of these people in having access to good health care. Being a person of color in a rural envirionment places Mary in an underserved community. Additionally with the mental health needs she would be better served in a more urban environment.

Question 23

Which of the following drugs is commonly used for a patient with PPD skin test conversion?

• Cycloserine
• Linezolid
• Any fluoroquinolone
• Ethionamide
• Isoniazid

Answer 23

Answer: Isoniazid

Explanation:

Isoniazid is the correct answer. Isoniazid is an inhibitor of mycolic acid production in mycobacterium that is used as a first line drug for chemoprophylactic treatment of TB, including patients with PPD skin test conversion, children exposed to risk of infection and patients with a positive PPD who undergo immune suppression (AIDS). The other drugs listed are second line drugs for active infections.

Bonus:

• Cycloserine-Used for TB infections and UTIs
• Linezolid- Used for drug-resistant Gram (+) skin and pneumonia infections. (streptococci, vancomycin-resistant enterococci (VRE), and methicillin-resistant Staphylococcus aureus (MRSA))
• Fluoroquinolones-Broad-spectrum antibiotic used especially for nosocomial and drug-resistant bacterial infections.
• Ethionamide- Antibiotic used to treat active TB

Question 24

You are a Family Practice doc following a 50-year-old man who has been HIV positive for 28 years. He had CD4+ T cell counts well below 200 cells/cumm for several years, was treated for Pneumocystis once, Varicella Zoster twice, and oral Candida albicans too many time to remember. He has had at least two episodes of Haemophilus influenzae and has had anal intraepithelial neoplasia grade 2 (same thing as cervical intraepithlieal neoplasia, except a different anatomic location) treated by a colo-rectal surgeon about 5 years ago. There were only a few scattered condylomata present at his last exam about a year ago. He has been on combination ART since 1995 with excellent control of viral replication, CD4+ T cells have recovered to mid-300s.

Other relevant medical history: Patient has a 40 pack year smoking history, quitting in 1995. He has chronic obstructive pulmonary disease for which he uses an inhaler twice daily. Today he reports a productive cough which developed about 3 months ago. Sputum is white, without blood. He has had no fevers. He has tried the usual over the counter cough suppressants without much effect. He otherwise feels well. A chest x-ray shows a spiculated 2 cm mass in the RUL with associated right hilar adenopathy. What should you be thinking?

• I am going to send the patient for a CT of the chest to better define this lesion. I am worried about lung cancer because of the patient’s long history of chronic immune suppression and history of pulmonary infections associated chronic inflammation.
• Common things being common, I will treat for H flu and see the patient back in 3 months.
• Anal cancer takes a long time to develop. He was treated for grade 2 intraepithelial neoplasia, it is possible he progressed to grade 3 then invasive disease in the year since he saw his colo-rectal surgeon. Now he may have metastatic disease in the lung.
• He hasn’t smoked for 18 years and is only 50, so lung cancer is unlikely. Furthermore, this patient is too fragile for lung cancer chemotherapy.

Answer 24

Answer: I am going to send the patient for a CT of the chest to better define this lesion. I am worried about lung cancer because of the patient’s long history of chronic immune suppression and history of pulmonary infections associated chronic inflammation.

It is best to send the patient for a CT of the chest to better define this lesion.

• To assume that since he hasn’t smoked for 18 years and is only 50, lung cancer is incorrect. Furthermore, even if you assess that this patient is too fragile for lung cancer chemotherapy a correct diagnosis should be pursued. It is CORRECT that lung cancer can develop at an earlier age in HIV infected people. Lung cancer risk never goes away for a smoker, even after 25 yrs of abstinence. Many HIV /AIDS patients do tolerate standard therapies for solid tumors like lung cancer.
• Anal cancer takes a long time to develop. He was treated for grade 2 intraepithelial neoplasia, it is possible he progressed to grade 3 then invasive disease in the year since he saw his colo-rectal surgeon. Now he may have metastatic disease in the lung. INCORRECT It would be unlikely for grade 2 AIN to progress to metastatic disease in one year, especially in a person whose HIV replication is controlled. Furthermore, metastatic disease usually presents as multiple masses on chest x-ray.
• Common things being common, I will treat for H flu and see the patient back in 3 months. INCORRECT This chest x-ray appearance is not consistent with H flu, let alone the fact that the patient otherwise feels well.

Question 25

All of the following statements about opportunistic infections in AIDS are correct EXCEPT: * The wide spread use of antifungal agent (azoles) has decreased the incidence of cryptococcal infections in AIDS patients. * Prophylaxis for MAC has been associated with increased survival in AIDS patients. * CD4 cell mediated immunity protects us from fungi, mycobacterium, viruses and protozoan. * INH (isoniazid) and PZA (pyrazidimine) have been shown to be effective prophylactic agents against MAC. * Both Toxoplasmosis and Primary CNS lymphoma in an AIDS patient can cause ring enhancing brain lesions.

Answer 25

**Answer:** INH (isoniazid) and PZA (pyrazidimine) have been shown to be effective prophylactic agents against MAC. **Explanation:** INH and PZA do not have activity against MAC. They are essential first line drugs in the treatment of MTB. Prophylactic agents for MAC include: the macrolides, azithromycin and clarithromycin or rifabutin. The other statements about AIDS-related infections are true.

Question 26

A 26-year-old male is diagnosed with HIV on routine screening. With use of appropriate anti-retroviral therapy, which of the following malignancies is he still at highest risk of developing? * Bacillary Angiomatosis * Kaposi Sarcoma * Mycosis fungoides * Glioblastoma multiforme * Non-Hodgkin lymphoma

Answer 26

**Answer:** Non-Hodgkin lymphoma **Explanation:** Malignant lymphomas are the most common malignancies secondary to HIV infections. Kaposi sarcoma and Bacillary angiomatosis are HIV associated but the incidence has decreased with anti-retroviral therapy. MF is a T-cell lymphoma which is less likely to be HIV associated, and GBM is not associated with HIV (CNS lymphoma is common).

Question 27

A 25-year-old female with HIV infection, CD4 count 850, viral load \<20 copies/ml comes to your clinic for transition of care after moving to the DC area. She is on an antiretroviral regimen of lopinavir-ritonavir and truvada. Her LDL cholesterol is 120 and her serum triglycerides 750. **What is the LEAST CORRECT response?** * you should refer her for a nutrition consult * you should ask about a family history of hyperlipidemia * you should ask if her blood was collected after fasting * you should not worry that she has any increased risk of coronary vascular disease * you should consider fibrate therapy

Answer 27

**Answer:** you should not worry that she has any increased risk of coronary vascular disease **Explanation:** you should not worry that she has any increased risk of coronary vascular disease is the FALSE answer. You SHOULD be concerned about her potentially increased risk of cardiovascular disease. Fibrate therapy or niacin would be considered for this degree of hypertriglyceridemia especially since HIV itself is considered a risk factor for coronary artery disease. You may also consider switching her to a more modern, less lipid affecting protease inhibitor. TG levels are very sensitive to diet and fasting is important for an interpretable lab value. Nutritional consultation may be useful to control diet. Dyslipidemias may be associated with genetic risk. While not as strongly correlated as elevated LDL cholesterol, high triglycerides are associated with a higher risk of coronary artery disease.

Question 28

Which of the following is most accurate? * The incidence of both peripheral and CNS immunoblastic lymphomas is declining. This is because these lymphomas are caused by KSHV infecting B cells. Modern ART controls KSHV infection. * The best approach for an HIV patient with diffuse large B cell lymphoma, centroblastic type (good prognosis histology) who has a CD4+ T cell count of 450 cells/cumm and suppressed viral replication is to ensure he is taking the best possible combination of ART to gain control of EBV infection. Chemotherapy can be given later if his disease does not respond to ART. * When describing lymphoma in HIV infected persons, you expect extranodal (lymphoma involving organs other than lymph nodes) involvement and early stage (stages I, and II) at presentation. * In considering the spectrum of disease caused by HPV in the cervix, only the early cervical intraepithelial neoplasias (CIN) seem to benefit from modern antiretroviral therapy in terms of regression. Once a high grade lesion or an invasive lesion develop, controlling the HPV infection does not contribute much to regression. By that time the epithelial cells have undergone malignant transformation and are proliferating independently.

Answer 28

**Answer:** In considering the spectrum of disease caused by HPV in the cervix, only the early cervical intraepithelial neoplasias (CIN) seem to benefit from modern antiretroviral therapy in terms of regression. Once a high grade lesion or an invasive lesion develop, controlling the HPV infection does not contribute much to regression. By that time the epithelial cells have undergone malignant transformation and are proliferating independently. * When describing lymphoma in HIV infected persons, you expect extranodal (lymphoma involving organs other than lymph nodes) involvement and early stage (stages I, and II) at presentation. **INCORRECT** We usually see extranodal disease and late stage. * The incidence of both peripheral and CNS immunoblastic lymphomas is declining. This is because these lymphomas are caused by KSHV infecting B cells. Modern ART controls KSHV infection. **INCORRECT** KSHV only causes PEL (primary effusion lymphoma). Immunoblastic lymphomas are EBV. * The best approach for an HIV patient with diffuse large B cell lymphoma, centroblastic type (good prognosis histology) who has a CD4+ T cell count of 450 cells/cumm and suppressed viral replication is to ensure he is taking the best possible combination of ART to gain control of EBV infection. Chemotherapy can be given later if his disease does not respond to ART. **INCORRECT** All HIV associated lymphomas are treated with chemotherapy. Furthermore, only about 50% of centroblastic HIV diffuse large B cell lymphomas are EBV positive so controlling EBV infection is not especially important in this disease.

Question 29

A 37 year old woman with severe neutropenia due to chemotherapy develops fevers associated with a left lower lobe pulmonary infiltrate. Due to progression of the disease despite broad-spectrum antibacterial and antifungal treatment, her left lower lung is biopsied by video-assisted thoracoscopic surgery. Which of the following fungi is most likely to be seen on lung biopsy? (A-E in attached image).

Answer 29

**Answer:** B **Explanation:** Aspergillus is the most common fungal cause of pulmonary infiltrates in patients who develop neutropenia during chemotherapy. Aspergillus grows as a mold in tissue (specifically within blood vessels) with hyphae that exhibit *acute angle branching* as seen in panel B.

Question 30

You are a 4th (year) medical student on an OB/GYN rotation. You are scrubbed in on a routine cesarean section. Your attending offers for you to assist in closing the surgical incision. As you are suturing you hold the needle driver in your right hand. Your hand slips and you puncture your left pointer finger, breaking the glove and your skin. What is the next most appropriate step: * Stop what you are doing and report to the Emergency Room for Post Exposure Prophylaxis * Inform your attending and break scrub to irrigate the puncture site * Continue closing the surgical incision and discuss with your attending afterwards * Continue closing the surgical incision and double check the patient’s HIV status after the procedure

Answer 30

**Answer:** Inform your attending and break scrub to irrigate the puncture site **Explanation:** The very first step with a needlestick injury is to quickly and thoroughly clean the puncture area. Since the attending is right there, let him/her know what has happened. You will then go to the Occupational Health office or the emergency room (as specified by your hospital operating procedure). They will attend to you, document the incident, and investigate the risk of exposure associated with this patient. No prophylaxis may be necessary.

Question 31

An obstetrician examines an infant who was infected in utero with a virus that now has an ocular manifestation of the viral disease (see figure). The child’s mother was not vaccinated against the virus when she was a child. Which vaccine would have been beneficial to the infant? * A subunit vaccine composed of the protective viral antigen. * A vaccine given on the same schedule as a poliovirus vaccine * A vaccine given on the same schedule as the measles vaccine. * A vaccine made of a carbohydrate attached to a carrier protein. * A vaccine made of the formalin-inactivated whole virus.

Answer 31

**Answer:** A vaccine given on the same schedule as the measles vaccine **Explanation:** This is *rubella virus (*a togovirus); the clues here are infection in utero and the clinician notes the cataract in the infant’s eye which is a classic manifestation of the pathology rubella virus can cause because it is highly teratogenic. When rubella virus infects a women during the first trimester of pregnancy there is a high probability that the baby will suffer congenital abnormalities notably: deafness, blindness-cataracts, heart or brain defects. The live attenuated rubella virus vaccine is given with the live attenuated measles and mumps vaccines (the MMR vaccine).

Question 32

An 11-year-old girl was sent home from school due to pain and swelling in the parotid region (surrounding her jaw) that she experienced while eating lunch, and she also complained of a headache and had a low-grade fever. The swelling of the glands increased in 2 to 3 days while she remained home. The child had not received all recommended vaccinations. The teacher indicated that another student in the same class had presented similar complaints three weeks earlier. The disease was diagnosed as * Hepatitis A * Measles * Influenza A * Mumps * Rubella

Answer 32

**Answer:** Mumps **Explanation:** This is mumps virus (a paramyxovirus); the most important clue here is the pain and swelling in the parotid region and her age; then also noting the disease course of increased swelling along with fever and headache and fact that she did not receive all recommended vaccinations along with the report of another student with similar symptoms. The MMR vaccine consists of the live-attenuated measles, mumps and rubella viruses. Although there are vaccines for all the viruses listed, only mumps virus presents with these classic symptoms.

Question 33

General S., a 55 year old male, recently completed War College where he was told that he should always get a PSA every year in order to do his best to prevent Prostate CA. He presents to you requesting a PSA as part of the face-to-face interview after completing the survey part of his annual PHA. Your most appropriate response would be to: * Order the PSA, perform a digital rectal exam, and order a flexible sigmoidoscopy in AHLTA after the General leaves your office * Refer him to Urology * Order the PSA * Order the PSA and perform a digital rectal exam * Discuss the risks and benefits of PSA screening, including the current D recommendation from the USPSTF against screening

Answer 33

**Answer:** Discuss the risks and benefits of PSA screening, including the current D recommendation from the USPSTF against screening **Explanation:** The specific USPSTF (2012) recommendation for screening for Prostate CA is as follows: “The USPSTF recommends against PSA-based screening for prostate cancer.” It is a “D” recommendation: “The USPSTF recommends against the service. There is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits.” In addition to knowing the appropriate recommendations, it is also important to convey to the patient the rationale to not perform a test that has weak predictive value and may even have a negative impact on the patient.

Question 34

Which of the following Hazards are associated with a Medical Treatment facility? * Anesthetic Gases * Noise * Violence * All of the answers * Radiation

Answer 34

**Answer:** All of the answers **Explanation:** Physical Hazards in a medical center include workplace violence, noise, heat, lasers, and ionizing radiation. Chemical Hazards include anesthetic gases, medications (notably chemotherapeutics), glutaraldehyde, formaldehyde and ethylene oxide. Psychological Hazards include work stress, organizational factors which include staffing, turnover and shift work. Biological hazards are numerous and include the infectious diseases as well as allergens.

Question 35

Several nearly empty, leaking drums containing a toxic chemical were discovered at an abandoned industrial site. The soil near the drums is heavily stained with a strong odor. Many homes near the site use private wells for their drinking water. Testing of the well water revealed trace amounts of the same chemical found in the drums. Which of the following courses of action would be the most likely to eliminate this exposure pathway * Install a fence at the industrial site to prevent children from contacting the soil. * Provide bottled water for the residents. * Monitor indoor air quality in the affected homes. * Remove the drums from the industrial site.

Answer 35

**Answer:** Provide bottled water for the residents. Drinking water from the wells is the point of exposure so having residents drink bottled water eliminates the completed pathway. * Remove the drums from the industrial site is **INCORRECT**. The chemical has already leaked into the ground so removing the drums will not prevent the contamination from moving from the soil into the groundwater. * Install a fence at the industrial site to prevent children from contacting the soil. **INCORRECT.** The pathway does not involve dermal contact with the contaminated soil. * Monitor indoor air quality in the affected homes. **INCORRECT**. The pathway does not involve inhalation of contaminated air.

Question 36

Which Federal Agency sets legally enforceable Occupational Permissible Exposure Limits (PEL)? * Department of Labor * Department of Health and Human Services * Department of Defense * Department of Transportation

Answer 36

**Answer:** Department of Labor **Explanation:** Occupational Safety and Health Administration (OSHA) as established as part of the Occupational Safety and Health Act of 1970 as part of the Department of Labor. Its mission is to assure safe and healthful working conditions for working men and women by setting and enforcing standards and by providing training, outreach, education and assistance.

Question 37

For which of the following exposure do you not need to seek attention from Occupational Health Clinic? * Active duty Patient on Behavioral Health unit spits in your eye and you spill a bed pan full of urine on your leg while trying to help a nurse move a patient * Needlestick breaking your skin while starting an IV * Active duty Patient on Behavioral Health unit spits in your eye * Active duty Patient in ER pulls out IV and blood splatters in your mouth * You spill a bed pan full of urine on your leg while trying to help a nurse move a patient * None of the Answers

Answer 37

**Answer:** None of the Answers **Explanation:** The immediate steps after an exposure are: - Wash needlesticks and cuts with soap and warm water - Flush splashes to the nose, mouth, or skin with water - Irrigate eyes with clean water, saline, or sterile irrigants - Report incident to supervisor - Immediately seek medical treatment As a Health Care Worker, you should seek evaluation from the Occupational Health Clinic anytime you are exposed to blood or body fluids. It is important to report the nature of the exposure and have the source’s identifying information. Occupational Medicine along with Infectious Disease specialists can then determine the extent of the evaluation and if any treatment is warranted. It is also important to have the exposure documented in your health record.

Question 38

A 32-year-old respiratory therapy technician from the Philippines develops a skin reaction to her annual PPD test of 15 mm. She had no induration following the PPD test given in last year’s screening. The appropriate response to this finding is: * Order cultures and smear for acid-fast bacilli. * Consider the test to be negative given this employee’s job and demographics. * Determine whether she had received the BCG vaccine previously that may lead to a false positive. * Order a chest X-ray and assess whether she has evidence of a current TB infection. * Wait 6 months and retest the PPD

Answer 38

**Answer:** Order a chest X-ray and assess whether she has evidence of a current TB infection. **Explanation:** It is best to assess whether this person has evidence of pulmonary TB. She is at elevated risk due to her occupation and foreign birth. The BCG may give a false positive result but her prior test was negative so this appears to be a conversion to reactive state. It is unlikely she would be shedding AFB if she is otherwise asymptomatic so culture and smear are unlikely to be useful.

Question 39

Occupational Medicine Programs include which of the following EXCEPT: * Coordination with Industrial Hygiene, Safety and Audiology * Coordination with Industrial Hygiene, Safety and Audiology and Medical Surveillance * Medical Surveillance * Primary Care Services

Answer 39

**Answer:** Primary Care Services **Explanation:** Occupational Health Teams work closely with **Industrial Hygiene** and **Safety** to assure a safe work environment. **Audiology** works with Occupational Health in support of hearing conservation programs. Employees exposed to work place hazards are enrolled in **medical surveillance** programs. **Primary care services** are not offered as part of a typical Occupational Medicine Program.

Question 40

Which of the following is not a competency of an Occupational and Environmental Medicine Physician? * Health and Productivity * Disaster Preparedness and Emergency Management * Hazard Recognition/Evaluation and Control * All of the answers are competencies * Determining Fitness for Duty

Answer 40

**Answer:** All of the answers are competencies **Explanation:** The 10 Core Competencies in Occupational and Environmental Medicine include: 1. Clinical Occupational and Environmental Medicine 2. OEM Related Law and Regulations 3. Environmental Health 4. Work Fitness and Disability Integration 5. Toxicology 6. Hazard Recognition, Evaluation, and Control 7. Disaster Preparedness and Emergency Management 8. Health and Productivity 9. Public Health, Surveillance, and Disease Prevention 10. OEM Related Management and Administration

Question 41

A 22-year old woman presents to the ED with wheezing, hives, and a sensation that her throat is closing. She has a known peanut allergy, and just ate at a Thai restaurant. Her heart rate is 115 beats/minute, blood pressure is 85/50, respiratory rate is 30 breaths per minute, and her temperature is 98.9 F. She has swelling of her lips and tongue. Which of the following is true regarding epinephrine use in this patient? * She should receive an immediate dose of intravenous or intramuscular epinephrine * She has an absolute contraindication to epinephrine (tachycardia) and should not receive it * She should receive immediate fluid resuscitation with normal saline, and then epinephrine if her heart rate returns to a normal range * This patient does not have an indication for treatment with epinephrine, and should not receive it

Answer 41

**Answer:** She should receive an immediate dose of intravenous or intramuscular epinephrine. The patient has anaphylaxis. The most important, appropriate, and immediate treatment is epinephrine. * She has an absolute contraindication to epinephrine (tachycardia) and should not receive it **Incorrect:** There are no absolute contraindications to epinephrine use. Tachycardia, especially in a young person, is well tolerated. * She should receive immediate fluid resuscitation with normal saline, and then epinephrine if her heart rate returns to a normal range **Incorrect:** Fluid resuscitation is part of the supportive care provided to patients with anaphylaxis, but will not treat her condition. It is not appropriate to delay definitive treatment (epinephrine) for fluid * This patient does not have an indication for treatment with epinephrine, and should not receive it **Incorrect:** This patient has anaphylaxis. The treatment is epinephrine.

Question 42

A 65 year old female presents for evaluation of color changes in her fingers. She reports 6 weeks of symptoms with her fingers changing color from white to blue upon exposure to cold. In most instances this is followed by pain in her fingers accompanied by redness. She is very active and is the primary caregiver for her 5 grandchildren during the day. Over the past several months she has noted difficulty picking up small objects and the skin on her fingers feels “tight.” Her ROS is otherwise unremarkable. What physical examination finding will be most helpful in distinguishing primary from secondary Raynaud’s phenomenon in this case? * Auscultation of the lungs * Fundoscopic exam * Nailfold capillaroscopy * Deep tendon reflexes

Answer 42

**Answer:** Nailfold capillaroscopy is the key exam in the evaluation of Raynaud’s. Primary disease is characterized by normal nailfold capillaries where secondary disease will have dilatation or dropout of these capillaries.

Question 43

You have just evaluated a patient with a history of various uncommon infections, suggesting immunodeficiency. Testing has ruled out HIV and known immunodeficiencies. Based on a hunch, you have sequenced the B2-microglobulin gene of this patient and found that neither allele encodes a functional protein. This patient would MOST LIKELY exhibit diminished * antibody neutralization of bacteria. * complement lysis of fungal and bacterial pathogens. * IgE responses to helminthic worms. * killing of intracytoplasmic pathogens. * phagocytosis of bacteria by macrophages and neutrophils.

Answer 43

**Answer:** killing of intracytoplasmic pathogens. b2-microglobulin is a critical component of the MHC class I complex. In the absence of MHC class I, CD8+ T cells do not develop in the thymus, resulting in a profound defect in killing of intracytoplasmic pathogens such as viruses. * antibody neutralization of bacteria **Incorrect** - b2-microglobulin does not directly influence the development of antibody responses. * complement lysis of fungal and bacterial pathogens. **Incorrect** - b2-microglobulin does not influence complement activity. * IgE responses to helminthic worms. **Incorrect** - b2-microglobulin plays no role in the development of IgE responses. * phagocytosis of bacteria by macrophages and neutrophils. **Incorrect** - b2-microglobulin plays no role in the phagocytosis of bacteria.

Question 44

A 38-year-old female undergoing radiation treatment for breast cancer is suspected of an accidental exposure to several thousand roentgens of radiation due to operator error. Which of her following tissues will be most radioresistant to injury? * Ovaries * Breast tissue * Brain * Bone marrow * Gastrointestinal tract

Answer 44

**Answer:** Brain. Of the tissues listed, the brain would be the most resistant to radiation (See Robbins f. 9-19, p. 424)

Question 45

There is an outbreak of illness involving five children from three families in a communal home school. The majority of the children in the households have not been immunized due to parental beliefs. One family has several college aged children, one of whom recently returned from a semester abroad. The affected children all have a fever; a blotchy maculopapular rash on their face, trunk and extremities; and white spots on their oral mucosa. Which of the following is correct regarding the route of transmission of this disease? * Fecal oral * Respiratory droplets * Direct contact with vesicles * Sexually transmitted; authorities should be notified of suspected abuse * Food borne, likely from common source of food preparation

Answer 45

**Answer:** Respiratory droplets The disease that is described is Measles. It is highly contagious and is spread by respiratory droplets.

Question 46

An 86-year-old African American male with history of coronary artery disease, hypertension, hyperlipidemia, diabetes, osteoarthritis, gout and recurrent falls presented to the clinic with his wife. He ambulates with a walker. You watch him entering the examination room with slow gait. He talks slow and in a low volume. His wife told you that he has lost some weight since his last visit 6 months ago and has fallen about 2-3 times during this time period. He needs assistance from his wife in bathing and dressing. He spends most of his day lying in bed or sitting in a chair. How do you describe this Elderly male? * In excellent health * May live 20 more years * Prefrail * Frail * Can live independently

Answer 46

**Answer:** Frail Frail person – this patient meets most of the criteria which are – weight loss, slow walking speed, decreased energy, low calorie burn out and decreased strength. Frail patients have life expectancy limited to 2-4 years. * In excellent health **Incorrect** – He is in poor health he has many health problems, recurrent falls and needs assistance from his primary care giver. * May live 20 more years **Incorrect** Based on his personal health, multiple morbidities and dependence, frailty - his life expectancy is limited. * Prefrail **Incorrect** - Prefrail person can live independently and do not have weight loss. * Can live independly **Incorrect** – He cannot live independently due to marked functional decline

Question 47

A 5-month-old boy is brought to the emergency department by his mother because of decreased activity and vomiting for 1 day. She reports occasional foul-smelling stools but no recent changes in stool pattern. There has been no fever. As a neonate, the boy had difficulty gaining weight and prolonged jaundice, but he has not required hospitalization. Physical examination reveals an ill-appearing child who has mild dehydration, a heart rate of 120 beats/min, and otherwise normal vital signs. He appears somewhat cachectic, and his weight is at the 3rd percentile. Laboratory values include a normal complete blood count and urinalysis, sodium of 134.0 mEq/L (134.0 mmol/L), chloride of 86.0 mEq/L (86.0 mmol/L), potassium of 3.8 mEq/L (3.8 mmol/L), and carbon dioxide of 31.0 mEq/L (31.0 mmol/L). Blood urea nitrogen and creatinine values are within normal limits. Of the following, the MOST likely diagnosis is * Bartter syndrome * Congenital adrenal hyperplasia * Cystic fibrosis * Fanconi syndrome * Hypertrophic pyloric stenosis

Answer 47

**Answer:** Cystic fibrosis **Explanation:** Cystic fibrosis is an autosomal recessive disorder affecting many children and adolescents. It is caused by a defect in a chloride channel, the cystic fibrosis transmembrane conductance regulator (CFTR), on the apical membranes of the linings of the airways, intestinal tract, vas deferens, biliary tree, pancreatic ducts, and sweat ducts. The result is ineffective secretion of fluids from affected areas and an increased sodium and chloride sweat concentration, the latter being the basis for diagnostic testing. Affected children have varying degrees of mucoid airway obstruction, with secondary bacterial infections, failure to thrive, intestinal obstruction, pancreatic and biliary dysfunction, and infertility. Hypochloremic metabolic alkalosis with dehydration, as described for the boy in the vignette, is a common feature because of the high salt loss from the sweat glands. Foul-smelling stools, prolonged jaundice, and poor weight gain are additional features of the disease. Therefore, the boy in the vignette should undergo testing for cystic fibrosis (eg, sweat chloride testing and genetics testing). Bartter syndrome results from a defect in chloride reabsorption in the loop of Henle. Clinical features include failure to thrive, polyuria, and vomiting. Hypochloremia and metabolic alkalosis can occur, but hypokalemia, which can be severe, is usual and due to urinary potassium wasting. Infants who have the salt-losing form of congenital adrenal hyperplasia also may present with vomiting and failure to thrive, but typical electrolyte abnormalities are hyponatremia, hypochloremia, and hyperkalemia. Fanconi syndrome is characterized by abnormal proximal renal tubule function. Excessive bicarbonaturia causes metabolic acidosis with hyperchloremia, and hypokalemia may be seen. Clinical features in infancy can be similar to those of the previously described diseases, with failure to thrive, vomiting, and polyuria being common. Infants who have hypertrophic pyloric stenosis often have hypochloremic metabolic alkalosis, but this condition is seen in younger infants and is the result of substantial vomiting of a long duration. References: - Boat TF, Acton JD. Cystic fibrosis. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:1803-1816 - Davis PB. Cystic fibrosis. Pediatr Rev. 2001;22:257-264. Available at: http://pedsinreview.aappublications.org/cgi/content/full/22/8/257

Question 48

Pulmonary infections are common among patients with cystic fibrosis, so therapy generally should be directed against which of the following organisms: * Pseudomonas aeruginosa * Chlamydia pneumoniae * Moraxella catarhallis * Streptococcus pneumoniae

Answer 48

**Answer:** Pseudomonas aeruginosa **Explanation:** Nearly all cystic fibrosis patients become colonized with Pseudomonas aeruginosa by the age of 18 to 20. This organism is particularly problematic because it readily forms biofilms through the elaboration of a sticky alginate capsule that interacts with the sticky mucus in the CF patient's airways to form a biofilm. Additionally, Pseudomonas is relatively resistant to antibiotics. The other organisms are pathogens in the upper and or lower respiratory tract but are not specifically related to CF.

Question 49

You are seeing a 2-year-old girl for constipation of a few weeks’ duration. On physical examination, her height is at the 25th percentile for age, her weight is at the 5th percentile, she has mild abdominal distention, and you palpate a tubular mass in the left lower quadrant. You recommend treatment with a polyethylene glycol-containing laxative and arrange for a follow-up appointment in 2 weeks. After 1 week, her mother calls to tell you that her stools are softer, but that the girl has experienced three episodes of "something like her intestines" protruding from her rectum after a bowel movement. Further, although her stools are softer, she continues to pass large-caliber stools with some "straining." Of the following, the MOST important test to obtain in further evaluating this child is * tissue transglutaminase antibody measurement * barium enema * sweat chloride * stool for ova and parasites * abdominal ultrasonography

Answer 49

**Answer:** sweat chloride **Explanation:** Sweat Chloride is the correct answer because rectal prolapse involves the intussusception and exteriorization of rectal tissue. Prolapsed tissue may contain only the rectal mucosa or all tissue layers (mucosa, submucosa, and muscularis) may be exposed. Overall, rectal prolapse is most common between 1 and 5 years of age, with a mean incidence age of 3 years. It is a well-described complication in young children being treated for constipation. In fact, available evidence indicates that functional constipation, in the absence of any underlying anatomic or metabolic disorder, is the most common cause of rectal prolapse in childhood, accounting for up to 30% of cases. Although the presentation described for the girl in the vignette appears to be relatively typical, two "red flags" should point the astute clinician to an alternate explanation for this problem. First, the child’s growth percentiles demonstrate a significant height/weight discrepancy. By itself, in the absence of prior growth data and family history, this is not necessarily an alarming finding, but the second factor is that several episodes of prolapse have occurred following the production a soft stool.Accordingly, a high index of suspicion in this and in all cases of recurrent rectal prolapse in childhood must be given to cystic fibrosis (CF). Therefore, a sweat chloride test is the most important study to obtain for this patient. Ruling out CF in this setting is of particular importance because it represents a common heritable disorder in the United States, with a gene frequency of approximately 1:29 in the white population. Overall incidence figures indicate that CF affects approximately 1 in 3,500 children of Caucasian descent, with the incidence in other populations of approximately 1 in 11,500 (Hispanics), 1 in 20,000 (African Americans) and 1 in 90,000 (Asians). CF accounts for approximately 10% of all reported cases of rectal prolapse during infancy and early childhood. Collected case series suggest that rectal prolapse occurs in 20% of patients who have CF between the ages of 6 months and 3 years, and it may be the presenting sign of disease for many patients. When prolapse occurs in infants younger than 1 year of age, the likelihood of an underlying CF diagnosis is even higher. Other diagnostic possibilities for rectal prolapse include acute diarrhea and neuromotor and connective tissue disorders (especially Ehlers-Danlos syndrome); up to 20% of patients have no identifiable cause. Rectal prolapse is a potential complication for any child who has an acute or chronic diarrheal illness, including intestinal infections and malabsorptive disorders. Heavy parasitic infestations of enterobiasis (pinworm), amebiasis, and trichuriasis (whipworm, a rare infection in the United States) have been associated with rectal prolapse. Therefore, examining stool for ova and parasites may be indicated in selected cases. Celiac disease should be considered (tissue transglutaminase antibody measurement) in any child who exhibits poor weight gain and bulky stools, but rectal prolapse has not been reported to be a common complication in affected patients. Hirschsprung disease rarely has been reported as a cause of prolapse, but the constipation of only several weeks’ duration and the spontaneous passage of soft stools following oral polyethylene glycol therapy make such a diagnosis unlikely for this child. Therefore, a barium enema examination is not indicated. Finally, abdominal ultrasonography generally is not helpful in the evaluation of constipation or rectal prolapse.

Question 50

A 14-year-old boy who has cystic fibrosis presents with an acute pulmonary exacerbation involving tachypnea, chest wall retractions, and decreased oxygen saturation from baseline. You order a sputum culture. Of the following, the MOST appropriate choice for empiric antimicrobial therapy pending the culture results is * azithromycin and cefuroxime * clindamycin and cefotaxime * vancomycin * trimethoprim-sulfamethoxazole * piperacillin/tazobactam and gentamicin

Answer 50

**Answer:** piperacillin/tazobactam and gentamicin **Explanation:** Piperacillin/tazobactam and gentamicin is the correct answer because Cystic fibrosis (CF) is an inherited disorder characterized by a defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that leads to production of thick, viscous mucus and recurrent severe pulmonary infections. Although initial pulmonary infections have been associated with Staphylococcus aureus in patients who have CF, beyond 1 to 2 years of age, Pseudomonas can be isolated. Over time, the organism persists and transitions to a mucoid phenotype that is associated with progressive deterioration in pulmonary function and intermittent acute deteriorations. Therefore, empiric therapy of a pulmonary exacerbation of CF, as described for the boy in the vignette, must include coverage for Pseudomonas, such as the combination of piperacillin/tazobactam and gentamicin. The combination of azithromycin and cefuroxime provides excellent coverage for the usual bacterial pathogens (primarilypneumococcus and mycoplasma) seen in pneumonia in otherwise healthy hosts at this age.Clindamycin and cefotaxime might be considered in the severely ill child who has pneumonia that potentially is caused by penicillin-resistant pneumococci, staphylococci, and Haemophilus.Trimethoprim-sulfamethoxazole does not have significant activity against Pseudomonas or pneumococcus, making it an inadequate choice for this patient or an otherwise healthy person who has bacterial pneumonia. Vancomycin only has activity against gram-positive organisms. Ciprofloxacin and possibly levofloxacin are the only quinolones that have significant antipseudomonal activity. Ciprofloxacin has been used as an oral alternative in pulmonary exacerbations for those who have CF. Carbapenems (imipenem and meropenem) and ceftazidime are other antipseudomonal antibiotics that might be considered for treatment in this setting. Isolates should be processed for antimicrobial sensitivities because resistance can occur to even the previously mentioned antipseudomonal antibiotics. P aeruginosa is a gram-negative organism that is common in the environment. It even can be cultured from distilled water. Infections in immunocompetent hosts are rare, although Pseudomonas has been associated with hot tub folliculitis and ocular infections from contaminated contact lens solution. Pseudomonas also can be isolated in necrotic cartilage frompatients who have puncture wound osteomyelitis. In immunocompromised patients, Pseudomonas can cause sepsis or ecthyma gangrenosum. It also has been associated with hospital-acquired infections in debilitated patients, such as ventilator-associated pneumonia or infections in burn patients. In these settings, the infection is due to direct invasion by the organism and related bacterial virulence factors. The host’s inflammatory response to the organism and decreased mucociliary clearance in CF appear to be critical in the pathophysiology of pneumonia in this condition.

Question 51

A 9-year-old boy who has cystic fibrosis (delta-F508 homozygous) presents with a complaint of abdominal pain. He reports that he has had two to three small bowel movements per week over the past few weeks. Six months ago, because of problems with weight gain, you had increased his dosage of oral pancreatic enzymes to 50,000 lipase units per meal and 10,000 lipase units per snack. On physical examination, he weighs 25 kg, appears uncomfortable, and has moderate abdominal distention and a palpable right-sided abdominal mass. Of the following, the MOST likely diagnosis is *

Answer 51

**Answer:** distal intestinal obstruction syndrome **Explanation:** Distal Intestinal Obstruction syndrome is the correct answer. Distal intestinal obstruction syndrome (DIOS), formerly referred to as meconium ileus equivalent, is a common gastrointestinal complication in patients who have cystic fibrosis (CF). It is of particular concern among those for whom intestinal maldigestion/malabsorption, a problem that invariably is associated with the delta-F508 homozygous state, remains poorly controlled. DIOS is suggested for the boy in the vignette by the findings of decompensated malabsorption, constipation, and abdominal discomfort and distention. The physical finding of a right-sided abdominal mass further supports this diagnosis. CF is the most common heritable disorder among whites in the United States, with a gene frequency of approximately 1 in 29 in this population. Overall incidence figures indicate that CF affects approximately 1 in 3,500 children of Caucasian descent, with the incidence in other populations of approximately 1 in 11,500 (Hispanics), 1 in 20,000 (African Americans) and 1 in 90,000 (Asians). It is transmitted in an autosomal recessive pattern, with heterozygotes being unaffected. Although more than 2,000 CF gene mutations have been described, approximately 70% of CF alleles in the United States demonstrate the delta-F508 mutation on chromosome 7, where a phenylalanine residue is deleted at position 508 of a 1,480-amino acid protein. Approximately 50% of CF patients are homozygous for this mutation, which is associated with severe disease. The consequent metabolic defect involves mutation in the cystic fibrosis transmembrane conductance regulator (CFTR), resulting in abnormal chloride and water secretion across epithelial surfaces of all exocrine organs. This causes abnormally thick and viscid secretions, leading to dysfunction in multiple systems, including the lung, liver, pancreas, and gastrointestinal tract. DIOS results from inspissation of viscous mucus and fecal material in the ileum, cecum, and ascending colon. It is a relatively common problem in CF, reported in 10% to 20% of patients. DIOS occurs with greatest frequency in older children and adolescents. Predisposing factors (apart from the primary CFTR defect) include poorly controlled fat malabsorption, previous meconium ileus, low dietary fiber intake, and possibly prolonged intestinal transit time. Interestingly, although DIOS has been reported in CF patients who retain relatively normal pancreatic exocrine function, the syndrome has not been reported in other forms of pancreatic insufficiency, likely because of the contribution of abnormal luminal fluid content in CF. Acute management of DIOS involves the use of a variety of bowel-cleansing agents, depending on the degree of involvement. Intestinal lavage with a balanced electrolyte solution containing polyethylene glycol, use of oral N-acetylcysteine as a mucolytic agent, and high-dose diatrizoate meglumine and diatrizoate sodium (via both oral and rectal instillation) have been employed successfully. The particular cleansing protocol often varies with the institution. Chronic management should include optimizing fat absorption plus the use of cathartic agents and appropriate intake of fiber. Although DIOS is a relatively common gastrointestinal complication of CF, other problems must be considered in any patient who has CF and presents with gastrointestinal complaints. Some of the more prevalent, age-related problems are listed below. Presenting signs and symptoms of these disorders are similar to those in patients who do not have CF, and the clinician caring for patients who have CF must be aware of their occurrence in this patient group. A diagnosis of appendiceal abscess or Crohn disease is unlikely in this case because of the absence of associated symptoms of right lower quadrant abdominal pain, fever, or diarrhea. Functional constipation may exhibit one or more of the clinical findings described for this child, but the relatively recent onset in a child who has no history of stool withholding behavior, coupled with his malabsorptive state and increase in pancreatic enzyme requirement, points to DIOS as the most likely diagnosis, particularly considering its importance and frequency in patients who have CF. Fibrosing colonopathy is an uncommon complication of pancreatic enzyme supplementation. It is associated with pancreatic enzyme supplementation in excess of 24,000 lipase units/kg per day. The risk of fibrosing colonopathy was particularly high when pancreatic enzymes were provided in a high-strength microencapsulated form (\>20,000 lipase units per capsule), which no longer is marketed. Due to enzyme reformulation that reduced the lipase content per capsule and current recommendations limiting maximal lipase supplements to 10,000 enzyme units/kg per day, the incidence of fibrosing colonopathy has been reduced dramatically.

Question 52

You are caring for an 8-month-old infant in the pediatric intensive care unit. She has been hospitalized for 1 week with respiratory syncytial virus bronchiolitis. In discussions with the mother, she reports that the child has very frequent, large, foul-smelling stools. Physical examination of the child reveals a temperature of 37.0°C, heart rate of 140 beats/min, respiratory rate of 35 breaths/min on the ventilator, and blood pressure of 80/40 mm Hg. Her oxygen saturation is 90%, and her most recent arterial blood gas shows a pH of 7.25, PaCO2 of 70 mm Hg, and PaO2 of 70 mm Hg. Her weight is 7 kg, and she appears malnourished, with decreased muscle development. No obvious congenital abnormalities are apparent. Her chest appears hyperinflated, she has no heart murmur, her pulses are equal and strong, and her abdomen is protuberant with normal bowel sounds. Computed tomography scan of her chest was obtained earlier today to evaluate enlarging cystic-appearing lesions on her chest radiograph. Caption from the photo: CT scan of the chest showing cystic structures in the left lung (arrow). (Courtesy of B. Poss) Of the following, the MOST likely underlying diagnosis in addition to bronchiolitis is: * congenital lobar emphysema * cystic adenomatoid malformation * cystic fibrosis * pulmonary sequestration * Clostridium difficile infection

Answer 52

**Answer:** cystic fibrosis **Explanation:** The correct answer is Cystic Fibrosis because The child described in the vignette was admitted to the pediatric intensive care unit forbronchiolitis, but her history of failure to thrive and malabsorption as well as cystic lesions on radiologic imaging are consistent with cystic fibrosis. Cystic fibrosis can have a variety of presentations, including failure to thrive, delayed passage of stool, abnormal stools, rectal prolapse, and electrolyte abnormalities, but acute or chronic respiratory symptoms account for more than 50% of all presentations. Cough frequently is the first respiratory symptom, but progression to wheezing, shortness of breath, and recurrent pneumonia is common. Infants younger than 1 year of age can have bronchiolitis with wheezing, as described for the child in the vignette. Radiographic findings include hyperinflation, bronchial thickening, and patchy atelectasis. Progressive disease is evidenced by cyst formation, bronchiectasis, and lobar atelectasis. Severe complications of pulmonary disease that may be life-threatening can include development of pneumothoraces, cor pulmonale, and hemoptysis. Congenital disorders of the lung such as congenital cystic adenomatoid malformation, congenital lobar emphysema (Item C137), or pulmonary sequestration may present as respiratory distress during infancy, but they generally are not associated with malabsorption or failure to thrive. Clostridium difficile infection, which usually develops following antibiotic usage, can cause foul-smelling diarrhea, but failure to thrive is not a characteristic finding.

Question 53

You are called to the neonatal intensive care unit to examine a newborn who has abdominal distention and respiratory distress. She was born at 38 weeks’ gestation and weighs 4 kg. Apgar scores were 3 and 6 at 1 and 5 minutes, respectively. She required tracheal intubation and assisted ventilation. On physical examination, she has a large, distended, and tense abdomen without bowel sounds. The abdominal wall is not erythematous, and there is no clearly palpable mass. She does not display other evidence of body wall or scalp edema. The breath sounds are coarse and equal bilaterally. There is no heart murmur. Radiograph of the chest appears normal, but abdominal radiography shows background granular density, paucity of intraluminal bowel gas, and a calcified mass in the left lower quadrant (Item Q210). Of the following, the BEST explanation for this infant’s abdominal findings is * urinary ascites * ovarian cyst * erythroblastosis fetalis * congenital lymphangioma * meconium peritonitis

Answer 53

**Answer:** meconium peritonitis **Explanation:** The respiratory distress described for the infant in the vignette may be related to diaphragmatic impingement from abdominal distention. Evaluation of the cause of abdominal distention includes a plain radiograph that, in this case, has findings consistent with ascites and a calcified mass (see below). Subsequent abdominal ultrasonography may prove to be valuable diagnostically. The mass is a meconium pseudocyst, indicative of a bowel rupture with contained (walled-off) meconium that has become calcified. This condition, seen in meconium peritonitis, usually is associated with meconium ileus and is a result of cystic fibrosis (CF). An autosomal recessive disease, CF is believed to affect 1 in 2,000 to 4,000 live births of white children. It occurs much less frequently in African Americans (estimated at 1 in 17,000 live births) and is rare in infants of Asian descent (estimated at 1 in 90,000 live births). The disease is related to altered epithelial cell ion transport and is associated with exocrine pancreatic insufficiency and pulmonary decompensation in later life. More than 1,000 mutations (mapped to the 7th chromosome) have been identified, but the most common defect is in a chloride channel transmembrane transport protein regulated by the delta-F508 mutation, which accounts for more than 70% of all CF cases. Problems that may present in the neonatal period include: 1. Meconium ileus, a thick meconium obstruction of the distal ileum characteristically presenting clinically as a small bowel obstruction. This condition occurs in approximately 17% of infants who have CF. A history may indicate polyhydramnios, a prenatal ultrasonographically observed bowel dilation, or delayed postnatal passage of stool. Physical examination may reveal abdominal distention and bile-stained emesis. A plain abdominal radiograph may show stacked loops of variably dilated bowel, soap-suds bubbly-like appearance of meconium stool (most often in the right lower quadrant), and a ground-glass character of the distal bowel with a relative paucity of distal bowel gas. A contrast enema may reveal a microcolon and failure to pass contrast beyond the ileocecal valve. Surgical exploration and removal of inspissated meconium is generally necessary, as may be a temporizing ileostomy and later reanastamosis. 2. Meconium peritonitis is associated with bowel obstruction leading to perforation and spillage of meconium into the peritoneal cavity, occasionally involving a walled-off calcified meconium "pseudocyst" apparent on plain abdominal radiograph or abdominal ultrasonography. The perforation may have occurred in utero and may be associated with fetal ascites or hydrops, pulmonary hypoplasia and respiratory failure, and impaired bowel or liver function. The newborn may have ascites or anasarca on physical examination, with a tense, distended abdomen. Plain abdominal radiography may reveal a diffuse ground-glass density and little intraluminal bowel gas; there also may be diffuse or focal calcification (see below). Medical management is directed at stabilizing pulmonary function, fluid and electrolyte balance, and hepatic function before addressing the surgical condition. 3. Prolonged jaundice with a predominance of conjugated hyperbilirubinemia also is seen in infants who have CF and may result from inspissated bile or prolonged use of parenteral nutrition. Congenital lymphangiomas may present with ascites and hydrothoraces requiring drainage; analysis of the fluid confirms the diagnosis. Erythroblastosis fetalis is an isoimmune hemolytic condition that involves fetal hydrops (neonatal anasarca) and profound anemia, but it is not related to bowel obstruction and does not result in meconium peritonitis. Ovarian cysts may be massive, occasionally resulting in bowel compression and extrinsic obstruction that can require surgical excision. They are discernible by abdominal and pelvic ultrasonography as being distinct from the bowel lumen. Urinary ascites develops following urinary tract obstruction, with perforation and leakage of urine into the peritoneal space. It occurs most commonly in boys who have posterior urethral valves. Analysis of the ascites fluid reveals an elevated creatinine concentration. References: - Albanese CT, Sylvester KG. Pediatric surgery. In: Doherty GM, Way LW. Current Surgical Diagnosis and Treatment. 12th ed. New York, NY: The McGraw-Hill Companies, Inc; 2006:chap 45 - Copyright © 2009 by the American Academy of Pediatrics page 700 2009 PREP SA on CD-ROM - Chaudry G, Navarro OM, Levine DS, Oudjhane K. Abdominal manifestations of cystic fibrosis in children. Pediatr Radiol. 2006;36:233-240. Abstract available at: http: //www.ncbi.nlm.nih.gov./pubmed/16391928 - Davis PB. Cystic fibrosis. Pediatr Rev. 2001;22:257-264. Available at: http: //pedsinreview.aappublications.org/cgi/content/full/22/8/257 - Kaye CI and the Committee on Genetics. Newborn screening fact sheets. Pediatrics. 2006;118:e934-e963. Available at: http://pediatrics.aappublications.org/cgi/content/full/118/3/e934

Question 54

An elderly man and his teenage grandson are found dead in their mobile home. The scene is secure with no evidence of forced entry and none of the bodies show any sign of trauma. No windows are open and the trailer is heated with a kerosene heater. Which of the following mechanisms of death is most likely? * Asphyxia * Decreased hemoglobin synthesis * Pulmonary edema * Cardiac arrhythmia * Necrosis of the globus pallidus

Answer 54

**Answer:** Asphyxia **Explanation:** Carbon monoxide is asphyxia at the cellular level with CO interfering with the binding of oxygen to hemoglobin. Carbon monoxide exposure is not associated with pulmonary edema (other drug deaths, esp. barbituates and heroin), cardiac arrhythmias (Cocaine), or decreased hemoglobin synthesis (lead). If the patient survives CO poisoning, necrosis of the globus pallidus does occur but it is not associated with the acute death.

Question 55

Social services are doing an evaluation of a family in a socioeconomically depressed inner city. Of the five children, three are in public school and all are performing lower than their grade level. Two of the three have been evaluated in school for behavioral difficulties. A 4-year-old is in foster care, having been removed from the mother when she tested positive for cocaine at delivery. An 18-month-old male is noted to have mild dysmorphic facial features consisting of a short palpebral fissure, “railroad track” ears, and a smooth philtrum. His weight, height and head circumference are all below 25% for age, and he has developmental delays with very poor verbal skills. Which of the following is the most likely diagnosis for this child? * Lead exposure * Fragile X syndrome * Fetal alcohol syndrome * Down syndrome * In utero cocaine exposure (“Crack” baby)

Answer 55

**Answer:** Fetal alcohol syndrome **Explanation:** The physical findings are associated with fetal alcohol syndrome, which commonly affect multiple family members if there is not intervention. Cocaine exposure is associated with marked changes at birth but not long term affects. Lead could explain the developmental delays and behavioral issues but not the physical findings of the children, and it is unlikely that multiple children would be affected with Down syndrome or Fragile X.

Question 56

Which of the following antibiotics is not considered bactericidal? * Penicillin * Doxycycline * Vancomycin * Imipenem

Answer 56

**Answer:** Doxycycline **Explanation:** Doxycycline is a tetracycline that inhibits protein synthesis by binding with the 16s rRNA of the 30S ribosomal subunit of susceptible bacteria inhibiting peptide elongation and thereby protein formation. Penicillin and imipenem are β-lactam drugs that bind to penicillin-binding proteins, disrupting cell wall synthesis which results in a bactericidal effect (cell lysis). Vancomycin is a glycopeptide that inhibits bacterial cell wall synthesis by binding tightly to cell wall precursors resulting in cell lysis. Bactericidal antibiotics are generally preferred to treat serious infections such as endocarditis or bacterial meningitis.

Question 57

Negative health impacts from environmental exposures have been a concern of populations for thousands of years. Which statement is correct regarding these exposures and steps taken to mitigate the risk? * The London Smog of 1952 was primarily caused by automobile exhaust. The British government instituted fuel mileage standards to reduce these emissions. * Agricultural runoff is a major source of surface water pollution responsible for algal blooms (eutrophication). The Resource Conservation and Recovery Act (RCRA) limits these discharges. * In the early 20th century drinking water was responsible for thousands of typhoid cases each year in Philadelphia. Filtration and chlorination of water supplies dramatically reduced the typhoid incidence rate. * Regulated Medical Waste (RMW) began washing up on beaches in New Jersey and other states in the 1980s. Congress passed laws giving EPA federal oversight of all RMW management.

Answer 57

**Answer:** In the early 20th century drinking water was responsible for thousands of typhoid cases each year in Philadelphia. Filtration and chlorination of water supplies dramatically reduced the typhoid incidence rate. Chlorination and filtration of water supplies lowered the typhoid rate in Philadelphia and other major U.S. cities. * The London Smog of 1952 was primarily caused by automobile exhaust. The British government instituted fuel mileage standards to reduce these emissions. INCORRECT. The smog was caused mostly by coal fired heating and automobiles were not a major factor. * Agricultural runoff is a major source of surface water pollution responsible for algal blooms (eutrophication). The Resource Conservation and Recovery Act (RCRA) limits these discharges. INCORECT. The Clean Water Act regulates agricultural runoff and other surface water discharges. * Regulated Medical Waste (RMW) began washing up on beaches in New Jersey and other states in the 1980s. Congress passed laws giving EPA federal oversight of all RMW management. INCORRECT. Management of RMW is a function of left to the states (but DoD must comply).

Question 58

On a routine physical exam, a 65-year-old male indicates that he has spent several weeks sand-blasting away the internal paint in an old house he is remodeling. Which of the following would he be most likely to develop if he did have excessive lead exposure? * Confusion and mental deterioration * Radiodense lines on radiographs of long bones * Elevated carboxyhemoglobin saturation * Chloracne and skin hyperpigmentation * Abdominal pain

Answer 58

**Answer:** Abdominal pain **Explanation:** Confusion and mental deterioration are features of lead poisoning in children, not adults. Radiodense lines on radiographs of long bones are seen in lead poisoning of children, not adults. Elevated carboxyhemoglobin saturation is indicative of carbon monoxide exposure. Chloracne and skin hyperpigmentation are features of dioxin and PCB exposure. Abdominal pain and GI symptoms are typical of adult presentations of lead poisoning (See Robbins f. 9-6, p. 407).