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Question 1

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Answer 1

Patients undergoing cardiothoracic or orthopedic surgery should be screened for nasal carriage of Staphylococcus aureus and, if positive, should have preoperative decolonization.

Question 2

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Answer 2

Immune reconstitution inflammatory syndrome is the return of a robust immune response resulting from treatment of HIV that may “unmask” a pre-existing infection; when this occurs, the underlying infection should be treated while antiretroviral therapy is continued.

Question 3

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Answer 3

This endemic dimorphic fungal infection is known to mimic other diseases, including tuberculosis, histoplasmosis, sarcoidosis, and cancer. The patient is stationed in Bakersfield, California, an epicenter for this infection. In addition, his assignment as a car mechanic, with much of his work likely conducted outside, increases the risk of infection. Another clue is his peripheral eosinophilia. A definitive diagnosis generally is made on the basis of serology and histopathologic analysis of tissue. When coccidioidomycosis is diagnosed, first-line therapy is fluconazole to prevent progressive or disseminated disease

Question 4

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Answer 4

Guideline-based recommendations for empiric therapy of community-acquired pneumonia requiring ICU admission include a β-lactam (ampicillin-sulbactam, cefotaxime, ceftriaxone, or ceftaroline) to treat Streptococcus pneumoniae, gram-negative bacilli, or Haemophilus influenzae plus an agent active against Legionella, such as a macrolide or quinolone.

Question 5

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Answer 5

Initial studies for fever of unknown origin in most patients typically include a complete blood count with differential, complete metabolic profile with kidney and liver studies, at least three blood culture sets and cultures of other bodily fluids (such as urine or from other sources based on clinical suspicion), an erythrocyte sedimentation rate, tuberculosis testing, and serology for HIV; it is reasonable to perform chest imaging (radiography or CT) as initial diagnostic imaging.

Question 6

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Answer 6

Leptospiral meningitis usually develops weeks after exposure, during the second phase of illness, and can present with uveitis, rash, conjunctival suffusion, sepsis, lymphadenopathy, kidney injury, and hepatosplenomegaly.

The cerebrospinal fluid (CSF) findings resemble enteroviral meningitis, but empiric treatment with doxycycline should be started pending confirmation.

Question 7

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Answer 7

Fulminant Clostridium difficile infections require oral vancomycin plus intravenous metronidazole; vancomycin enemas may also be added if ileus is present.

Oral vancomycin alone for 10 days is recommended for treatment of an initial episode of nonsevere and severe CDI. Oral fidaxomicin can also be used.

Question 8

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Answer 8

Post–Lyme disease syndrome is a poorly understood sequela of Lyme disease thought to be due to a disordered immunologic response to the preceding infection; most patients slowly improve over a 6-month course, and treatment is directed toward symptom amelioration.

Question 9

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Answer 9

Rapidly growing, nontuberculous mycobacteria, such as Mycobacterium fortuitum, can produce chronic, nonhealing wounds that do not respond to conventional antimicrobial therapy.

Leprosy is caused by the acid-fast bacillus Mycobacterium leprae, a slow-growing organism. Leprosy should be considered in the setting of chronic skin lesions that fail to respond to treatment of common skin conditions or when sensory loss is observed within lesions or in extremities.

Question 10

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Answer 10

In patients with a high likelihood of pelvic inflammatory disease without indications for hospitalization, empiric therapy with intramuscular ceftriaxone and oral doxycycline is appropriate without waiting for microbiologic testing results.

Question 11

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Answer 11

Screening for and possibly treating asymptomatic bacteriuria is supported by only two indications: pregnancy and medical clearance before an invasive urologic procedure.

Question 12

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Answer 12

This patient has sustained a possible exposure to HIV and should begin postexposure prophylaxis as soon as possible with a three-drug regimen of tenofovir, emtricitabine, and dolutegravir.

Preferred HIV postexposure prophylaxis regimens include tenofovir disoproxil fumarate, emtricitabine, and either dolutegravir or raltegravir and are appropriate whether the exposure was occupational or nonoccupational.

Question 13

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Answer 13

Acute, uncomplicated pyelonephritis can usually be managed with oral outpatient antimicrobial therapy, with the fluoroquinolones ciprofloxacin and levofloxacin being the preferred, first-line agents.

Question 14

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Answer 14

Patients with selective IgA deficiency are susceptible to Giardia lamblia infection, manifesting as abdominal cramping, bloating, and chronic diarrhea.

Question 15

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Answer 15

In patients with potential Zika virus exposure more than 2 weeks previously, testing for Zika virus IgM antibodies is necessary.

Question 16

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Answer 16

Varicella-zoster virus is a cause of Ramsay Hunt syndrome, which usually presents with ear pain, a vesicular rash in the external ear (although the rash may be absent), and ipsilateral peripheral facial palsy.

Question 17

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Answer 17

Coxiella- LIVESTOCK

Yersinia pestis infection of the lung causes pneumonic plague. Rodents serve as the primary reservoir for plague

Pneumonic tularemia occurs either after direct inhalation or through secondary spread of Francisella tularensis into the lungs. RABBITS

Chlamydia psittaci is the causative agent of psittacosis, which typically presents as pneumonia associated with abrupt onset of fever, severe headache, and dry cough. BIRD DROPPINGS

Question 18

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Answer 18

Coagulase-negative Staphylococcus is less virulent than S. aureus and is less likely to cause metastatic infection or endocarditis in patients without prosthetic devices or endovascular hardware in place (such as prosthetic heart valves) and may be treated with simple removal of the intravenous catheter.

Coagulase-negative Staphylococcus CLABSIs often resolve with removal of the catheter. Blood cultures should be repeated after catheter removal to document clearance of the organism. Alternatively, patients with coagulase-negative Staphylococcus CLABSIs can be treated with antibiotics for 5 to 7 days if the catheter is removed and for 10 to 14 days in combination with antibiotic lock therapy if the catheter is not removed.

Question 19

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Answer 19

Early removal of urinary catheters should be considered when possible, and patients should be monitored for their ability to void spontaneously after catheter removal.

Question 20

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Answer 20

Human monocytic ehrlichiosis infection is characterized by a nonfocal febrile illness associated with leukopenia, thrombocytopenia, elevated hepatic enzyme levels, and a rapid response to tetracycline.

HME is endemic in the mid-Atlantic, southern, and southeastern United States;

Question 21

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Answer 21

In patients with health care–associated ventriculitis or meningitis, device removal, if present, should accompany empiric antimicrobial therapy.

Staphylococcus species and enteric gram-negative bacteria are the most common causes, but up to 50% of patients can have negative cultures because more than 50% receive antibiotic therapy before CSF studies are performed, as occurred in this patient.

Question 22

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Answer 22

First-line treatment for primary pneumonic plague is either streptomycin or gentamicin.

This patient most likely has pneumonic plague caused by the bacteria Yersinia pestis, one of the biologic agents classified as an A-list bioterrorism pathogen because of its high potential lethality and ease of dissemination. Sputum Gram stain (and possibly blood smear) may identify gram-negative coccobacilli demonstrating the classic bipolar staining or “safety pin” shape shown

Question 23

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Answer 23

Liposomal amphotericin B is the treatment of choice for disseminated histoplasmosis.

Approximately 10% of patients with histoplasmosis develop disseminated infection; if not diagnosed early, the mortality rate is greater than 90%. The treatment of choice for disseminated histoplasmosis is liposomal amphotericin B initially, with de-escalation to itraconazole for several months

Question 24

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Answer 24

In patients with pneumonia unresponsive to appropriate antibiotic therapy, a noninfectious cause mimicking pneumonia, antibiotic-resistant bacterial infection, infection with a nonbacterial organism, or loculated infection such as an empyema may be the cause.

Antibiotic therapy failure may indicate a noninfectious cause mimicking pneumonia, antibiotic-resistant bacterial infection, infection with a nonbacterial organism, or loculated infection such as an empyema.

Question 25

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Answer 25

Daptomycin is contraindicated for use in pulmonary infections because it binds to surfactant and does not achieve adequate levels in the alveoli.

Question 26

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Answer 26

Plasmodium falciparum infection should be suspected if the patient traveled to Africa, symptoms begin soon after return from an endemic area, and the peripheral blood smear shows a high level of parasitemia.

Question 27

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Question 28

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Answer 28

Patients with spinal epidural abscess who also have neurologic compromise should immediately begin broad-spectrum antimicrobial therapy and undergo surgical drainage.

Question 29

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Answer 29

Fever is the major manifestation of typhoid fever and is often associated with a relative bradycardia; additional symptoms may include a brief period of diarrhea followed by constipation, abdominal discomfort, nonproductive cough, mild confusion, and transient small blanching skin lesions (rose spots). Human brucellosis can develop after exposure to one of four Brucella species through contact with viable organisms in secretions or excretions of infected animals, ingestion of undercooked meat or milk products, or, less often, inhalation Humans acquire leptospirosis after contact with infected urine spread by carrier animals. Classically, illness is biphas

Question 30

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Answer 30

Genotypic viral resistance testing is recommended immediately after a diagnosis of HIV infection to guide the selection of active agents for the antiretroviral regimen or after virologic failure of a regimen to guide adjustment of antiretroviral therapy.

Question 31

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Answer 31

Herpes simplex virus type 2 can cause acute aseptic meningitis year round and is the most common cause of recurrent viral meningitis. HSV-2 is more commonly associated with meningitis and is the most common cause of recurrent meningitis (recurrent benign lymphocytic meningitis). HSV-1 is associated with encephalitis. HSV can cause meningitis year round. CSF findings resemble enteroviral meningitis, with lymphocytic pleocytosis, a normal glucose level, and a mildly elevated protein level as in this patien

Question 32

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Answer 32

In a patient with Lyme disease and possible central nervous system involvement, positive findings on lumbar puncture can support the diagnosis of neuroborreliosis, which necessitates parenteral therapy with ceftriaxone, cefotaxime, or penicillin.

Question 33

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Answer 33

Patients with no known direct exposure to anthrax do not require treatment or separation from those who may be infected. In cases of proven or suspected anthrax in a family member, no specific treatment or isolation procedures are required for others in the household because spread in health care or household settings has never been demonstrated In patients with confirmed or suspected bioterrorism-related anthrax exposure, postexposure prophylactic antibiotics, taken for 60 days, should be started as soon as possible. Ciprofloxacin, levofloxacin, and doxycycline are the approved drugs

Question 34

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Answer 34

he most appropriate preventive measure for this patient is daily tenofovir disoproxil fumarate and emtricitabine (TDF-FTC). He has multiple risk factors for acquiring HIV infection, including having sex with multiple partners without consistent condom use. Data support the use of pre-exposure prophylaxis (PrEP) in specific populations with ongoing high risk for infection, such as sexual partners of infected persons, men who have sex with men, and injection drug users.

Question 35

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Answer 35

Osteomyelitis in a patient with a diabetic foot infection and no evidence of skin or soft tissue infection or sepsis requires a bone biopsy before antibiotics are administered. Confirming a microbiologic diagnosis is needed before antibiotics can be administered. Indications for amputation include persistent sepsis, inability to tolerate antibiotic therapy, progressive bone destruction despite therapy, and bone destruction that compromises the mechanical integrity of the foo

Question 36

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Answer 36

In patients with previously treated syphilis, treponemal serology results will remain positive, but nontreponemal tests will be negative; these patients require no further testing or treatment. A positive EIA (confirmed by a second test) with a negative RPR is the expected serologic result in a patient who has been treated for syphilis. The treponemal test (EIA) remains positive indefinitely, but the nontreponemal test (RPR or VDRL) should remain negative. \

Question 37

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Answer 37

A screening HIV test result that is positive on the initial antigen/antibody combination immunoassay but negative on the antibody differentiation immunoassay and nucleic acid amplification testing for HIV RNA represents a false-positive result. If reactive, an HIV-1/2 antibody differentiation immunoassay is performed, which differentiates between HIV-1 and HIV-2 antibodies. If the antibody differentiation assay is reactive for HIV-1 antibody, then HIV-1 infection is confirmed. If the antibody differentiation assay is negative, then testing for HIV RNA by nucleic acid amplification is performed. A negative antibody differentiation assay with a positive HIV RNA test would indicate acute HIV infection (in the “window” period after infection but before antibody development).

Question 38

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Answer 38

The protozoan Cryptosporidium is the most common cause of swimming pool–related outbreaks of diarrhea; diagnosis is made by microscopic examination of the stool or by stool antigen testing. Norovirus is the most common cause of gastroenteritis and is characterized by explosive vomiting and diarrhea. It is spread person to person through the fecal-oral route, leading to community outbreaks Vibrio parahaemolyticus lives in salt water and causes diarrhea, usually after consumption of undercooked shellfish, especially oysters.

Question 39

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Answer 39

Persons with chronic inflammatory bowel disease or who are immunocompromised are most susceptible to severe travelers' diarrhea or complications, and prophylaxis (fluoroquinolones preferred) should be provided to these patients.

Question 40

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Answer 40

Central venous catheters should be assessed daily for continued necessity and removed promptly when they are no longer needed.

Question 41

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Answer 41

Cyclospora infection is treated with oral trimethoprim-sulfamethoxazole. Cyclospora protozoan infections are typically acquired after consumption of fecal-contaminated food or water, particularly in countries where the parasite is endemic, such as Peru, Guatemala, Haiti, and Nepal.

Question 42

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Answer 42

Antiretroviral therapy during pregnancy is crucial and significantly decreases the risk of perinatal transmission of HIV to the baby. A woman whose HIV is well controlled and is found to be pregnant should continue the same regimen unless another reason exists to change it.

Question 43

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Answer 43

Hepatitis A vaccination should ideally occur 2 to 4 weeks before travel to an endemic region; however, a single dose of the vaccine given any time before travel provides adequate protection to otherwise healthy persons.

Question 44

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Answer 44

The carbapenem class of antibiotics (imipenem, meropenem, doripenem, ertapenem) is the preferred class of agents for treating infections with extended-spectrum β-lactamase–producing organisms.

Question 45

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Answer 45

Patients receiving daptomycin therapy should undergo baseline measurement of kidney function and creatine kinase level followed by weekly monitoring. However, daptomycin is known to cause elevated levels of CK and can contribute to the development of myopathy during therapy. Daptomycin should be discontinued in asymptomatic patients if CK levels increase to greater than 10 times the upper limit of normal or the CK level is greater than 5 times the upper limit of normal with symptoms of myopathy. Concomitant treatment with statins (particularly simvastatin and atorvastatin) may increase the chance of developing an elevated CK level; it is suggested that statins be discontinued if possible during daptomycin treatment.

Question 46

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Answer 46

Kaposi sarcoma can develop in patients with AIDS infected with human herpes virus type 8, presenting with painless violaceous skin nodules with oral involvement. Human herpes virus type 6 causes roseola infantum, febrile seizures in children, and cytomegalovirus-seronegative and EBV-seronegative mononucleosis. It does not cause skin nodules.

Question 47

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Answer 47

Rifampin should be used in combination with another antistaphylococcal agent when managing Staphylococcus aureus osteomyelitis in the setting of orthopedic hardware if the hardware cannot be removed. Optimal management of this patient's infection includes hardware removal; however, this is not possible because the fracture has not yet healed. Hardware-associated infections caused by S. aureus are difficult to eradicate because of the biofilm that forms on the hardware. First-line treatment of MSSA osteomyelitis consists of a β-lactam agent such as cefazolin; a randomized controlled trial and systematic review of the literature have demonstrated that if infected hardware cannot be removed, the addition of rifampin increases the chances of therapeutic success compared with an antistaphylococcal agent alone.

Question 48

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Answer 48

Amoxicillin-clavulanate is recommended for patients with animal bites who are immunosuppressed (including patients with cirrhosis and asplenia); have wounds with associated edema, lymphatic or venous insufficiency, or crush injury; have wounds involving a joint or bone; have deep puncture wounds; or have moderate to severe injuries, especially when involving the face, genitalia, or hand.

Question 49

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Answer 49

Ceftolozane-tazobactam is a newer antipseudomonal cephalosporin combined with a β-lactamase inhibitor that can be used in the treatment of multidrug-resistant intra-abdominal infection.

Question 50

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Answer 50

The microbiology of community-acquired pneumonia in pregnancy is similar to that seen in the general population; among patients requiring hospitalization, the most common pathogens are Streptococcus pneumoniae, Haemophilus influenzae, and atypical organisms, including Legionella species, Chlamydia pneumoniae, and Mycoplasma pneumoniae.

Question 51

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Answer 51

On testing for HIV infection, a positive result on HIV-1/2 antigen/antibody combination immunoassay is followed by testing with the HIV-1/HIV-2 antibody differentiation immunoassay; a negative antibody differentiation immunoassay but a positive follow-up HIV-1 nucleic acid amplification test is diagnostic of acute HIV infection.

Question 52

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Answer 52

His initial HIV-1/2 antigen/antibody combination immunoassay is reactive, indicating further testing is needed. The HIV-1/HIV-2 antibody differentiation assay is negative, indicating the absence of antibody to HIV; however, the RNA assay is positive for HIV-1 RNA. This finding indicates the patient does not have antibodies to HIV but does demonstrate the presence of virus by nucleic acid amplification testing

Question 53

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Answer 53

Patients who undergo allogeneic hematopoietic stem cell transplantation (HSCT) usually experience a period of prolonged neutropenia after the pretransplant myeloablative conditioning regimen. This prolonged, severe neutropenia is a significant risk factor for invasive bacterial and fungal infections, and prophylaxis for both is indicated.

Question 54

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Answer 54

Tuberculosis and cryptococcus are the most common causes of chronic meningitis; empiric treatment for tuberculous meningitis includes four-drug antituberculous therapy (rifampin, isoniazid, pyrazinamide, and ethambutol) plus dexamethasone.

Question 55

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Answer 55

Prophylactic treatment with isoniazid is a recommended alternative treatment option for persons with latent tuberculosis infection, determined by a newly positive tuberculosis screening test but no signs or symptoms of active disease; 9 months of daily isoniazid can be self-administered. Because the chest radiograph is negative, he requires treatment for latent tuberculosis rather than treatment with the four-drug regimen for active tuberculosis.

Question 56

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Answer 56

The first month after solid organ transplantation is when the most likely infections are nosocomial and similar to those in patients who have had other surgeries; patients who have recently completed antimicrobial treatment are particularly at increased risk for Clostridium difficile colitis.

Question 57

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Answer 57

Babesiosis can be diagnosed by visualization of intraerythrocytic parasites in a ring or tetrad form on a blood smear.

Question 58

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Answer 58

A positive blood culture for Candida species should not be treated as a contaminant, and empiric therapy with an echinocandin should be instituted immediately. Fluconazole is not recommended as initial management for this patient. Several Candida species, such as C. glabrata, C. auris, and C. krusei, are known to be intrinsically resistant to azoles.

Question 59

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Answer 59

The recommended duration of antibacterial therapy for acute vertebral osteomyelitis is 6 weeks.

Question 60

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Answer 60

When treating methicillin-resistant Staphylococcus aureus bacteremia, vancomycin should be used only if the minimum inhibitory concentration is 2 µg/mL or less.

Question 61

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Answer 61

In patients with community-acquired pneumonia and risk factors for Pseudomonas aeruginosa infection, the use of dual therapy with antipseudomonal, antipneumococcal β-lactam, or an antipseudomonal carbapenem, and antipseudomonal quinolone agents is recommended for initial empiric therapy.

Question 62

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Answer 62

Patients with common variable immunodeficiency are at increased risk of recurrent respiratory tract infections with encapsulated organisms (Streptococcus pneumoniae, Haemophilus influenzae), and they may develop chronic diarrhea because of enteroviruses, norovirus, or Giardia.

Question 63

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Answer 63

Mycobacterium marinum is found worldwide in freshwater and saltwater aquatic environments, typically causing indolent skin or soft tissue infection and usually appearing as papules on extremities after contact and trauma from fish tanks, fish, or shellfish.

Question 64

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Answer 64

Patients with HIV who are taking antiretroviral therapy and achieve CD4 cell counts greater than 200/µL for more than 3 months may safely discontinue prophylaxis for Pneumocystis jirovecii infection. Atovaquone would be an acceptable alternative to trimethoprim-sulfamethoxazole for prophylaxis of Pneumocystis, but this patient no longer requires Pneumocystis prophylaxis with any agent.

Question 65

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Answer 65

Ventilator-associated pneumonia should be treated with a 7-day course of antibiotics; longer courses contribute to the emergence of antibiotic resistance, increase the risk for antibiotic-related adverse effects, and do not improve outcomes.

Question 66

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Answer 66

When other causes of encephalitis have been ruled out in a patient presenting with associated changes in mood and behavior, anti-N-methyl-D-aspartate receptor encephalitis should be suspected.

Question 67

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Answer 67

The microbiologic diagnosis of tuberculosis should be verified by acid-fast bacilli staining of sputum samples and nucleic acid amplification testing before initiating antituberculous therapy. Although it is essential to initiate antimicrobial therapy promptly, it is important to verify the microbiologic diagnosis of Mycobacterium tuberculosis infection first by submitting three sputum specimens for AFB staining and culture.

Question 68

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Answer 68

Nontyphoidal Salmonella is commonly carried asymptomatically by reptiles and amphibians and transferred from the animals' feces to people; human symptoms include crampy abdominal pain, fever, nonbloody diarrhea, and vomiting.

Question 69

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Answer 69

Staphylococcus aureus bacteremia persisting more than 72 hours after the start of appropriate antimicrobial therapy suggests a complicated infection requiring additional evaluation; endocarditis, osteomyelitis, and intra-abdominal infections are important sites of metastatic infection.

Question 70

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Answer 70

Lacerations and puncture wounds sustained in fresh and brackish water environments can result in necrotizing infection with Aeromonas hydrophila; this infection should be treated with surgery, supportive care, and antibiotics with gram-negative coverage, such as doxycycline plus ciprofloxacin.

Question 71

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Answer 71

In patients at high risk, doxycycline prophylaxis has been shown to decrease the risk of Lyme disease if started within 72 hours of tick removal, assuming that the tick has been attached for at least 36 hours. Checking B. burgdorferi titers similarly has low yield because antibodies may not be present during the early stages of infection, and paired serologic testing with a subsequent convalescent specimen in the absence of symptoms is not cost effective.

Question 72

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Answer 72

Vaccinia immunization is appropriate in the event of possible exposure to smallpox (variola).

Question 73

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Answer 73

Infection with varicella-zoster virus in a young patient should prompt testing for HIV infection. Older adults and immunocompromised patients, including patients with HIV infection, are at increased risk. Severe or recurrent varicella-zoster virus infections or infection at a young age should prompt an evaluation for HIV infection.

Question 74

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Answer 74

Sporadic Creutzfeldt-Jakob disease is the most common form of prion disease, involving several neurologic systems and rapid progression of apparent dementia. On physical examination, ataxia, myoclonus, and a rapidly progressive dementia are present. MRI abnormalities are not specific for sCJD and vary with the clinical syndrome. Patients with increased T2 signal in the caudate and putamen are more likely to have early dementia and shorter survival.

Question 75

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Answer 75

Primary enterohemorrhagic Escherichia coli infections should receive supportive care; administration of antibiotics or antimotility medications is associated with increased risk for hemolytic uremic syndrome.

Question 76

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Answer 76

Latent cytomegalovirus infection is present in 60% to 90% of adults, and patients who are immunosuppressed may experience disease reactivation with retinitis, pneumonitis, hepatitis, bone marrow suppression, colitis with bloody diarrhea, esophagitis, or adrenalitis.

Question 77

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Answer 77

A superficial incisional infection involves the underlying soft tissue and presents with inflammatory changes at the incision site (erythema, tenderness), with or without purulent drainage, and few if any systemic signs of infection such as fever; therapy is guided by Gram stain and culture of the wound.

Question 78

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Answer 78

Combination therapy with liposomal amphotericin B and flucytosine is the treatment of choice for cryptococcal meningitis. Fluconazole, an azole antifungal agent, has in vitro and in vivo activity against C. neoformans, but it is recommended as de-escalation therapy after the patient has received at least 2 weeks of amphotericin B and flucytosine and is clinically stable.

Question 79

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Answer 79

Fluoroquinolone antibiotics such as ciprofloxacin are associated with the development of tendinitis and tendon rupture, so patients should be counseled to report tendon or joint pain and swelling.

Question 80

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Answer 80

The preferred treatment for oropharyngeal candidiasis, including esophageal disease, is oral fluconazole, although esophageal involvement warrants a more prolonged treatment course. Topical agents such as nystatin are less effective than systemic fluconazole for oropharyngeal candidiasis and are especially ineffective for esophageal disease. If presumptive treatment for candida esophagitis is ineffective in improving symptoms, then upper endoscopy is indicated to better define the cause.

Question 81

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Answer 81

In patients with invasive candidiasis, therapy with an oral azole (if the Candida species is susceptible) or amphotericin B should be initiated immediately; the total duration of therapy should be 10 to 14 days.

Question 82

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Answer 82

Nucleic acid amplification testing is the most appropriate diagnostic choice for confirming genital ulcer disease caused by herpes simplex virus. HSV-1 is less able to establish latency in the genital region, so most recurrent genital infections are caused by HSV-2. NAAT is highly sensitive and specific for HSV. Regardless of type, the initial treatment of primary genital HSV infection is the same (acyclovir, valacyclovir, or famciclovir)

Question 83

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Answer 83

In patients with necrotizing fasciitis caused by group A Streptococcus, the combination of penicillin and clindamycin is indicated for antimicrobial therapy after surgical debridement.

Question 84

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Answer 84

No treatment is indicated for asymptomatic bacteriuria in otherwise healthy, nonpregnant patients.

Question 85

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Answer 85

Mediterranean spotted fever characteristically presents with fever, myalgia, and headache followed shortly by the appearance of a maculopapular and oftentimes petechial rash; a distinct black eschar is also classically present at the site of inoculation.

Question 86

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Answer 86

For patients presenting with aseptic meningitis and cerebrospinal fluid findings typical for viral infection, the “rule of 7s” can classify a patient at low risk for having Lyme disease (headache duration <7 days, <70% mononuclear cells, and absence of a seventh facial nerve palsy). Aseptic meningitis caused by herpes simplex virus type 2, West Nile virus, or enterovirus would include a normal neurologic examination. The presence of right-sided facial palsy in this patient makes these unlikely causes.

Question 86

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Answer 86

For patients presenting with aseptic meningitis and cerebrospinal fluid findings typical for viral infection, the “rule of 7s” can classify a patient at low risk for having Lyme disease (headache duration <7 days, <70% mononuclear cells, and absence of a seventh facial nerve palsy). Aseptic meningitis caused by herpes simplex virus type 2, West Nile virus, or enterovirus would include a normal neurologic examination. The presence of right-sided facial palsy in this patient makes these unlikely causes.

Question 87

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Answer 87

Posttransplant lymphoproliferative disorder caused by Epstein-Barr virus can present several years after transplantation with fever, pancytopenia, generalized lymphadenopathy, and hepatosplenomegaly. However, cytomegalovirus does not cause generalized lymphadenopathy or hepatosplenomegaly.

Question 88

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Answer 88

Purulent skin infections with systemic signs of infection should be managed with incision and drainage followed by empiric oral therapy with trimethoprim-sulfamethoxazole or doxycycline.

Question 89

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Answer 89

The criteria for a positive tuberculin skin test reaction have been established by the Centers for Disease Control and Prevention based on the patient's risks for tuberculosis; in patients with no risk factors for tuberculosis, 15 mm or greater should be considered a positive result.

Question 90

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Answer 90

A 5-mm induration on tuberculin skin testing is considered positive in persons who are immunocompromised, including those with HIV; if no other signs of tuberculosis infection are present, treatment for latent tuberculosis infection should be initiated with isoniazid. ecause the chest radiograph was negative, he should be treated as having latent tuberculosis infection (LTBI) with 9 months of isoniazid therapy

Question 91

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Answer 91

Ciprofloxacin and levofloxacin are the preferred antimicrobial agents for the treatment of recurrent cystis when trimethoprim-sulfamethoxazole local resistance rates are high or the patient has been treated with an antibiotic for a urinary tract infection within the previous 3 months.

Question 92

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Answer 92

Ciprofloxacin and levofloxacin are the preferred antimicrobial agents for the treatment of recurrent cystis when trimethoprim-sulfamethoxazole local resistance rates are high or the patient has been treated with an antibiotic for a urinary tract infection within the previous 3 months.