Gram negative Bugs

Question 1

Define the

• Lactose fermenting enteric bacteria
• what do they grow on
• produce what (and what does this thing do)
• how do they look on EMB agar?

Answer 1

• Citrobacter, Klebsiella, E. coli, Enterobacter, Serratia (weak fermenter).
• grow on MacConkey agar (pink)
• produce Beta-galactosidase: breaks down lactose into glucose and galactose
• EMB agar: grow as purple/blk (E.coli grows purple with green sheen)

Question 2

Penicillin and gram neg bugs

• resistance/susceptiblitiy
• G- moa w/penicillin and vancomycin

Answer 2

• resistant to penicillin G: susceptible (may be) to penicillin derivatives (ampicillin and amoxicillin)
• G- outer membrane layer inhibits entry of penicillin G and vancomycin

Question 3

Define a

G- diploccoci, both ferment glucose and produce IgA proteases.

Difference b/t the two

Answer 3

• Neisseria
• Meningoccoci (ferments maltose and glucose) & Gonococci (ferments glucose)
  
  • N. gonorrhoeae is often intracellular (w/in neutrophils)

Question 4

Gonococci vs Meningococci

• capsule
• maltose fermation
• vaccine
• transmission
• causes what
• prevention
• treatment

Answer 4

Gonococci

• No polysacchride capsule
• non maltose fermation
• no vaccine
• Sexually transmitted
• Causes: gonorrhea, septic arthritis, neonatal conjuntivitis, pelvic inflammtory disease (PID), Fitz-Hugh-Curtis syndrome
• Prevention:
  
  • condoms, prevent sexual transmission.
  • erythromycin oitment prvents neonatla transmission
• Treatment:
  
  • Ceftriaxone + (axithromycin or doxycycline) for possible chlamydia coninfection

Meningococci

• Polysaccharide capsule
• Maltose formation
• Vaccine is present (except type B)
• Respirtory and oral secretions
• Causes: meningococcemia, meningitis, waterhouse-friderichsen syndrome
• Prevention: Rifampin, ciprofloxacin or ceftriazone prophylaxis in close contacts
• Treatment: Ceftriaxone or penicillin G

Question 5

G - rod, stains poorly, used silver stain. Grow on charcoal yeast extract culture with iron and cysteine. Detected clinically by presence of antigen in urine. Aerosol transmission from environemntal water souce, habitat (e.g. air conditioning systems, hot water tanks). No person to person transmission.

• ID the organism
• Treatment
• additional key lab finding

Answer 5

• Legionella pneumophila
• **Legionnaires’ disease: **severe pneuomia, fever, GI and CNS symptoms
• Pontaic fever: mild flu like symptoms
• Labs show hyponatremia

Question 6

Pt presentation:

Sm gram neg (coccobacillary rod), aerosol transmission. Most invasive disease cause by capsule type B. Non typeable strains cause mucosal infections (otitis media, conjunctivitis, bronchoitis). Produce IgA protease. Culture on chocolate agar requires, factos V (NAD+) and factor X (hematin) for growth. can also be grown with S. aureus, which provides factor V.

Causes: Epiglottitis (cherry red in children) meningitis, ortitis media and pneumona (E-MOP).

• Id the organism
• Prevention
• Treatment

Answer 6

• Haemophilus influenzae
• Prevention:
  
  • Vaccine contains type B capsular polysaccharide (polyribosylribitol phosphate) conjugated to diphtheria toxoid or other protein.
  • Given 2-18 mo of age
  • does not cause flu!
• Treatment
  
  • **Mucosal infection: **amoxicillin +/- clavulanate
  • Meningitis: ceftriaxone, (Rifampin prophylaxis in close contacts)

Question 7

Aerobic gram - rod, non lactose fermenting, oxidase +, produces pyocyanin (blue green pigment), has a grape like odor. Water source. Produces endotoxin (fever shock, and exotoxin A (inactivates EF-2).

Assocaited w/: wound and burn infections, pneumonia (especially in cystic fibrosis) sepsis, external otitis (swimmer’s ears), UTI, Drug use and Diabetic osteomyelitis, hot tub folliculitis. Malignant otitis externia in diabetics.

• Define organism
• Define Ecthyma gangrenosum
• treatment
• Assoc with CF pt

Answer 7

• Pseudomonas aeruginosa
• Ecthyma gangrenosum: rapidly progressive, necrotic cutaneous lesions, caused by Pseudomanas bacterium. Typically seen in immunocompromised pts.
• Treatment:
  
  • aminoglycoside + extended- spectrum penicillin (piperacillin, ticarcillin, cefepime, imipenem, meropenem).
• Chronic pneumonia in CF pt is associated with biofilm.

Question 8

Define the 3 virulence factors of E. Coli

Answer 8

• Fimbriae: cystitis ad pyelonephritis
• K capsule: pneumonia, neonatal meningitis
• LPS endotoxin: septic shock

Question 9

No toxin produced, Adheres to apical surface, flattens villi, prevents absorption.

• Define strain and presentation

Answer 9

• EPEC
• Diarrhea usually in children (Pediatrics)

Question 10

Microbe invades intestinal mucosa and causes necrosis and inflammation. Clinical manifestations similiar to Shigella.

• Define strain & presentation

Answer 10

• EIEC
• Invasive, dysentery

Question 11

Produces heat labile and heat stable enteotoxins. No inflammation or invasion.

• Define strain and presentation

Answer 11

• ETEC
• traveler’s diarrhea (watery!!!!)

Question 12

Salmonella vs Shigella

• flagella
• transmission
• reservoirs animals or humans
• production of hydrogen sulfide
• Antibiotics on fecal excretion
• invades inteatinal mucosa and causes what?
• bloody diarrhea
• lactose fermentation

Answer 12

Salmonella

• flagella present (think salmon swim)
• Transmission: disseminate hematogenously
• reserevoirs animals
• produces Hydrogen sulfid
• antibiotics prolong fecal excretion of organism
• monocytic response
• causes bloody diarrhea
• does not ferment lactose

Shigella

• No flagella
• cell to cell transmission, no hematogenous spread
• reservoir humans and primates
• DOES not produce hydrogen sulfid
• antibiotics shorten fecal excretion
• invades intestinal mucosa and causes PMN infiltration
• Often causes bloody diarrhea
• Does not ferment lactose

Question 13

O157:H7 is the most common serotype. Produces shiga-like toxin that causes Hemolytic-uremic syndrome (triad of anemia, thrombocytopenia, and acute renal failure).

Microthrombi form an endothelium damaged by toxin–> mechanical hemolysis (schitocytes formed) and dec renal blood flow; microthrombi consume platelets–> thrombocytopenia.

• Define strain and presentation

Answer 13

• EHEC
• Presentation
  
  • Dysentery (toxin alone causes necrosis and inflammation)
  • Does not ferement sorbitol (distinguishes it from other E. coli

Question 14

an intestinal flora tha cause lobar pneumonia in alcoholics and diabetics when aspirated. Very mucoid colonies caused by abundant polysaccharide capsules. Red ‘current jelly’ sputum.

Also cause of nosocomial UTIs

• Define organism and presentation of 4 A’s

Answer 14

• Klebsiella
• Presentation
  
  • aspiration pneumonia
  • Abscess in lungs and liver
  • Alcoholics
  • di-A-betics

Question 15

found only in humans, characterized by rose spots on the abdomen, fever, headache, diarrhea. Can remain in gallbladder and cause a carrier state.

Answer 15

Salmonella typhi

Question 16

Many cause of bloody diarrhea, especially in children. fecal oral transmission through foods such as poultry meat, unpasteurized milk. comma or s-shaped oxidase + grows at 42oC .

• Define organism
• Common antecedent to what 2 diseases

Answer 16

• Campylobacter jejuni
• GBS (guillain-Barre syndrome) and reactive arthritis

Question 17

Produces profuse rice water diarrhea via enterotoxin that permanently activates Gs, increase cAMP. comma shaped, oxidase +, grows in alkaline media. Endemic to developing countries.

• Define the organism
• What is the treatment

Answer 17

• vibrio cholera
• prompt oral rehydration

Question 18

Usually transmitted from pet feces (puppies) contaminated milk or pork.

.

• define the organism
• Causes mesenteic adenitis that can mimic what 2 conditions?

Answer 18

• Yersinia enterocolitica
• Crohn disease or appendicitis

Question 19

Causes gastritis and peptic ulcers (especially duodenal). Risk factor for peptic ulcer, gastric adenocarcinoma and lymphoma. Curved gram negative rod that is catalse, oxidase and urease + (can use urea breath test or fecal antigen test for diagnosis). Creates an alkaline environment.

• Define the organism
• What is the treatment?

Answer 19

• Helicobacter pylori
• Triple therapy:
  
  • PPI (proton pump inhibitor)
  • Clarithromycin
  • (either amoxicillin or metronidazole)

Question 20

• Define the 3 types of spirochetes (spiral shaped bacteria with axial filamnets)
• which one can be visualized
  
  • via aniline dyes in light microscope
  • dark-field microscopy

Answer 20

• Borrelia, Leptospira, Treponema
  
  • Aniline dyes: Borrelia
  • Dark field: Treponema

Question 21

Found in water with animal urine, causes leptospirosis; flu like symptoms jaundice, photophobia with conjunctial suffusion (erythema w/o exudate). Prevalent amon surfers and in tropics (Hawaii)

• What is the organism
• assocaited with what diesase?

Answer 21

• Leptospira interrogans
• Weil disease: (icterohemorrhagic leptospirosis) severe form with jaundice and azotemia from liver and kidney dysfunction; fever, hemorrhage and anemia.

Question 22

Common in northeastern US.

• inital symptoms: erythema chronicum migrans (bull’s eye rash’), flu like symptoms, +/- facial nerve palsy.
• later symptoms: monoarthrits (large joints) and migratory polyarthritis, cardiac (AV nodal block), neurologic (encephalopathy, facial nerve palsy, polyneuropathy).
• What is the disease and Caused by what
• Transmitted by what
• Treatment?

Answer 22

• **Lyme disease borrelia burgdorferi **
• transmitted by: Ixodes tick (vector of Babesia)
• Treatment: doxycycline, ceftriaxone.

Question 23

What is syphilis caused by?

Treatment?

Answer 23

• Treponema pallidum
• **Treatment: **Penicillin G

Question 24

Localized disease presenting with painless chancre. If avaloiabel use a dark field microscopy to visualze in fluid from chancre.

• What is the disease
• What is the serologic testing

Answer 24

• Primary syphilis
• VDRL/RPR (non specific) confirm diagnosis with (FTA-ABS specific)

Question 25

Disseminated disease with constitutional symptoms maculopapular rash (palms and soles) condylomata lata (also confirmable with bark field microscopy) * What is the disease * What is the serologic testing * Is it localized or systemic

Answer 25

* secondary syphilis * Serologic testing: VDRL/RPR (non specific, confirm diagnosis with specific test (FTA-ABS). * Systemic, latent syphilis follows.

Question 26

gummas (chroic granulomas) aortiis (vasa vasorum destruciton) neurosyphilis (tabes dorsalis, general paresis) Argyll Robertson pupil * What is the disease * What are the signs * What do you with neurosyphilis

Answer 26

* Tertiary syphilis * Signs: board based ataxia, + Romberg, Charcot joint, stroke w/o HTN. * For neurosyphilis: test spinal fluid with VDRL or RPR.

Question 27

Pt presents with saber shins, saddle nose, CN VIII deafness, Hutchinson teeth, mulberry molars. * What is the disease * How do you prevent

Answer 27

* **Congenital syphilis** * Prevent: treat mother early in pregnancy as placental transmission typically occurs after first trimester.

Question 28

What is argyll robertson pupil?

Answer 28

constricts wit accommodation but not reactive to light (assoc with 3 syphilis)

Question 29

What are VDRL false positives? What can cause it?

Answer 29

* VDRL detects nonspecific antibody that reacts with beef cardiolipin. * Inexpensive, widely available test for syphilis, quantitative, sensitive, but not specific. * Viruses (mono, hepatitis), Drugs, Rheumatic fever, Lupus and Leprosy.

Question 30

# Define a Jarisch-Herxherimer reaction what causes it?

Answer 30

* Flu like syndrome after antibiotics are started * due to killed bacteria releasing pyrogens.

Question 31

A pleomorphic gram variable rod that is involved in vaginosis. Presents as a gray vaginal discharge with fishy smell; nonpainful (vs vaginits). _Associated with sexual activity, but not sexually transmitted_. Clue cells coverd with certain bacteria are present under the microscope. * Define the organism * Treatment:

Answer 31

* Gardnerella vaginalis * Treatment: metronidazole or (to treat anaerobic bacteria) clindamycin

Question 32

what do you use to treat all rickettsial diseases and vector borne illness?

Answer 32

Doxycycline

Question 33

Disease occurs primarily in the sourht atlantic states, especially N. Carolina. Rash typically starts at wrist and ankeles and then spreads to teh truck, palms, and soles. *Classic triad: headache, fever, rash (vasculitis)* * Define the disease * Name the vector * describe what it is (obligate, facultative, etc.), and what it needs to synethesis ATP

Answer 33

* Rocky Mountain spotted fever * Rickettsia rickettsii * Obligate intracellular organism: NAD+ and CoA (due to the fact it can not synthesis ATP on its own). ## Footnote * -_Palms_ adn _soles_ rash is seen in Coxsackevirus A infection (hand, foot, mouth disease)* * -Rocky MSF & 2o syphilis (you drive _CARS_ using your _palms_ and _soles_)*

Question 34

Rash starts centerally and spreads out, sparing palms and soles * What is the disease? * Endemic is caused by what bug? * Epidemic is caused by what bug?

Answer 34

* Typhus * Endemic (fleas)--\> **R. typhi** * Epidemic (human body louse) **R. prowazekii** ## Footnote *Rickettsii on the wRists, Typhus on the Truck*

Question 35

Monocytes with morulae (berry like inclusions) in cytoplasm * what is the disease * what is the vector

Answer 35

* Ehrlichiosis * *Ehrlichia*

Question 36

Granulocytes wit h morulae in cytoplasm * What is the disease? * What is the vector?

Answer 36

* Anaplasmosis * Anaplasma

Question 37

A tick feces and cattle placenta release spores that are inhaled as aerosols. Presents as pneumonia. * What is the disease? * What is the vector? * What is the causitive organism?

Answer 37

* Q fever * No vector * Coxiella burnetti ## Footnote *Q fever is Queer b/c it has no rash or vector and its causitive organism can survive outside in its endospore form. Not in the Rickettsia genus, but closely related.*

Question 38

Chylamydiae cannot make their own ATP. They are obligate intracellular organisms that cause mucosal infections. What are the 2 forms (and their func) that chylamydiae come in?

Answer 38

* **Elementary body** (sm, dense) * Enfections & Enters cell via Endocytosis * transforms into reticulate body * **Reticulate body ** * Replicates in cell by _fission_ * reorganizes into elementary bodies

Question 39

What species of Chlamydia causes * reactive arthritis (Reiter syndrome) * follicular conjunctivitis * Nongonococcal urethritis and PID

Answer 39

*Chlamydia trachomatis*

Question 40

What 2 species of Chlamydia cause atypical pneumonia? How are they transmitted?

Answer 40

* *C. pneumonia & C. Psittaci* * transmitted by aerosal

Question 41

* What is the 2 types of treatments for Chlamydia (which on is favored and why) * Lab diagnosis? * how is this organism unusual?

Answer 41

* **Azithromycin** (favored b/c of one time treatment) and **Doxycycline** * **Lab diagnosis** cytoplasmic inclusions seen on Giemsa or fluorescent antibody- stained smear * **Unusual** Chlaymdial cell wall lacks muramic acid.

Question 42

What are the 3 *Chlamydia trachomatis* serotypes?

Answer 42

* Types A, B, & C * Types D-K * Types L1, L2, & L3

Question 43

Which of the *Chlamydia trachomatis *serotypes causes: * Chronic infection, causes blindness due to folllicular conjunctivitis in Africa.

Answer 43

* Types A, B, and C Africa/Blindness/Chronic infection

Question 44

Which of the Chlamydia trachomatis serotypes causes: * Urethritis/PID, ectopic pregnancy, neonatal pneumonia (staccato cough), neonatal conjunctivitis.

Answer 44

* Types D-K= everything else * neonatal disease can be acquired durign passage through infected birth canal. D\*\*K is where you would get the urethritis.

Question 45

Which of the Chlamydia trachomatis serotypes causes: * Small, painless uclers or genitals--\> swollen painful inguinal lymph nodes that ulcerate (buboes) * What is this termed as * How do you treat?

Answer 45

* Types L1, L2, L3 * Lymphogranuloma venerum * Treatment: doxycycline

Question 46

Pt presents with - Insidious onset, headache, nonproductive cough, patchy, or diffuse intersititial infiltrate. - X-ray looks worse than patient * What is the disease * High titer of what? * which can agglutinate or lyse RBC. * Grown on what? * Treated with what?

Answer 46

* *Mycoplasma pneumoniae* * high titer: cold agglutinins (IgM) * Grown on Eaton agar * **Treatment:** macrolides, doxycycline or fluoroquinolone *(penicillin ineffective since mycoplasma have no cell wall).*

Question 47

Mycoplasma * No cell wall. not seen on _ ._ * Bacterial membrane contains _ _ for stability * freq outbreaks in _ _ & _ ._ * Mycoplasmal pneumonia is more common in pts \<30 yrs old.

Answer 47

* Giesma stain * sterols * military recruits and prisons