Microbiology: Clinial Bacteriology Flashcards
(396 cards)
How would you differentiate Pseudomonas from other nonlactose fermenters?
It is oxidase positive, other nonlactose fermenters are oxidase ⊖
What differentiates Q fever from the diseases of the Rickettsia genus, to which it is closely related?
Coxiella burnetii, the causative agent of Q fever, can survive outside in endospore form; there is no rash or vector
What 2 mycobacterial species are usually resistant to multiple drugs?
M tuberculosis and M avium–intracellulare
A patient has a Haemophilus infection. By what route was it likely acquired?
Respiratory tract
A young woman presents with nonpainful, gray vaginal discharge. You suspect Gardnerella. What outcome do you expect on an amine whiff test?
A strong fishy odor; mixing the discharge with 10% potassium hydroxide (KOH) solution in an amine whiff test for G vaginalis enhances its odor
Antibodies to which virulent component of Streptococcus pyogenes can give rise to rheumatic fever?
M protein (antibodies enhance host defense, but can give rise to rheumatic fever)
What cutaneous manifestations are likely if a patient has a history of syphilis?
A maculopapular rash on palms and soles, condylomata lata (smooth, painless, wart-like lesions on genitalia), and patchy hair loss (features of secondary syphilis)
What 2 outcomes could be expected after a primary tuberculosis infection?
90%: recovery (fibrous healing/calcification, PPD test ⊕); <10%: progressive primary TB (seen in patients with AIDS or malnutrition)
What organism is the 2nd most common cause of uncomplicated urinary tract infection (UTI) in young women?
Staphylococcus saprophyticus
What vaccinations could have prevented a 12-year-old boy’s infection with a gram ⊖ aerobic coccobacillus?
The Tdap or DTaP vaccines would have protected against Bordetella pertussis infection
What are the virulence factors produced by Pseudomonas aeruginosa?
Phospholipase C; Endotoxin; Exotoxin A; Pigments: pyoverdine and pyocyanin (blue-green pigment; generates reactive oxygen species); produces PEEP
You visualize a spirochete using light microscopy with an aniline dye (Wright or Giemsa stain). What is it?
Borrelia (Borrelia is Big); due to size, this is the only spirochete visible on light microscopy
What type of hemolysis is induced by Enterococcus species?
Enterococcus species exhibit variable hemolysis
Is a VDRL test better for screening or confirmation of syphilis?
Screening; VDRL is considered sensitive but not specific; often used for initial screening and is widely available
Name an aerobic, gram ⊕, acid-fast branching filament.
Nocardia
What pyogenic illnesses are caused by Streptococcus pyogenes?
Pharyngitis, erysipelas, impetigo (“honey-crusted” lesions), cellulitis
What types of bacteria grow pink colonies on MacConkey agar?
Lactose-fermenting enteric: Citrobacter, Klebsiella, E coli, Enterobacter, Serratia (Lactose is key; test with MacConKEE’S agar)
What immunologic diseases result from Streptococcus pyogenes pharyngitis?
Rheumatic fever, glomerulonephritis (“Phyogenes pharyngitis can result in rheumatic “phever” and glomerulonephritis)
Reptiles and poultry are the animal hosts of what pathogen that causes a diarrheal illness?
Salmonella spp (exception: S typhi)
How is Campylobacter jejuni transmitted?
Fecal-oral transmission (eg, pet feces, contaminated food, contact with hands of infected persons)
What do patients with Salmonella and Shigella have in common with their clinical presentation?
Both Salmonella and Shigella often cause bloody diarrhea (note that S typhi diarrhea is often preceded by constipation)
What are the symptoms of Q fever?
Headache, cough, flu-like symptoms, pneumonia, possibly with hepatitis; may also present as culture ⊖ endocarditis
A patient is diagnosed with bacterial vaginosis secondary to Gardnerella vaginalis. What do you expect to see on wet prep?
Clue cells or vaginal epithelial cells covered with bacteria (stippled appearance along outer margins)
How would a patient with Weil disease (icterohemorrhagic leptospirosis) present?
Severe form of leptospirosis that presents with elevated bilirubin and creatinine levels, fever, hemorrhage, and low hemoglobin level