Micro 8.6 Aerobic Gram-Positive Rods, Spirochetes, Mycoplasmas and Ureaplasmas, and Chlamydiae Flashcards
- Large, gram-positive, spore-forming rods growing on blood agar as large, raised, β-hemolytic colonies that spread and appear as frosted green-gray glass are most likely:
A. Pseudomonas spp.
B. Bacillus spp.
C. Corynebacterium spp.
D. Listeria spp.
B. Bacillus spp.
- Bacillus anthracis and Bacillus cereus can best be differentiated by which tests?
A. Motility and β-hemolysis on a blood agar plate
B. Oxidase and β-hemolysis on a blood agar plate
C. Lecithinase and glucose
D. Lecithinase and catalase
A. Motility and β-hemolysis on a blood agar plate
- Which is the specimen of choice for proof of food poisoning by B. cereus?
A. Sputum
B. Blood
C. Stool
D. Food
D. Food
The best specimen is the suspected food itself. Stool cultures are not useful because B. cereus is part of the normal fecal flora. The suspected food can be the source of food poisoning by B. cereus if 100,000 or greater organisms per gram of infected food are demonstrated.
- A suspected B. anthracis culture obtained from a wound specimen produced colonies that had many outgrowths (Medusa-head appearance), but were not β-hemolytic on sheep blood agar. Which test should be performed next?
A. Penicillin (10-unit) susceptibility test
B. Lecithinase test
C. Glucose test
D. Motility test
A. Penicillin (10-unit) susceptibility test
- Which of the following tests should be performed for initial differentiation of L. monocytogenes from group B streptococci?
A. Gram stain, motility at room temperature, catalase
B. Gram stain, CAMP test, H2S/TSI
C. Oxidase, CAMP test, glucose
D. Oxidase, bacitracin
A. Gram stain, motility at room temperature, catalase
- Culture of a finger wound specimen from a meat packer produced short gram-positive, non–spore-forming bacilli on a blood agar plate showing no hemolysis. Given the following test results at 48 hours, what is the most likely identification?
Catalase = Neg
H2S/TSI = +
Motility (wet prep) = Neg
Motility (gel media 22 oC) = + (bottle-brush growth in stab culture)
A. Bacillus cereus
B. Listeria monocytogenes
C. Erysipelothrix rhusiopathiae
D. Bacillus subtilis
C. Erysipelothrix rhusiopathiae
- Nonspore-forming, slender, gram-positive, rod-forming palisades and chains were recovered from a vaginal culture and grew well on tomato juice agar. The most likely identification is:
A. Lactobacillus spp.
B. Bacillus spp.
C. Neisseria spp.
D. Streptococcus spp.
A. Lactobacillus spp.
- A Corynebacterium species recovered from a throat culture is considered a pathogen when it produces:
A. A pseudomembrane of the oropharynx
B. An exotoxin
C. Gray-black colonies with a brown halo on Tinsdale agar
D. All of these options
D. All of these options
- A presumptive diagnosis of Gardnerella vaginalis can be made using which of the following findings?
A. Oxidase and catalase tests
B. Pleomorphic bacilli heavily colonized on vaginal epithelium
C. Hippurate hydrolysis test
D. All of these options
D. All of these options
- A gram-positive branching filamentous organism recovered from a sputum specimen was found to be positive with a modified acid-fast stain method. What is the most likely presumptive identification?
A. Bacillus spp.
B. Nocardia spp.
C. Corynebacterium spp.
D. Listeria spp.
B. Nocardia spp.
- Routine laboratory testing for Treponema pallidum involves:
A. Culturing
B. Serological analysis
C. Acid-fast staining
D. Gram staining
B. Serological analysis
- Spirochetes often detected in the hematology laboratory while scanning a blood film, even before the physician suspects the infection, are:
A. Borrelia spp.
B. Treponema spp.
C. Campylobacter spp.
D. Leptospira spp.
A. Borrelia spp.
- Which of the following organisms is the cause of Lyme disease?
A. Treponema pallidum
B. Neisseria meningitidis
C. Babesia microti
D. Borrelia burgdorferi
D. Borrelia burgdorferi
- The diagnostic method most commonly used for the identification of Lyme disease is:
A. Serology
B. Culture
C. Gram staining
D. Acid-fast staining
A. Serology
- Primary atypical pneumonia is caused by:
A. Streptococcus pneumoniae
B. Mycoplasma pneumoniae
C. Klebsiella pneumoniae
D. Mycobacterium tuberculosis
B. Mycoplasma pneumoniae