MICRO Flashcards
1
Q
- Spores are found in select groups of bacteria. Which of the following statements describes the major advantage to the bacteria that possess these structures?
a. Spores are resistant to heat, cold, drying, most chemicals, and boiling
b. Spores allow an organism to better control its local environment
c. Spores allow bacteria to attach or adhere to host tissues
d. Organisms with spores have a more efficient exchange of genetic material
A
c
2
Q
- Choose the binomial name that is correctly written.
a. Staphylococcus Aureus
b. Staphylococcus species aureus
c. Staphylococcus aureus
d. Staphylococcus aureus
A
c
3
Q
- Fermentation end-products are often used to aid in the identification of bacteria. Fermentation results in which of the following?
a. Conversion of glucose to pyruvate
b. Lactic acid, mixed acids, alcohols, CO2
production
c. CO2 and water
d. Specific teichoic acids
A
b
4
Q
- The exchange of cellular DNA between two living bacterial cells that involves an intercellular bridge is which of the following processes?
a. Transformation
b. Transduction
c. Plasmidization
d. Conjugation
A
d
5
Q
- Transduction is defined as which of the following?
a. The change of the bacterial genotypes through the exchange of DNA from one cell to another
b. An internal change in the original nucleotide sequence of a gene or genes within an organism’s genome
c. The process by which genetic elements such as plasmids and transposons excise from one genomic location and insert into another
d. A mechanism that is mediated by viruses, by which DNA from two bacteria may come together in one cell, thus allowing for recombination
A
d
6
Q
- A mordant that is applied after the primary stain to chemically bond the alkaline dye to the bacterial cell wall is which of the following?
a. Safranin
b. Crystal violet
c. Gram’s iodine
d. Gram’s decolorizer
A
c
7
Q
- Which of the following bacteria should be considered important pathogens when reading gram-stained smears of soft tissue abscess?
a. Streptococcus pneumoniae
b. Neisseria gonorrhoeae
c. Pseudomonas aeruginosa
d. Staphylococcus aureus
A
d
8
Q
- The most appropriate interpretation of a gram-stained smear of a sputum specimen would be which of the following? (gram-stained smear, 400x).
a. Few epithelial cells, many PMNs
b. Inadequate specimen, do not culture for anaerobes
c. Many cells, many gram-positive cocci in pairs and chains
d. More than 25 epithelial cells, probable oral contamination, suggest recollect
A
d
9
Q
- 85% N2, 10% H2, 5% CO2 is the environmental condition that best suits which type of organism?
a. Aerobes
b. Anaerobes
c. Capnophiles
d. Microaerophiles
A
b
Microaerophilic: 5% O2, 10% CO2, 85% N
Anaerobic: 85% N2, 10% H2, 5% CO2
10
Q
- Which medium can be described as containing bile salts and dyes (bromothymol blue and acid fuchsin) to selectively slow the growth of most nonpathogenic gram-negative bacilli found in the gastrointestinal tract and allow Salmonella spp. and Shigella spp. to grow?
a. Thayer-Martin
b. MacConkey
c. PEA (phenylethyl alcohol)
d. Hektoen
A
d
11
Q
- Choose the group of bacteria that is described as catalase-positive, gram-positive cocci that grow facultatively anaerobic and that form grapelike clusters.
a. Neisseria spp.
b. Rothia (Stomatococcus) spp.
c. Staphylococcus spp.
d. Micrococcus spp.
A
c
12
Q
- The slide coagulase test is a rapid screening test for the production of which of the following?
a. Clumping factor
b. Free coagulase
c. Extracellular coagulase
d. Catalase
A
a
13
Q
- The first identification test performed on a clinical isolate of gram-positive, catalase-positive cocci should be which of the following?
a. Penicillin test
b. Gram stain
c. Oxidase test
d. Coagulase test
A
d
14
Q
- The Staphylococcus sp. that is more likely to cause uncomplicated urinary tract infections in nonhospitalized hosts, especially sexually active young women, is which of the following?
a. Staphylococcus saprophyticus
b. Staphylococcus aureus
c. Staphylococcus epidermidis
d. Staphylococcus intermedius
A
a
15
Q
- The toxic shock syndrome toxin-1 is an important virulence factor in staphylococcal disease. This toxin is classified into which of the following groups of toxins?
a. Cytolytic toxin
b. Leukocidin
c. Phospholipase
d. Enterotoxin
A
d
16
Q
- Mannitol salt agar is selective and differential for which group of organisms?
a. Staphylococcus spp.
b. Enterococcus spp.
c. Gram-positive cocci
d. Streptococcus spp.
A
a
17
Q
- Within 5 hours of returning home from lunch at your most favorite fast food restaurant you feel very sick and are vomiting. Which of the following is the most likely causative organism?
a. Staphylococcus aureus
b. Vibrio parahaemolyticus
c. Shigella sonnei
d. Escherichia coli
A
a
18
Q
- The bacterial species that can be described as susceptible to bile and optochin, a-hemolytic, a major cause of bacterial meningitis, and often carrying an antiphagocytic capsule is which of the following?
a. Enterococcus faecalis
b. Streptococcus pneumoniae
c. Streptococcus pyogenes
d. Streptococcus agalactiae
A
b
19
Q
- The bacterial species that can be described as susceptible to penicillin and bacitracin, b-hemolytic, a major cause of bacterial pharyngitis, and often carrying an antiphagocytic M protein is which of the following?
a. Enterococcus faecalis
b. Streptococcus pyogenes
c. Streptococcus agalactiae
d. Viridans streptococci
A
b
19
Q
- The rapid antigen detection methods for throat swabs used for screening patients for streptococcal pharyngitis can be best described by which of the following statements?
a. They can be useful in quickly identifying most cases of streptococcal pharyngitis
b. They are a quick way to rule out streptococcal pharyngitis and avoid giving antibiotics when not needed
c. They are always very sensitive and specific for streptococcal pharyngitis
d. They are a quick and accurate way to diagnose bacterial and viral pharyngitis
A
a
19
Q
- The bacterial species that can be described as able to hydrolyze hippurate, b-hemolytic, a major cause of neonatal meningitis and sepsis, and producer of the CAMP factor is which of the following?
a. Streptococcus pneumoniae
b. Streptococcus pyogenes
c. Streptococcus agalactiae
d. Viridans streptococci
A
c
19
Q
- The hemolysis of this Streptococcus spp. would best be described as which of the following? (color plate 2)
a. β-Hemolysis
b. γ-Hemolysis
c. α-Hemolysis
d. k-Hemolysis
A
c
20
Q
- Enterococcus spp. can be differentiated from most Streptococcus spp. by which of the following tests?
a. Growth in presence of 6.5% salt
b. Production of catalase
c. Production of coagulase
d. Growth on PEA medium
A
a
21
Q
- A pure culture of a b-hemolytic Streptococcus sp. recovered from a leg ulcer gave the following reactions:
CAMP test = Negative
Hippurate hydrolysis = Negative
Bile esculin slant = No growth
6.5% Salt = No growth
PYR = Negative Bacitracin = Resistant
Optochin = Resistant SXT = Sensitive
Which of the following is the most likely identification of this organism?
a. Streptococcus pyogenes
b. Streptococcus agalactiae
c. Enterococcus faecalis
d. Streptococcus sp., not groups A, B, or D
A
d
22
Q
- The ability to grow well at refrigerator temperatures is a characteristic of which of the following organisms?
a. Mycobacterium gordonae
b. Listeria monocytogenes
c. Erysipelothrix
d. Bacillus cereus
A
b
23
Q
- A catalase-positive, gram-positive bacillus that is not acid-fast, does not branch, and does not form spores could possibly belong to which group of bacteria?
a. Corynebacterium
b. Bacillus
c. Nocardia
d. Mycobacterium
A
a
24
Q
- A throat culture was taken from a 6-year-old boy with a gray pseudomembrane covering his oropharynx. A catalase-positive organism was isolated on cysteine-tellurite medium and subcultured to Tinsdale medium, where it grew as black colonies
with brown halos. A Gram stain was performed on these colonies. Which of the following cellular morphologies was most likely seen?
a. Gram-positive branching bacilli
b. Gram-positive cocci in short chains
c. Gram-positive bacilli in irregular clublike
shape
d. Gram-positive cocci in grapelike clusters
A
c
25
Q
- A blood culture is positive for gram-positive bacilli that gave the following growth characteristics and biochemical reactions:
MacConkey agar: No growth
Catalase: Positive
H2S on TSI: negative
Growth of blood agar, nonhemolytic
Nonmotile No spores
These reactions are consistent with which of the following organisms?
a. Listeria spp.
b. Group B β Streptococcus
c. Erysipelothrix spp.
d. Corynebacterium spp.
A
d
26
Q
- A skin lesion was opened and drained in surgery. The culture was positive for a gram-positive bacillus, which gave the following growth characteristics and biochemical reactions:
MacConkey agar: No growth
Catalase: Negative
H2S on TSI: Positive
Growth of blood agar, nonhemolytic
Nonmotile No spores
These reactions are consistent with which of the following organisms?
a. Listeria spp.
b. Group B b Streptococcus
c. Erysipelothrix spp.
d. Corynebacterium spp.
A
c
27
Q
- Which of the following sets of tests provide the best differentiation of Erysipelothrix from Listeria monocytogenes?
a. Gram-stained smear, oxidase, and optochin
b. Gram-stained smear, catalase, and motility
c. CAMP test, hydrogen sulfide production, esculin hydrolysis
d. Reverse CAMP, gram-stained smear, β-hemolysis
A
c
28
Q
- Neonatal meningitis is an uncommon but significant disease. Two important causes of
this disease may be somewhat difficult to differentiate on preliminary observation. Which of the following sets of tests provide the best differentiation of Streptococcus agalactiae from Listeria monocytogenes?
a. Gram-stained smear, oxidase, and optochin
b. Gram-stained smear, catalase, and motility
c. CAMP test, hydrogen sulfide production,
b-hemolysis
d. Reverse CAMP, gram-stained smear, β-hemolysis
A
b
29
Q
- Which of the following tests is important as a part of the genus identification or as part of a preliminary identification but is not used as a confirmatory identification of Bacillus anthracis?
a. Demonstration of a capsule
b. Demonstration of spore formation
c. Positive PCR test
d. Lysis of the strain by specific bacteriophages
A
b
30
Q
- Bacillus anthracis and Bacillus cereus can be differentiated in the laboratory by a variety of different test results. Which of the following sets of tests best differentiate these two species?
a. Catalase and glucose fermentation
b. Motility and lecithinase production
c. Oxidase and b-hemolysis on 5% sheep blood agar
d. Motility and b-hemolysis on 5% sheep blood agar
A
d
31
Q
- Which of the following specimens would be best for identifying Bacillus cereus as the cause of an outbreak of food poisoning?
a. Blood
b. Rectal swabs
c. Stool samples
d. Food
A
d
32
Q
- A first morning sputum sample is received for acid fast culture. The specimen is centrifuged, and the sediment is inoculated on two Lowenstein-Jensen slants that are incubated at 35°C with 5% to 10% CO2. After 1 week, the slants show abundant growth over the entire surface. Stains reveal gram-negative bacilli. Which of the following should be done to avoid this problem?
a. Use a medium specifically designed for the
growth of AFB
b. Dilute out the sediment before inoculation with saline
c. Decontaminate the specimen with NALC–
sodium hydroxide mixture
d. Incubate the tubes at room temperature to retard bacterial growth
A
c
33
Q
- A patient recently arrived in the United States from Africa presents with a long-standing cutaneous lesion, which is cultured for bacteria, fungi, and AFB. An AFB smear is made and is reported as positive for AFB. After 8 weeks of culture on both nonselective and selective AFB media, no colonies appear. Which of the following organisms should
be suspected?
a. M. kansasii
b. M. tuberculosis
c. M. leprae
d. M. avium-intracellulare complex
A
c
34
Q
- The mycobacterial species that occur in humans and belong to the M. tuberculosis complex include which of the following?
a. M. tuberculosis, nontuberculous Mycobacteria, M. bovis, and M. africanum
b. M. tuberculosis, M. gordonae, M. bovis BCG, and M. africanum
c. M. tuberculosis, M. bovis, M. avium, and M.
intracellulare
d. M. tuberculosis, M. bovis, M. bovis BCG, and M. africanum
A
d
35
Q
- The Runyon system of classification is based on which of the following?
a. Colony and microscopic morphology
b. Biochemical characteristics
c. Growth rate and colonial pigmentation
d. All of the above are correct
A
c
36
Q
- In identification of mycobacterial isolates, the Tween 80 test involves which of the following?
a. An enzyme that is able to produce Tween
80 from certain ingredients found in the
medium
b. Lipase that is able to hydrolyze polyoxyethylene sorbitan monooleate into oleic acid and polyoxyethylated sorbitol
c. The metabolism of niacin to nicotinic acid by enzymatic action
d. Testing the isolate for susceptibility to
Tween 80
A
b
37
Q
- The gram-negative bacillus that can be described as oxidase-negative, nitrate-positive, indole-negative, citrate-positive, methyl red–positive, urease-negative, and H2S-positive is most likely which of
the following?
a. Klebsiella pneumoniae
b. Salmonella enteritidis
c. Escherichia coli
d. Shigella sonnei
A
b