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A3 - Microbiology - Harr > 8.7 Anaerobic Bacteria > Flashcards

8.7 Anaerobic Bacteria Flashcards

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1
Q

Obligate anaerobes, facultative anaerobes, and microaerophiles are terms referring to bacteria that require:
A. Increased nitrogen
B. Decreased CO2
C. Increased O2
D. Decreased O2

A

D. Decreased O2

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2
Q

Which of the following most affects the oxidation-reduction potential (Eh, or redox potential) of media for anaerobic bacteria?
A. Oxygen
B. Nitrogen
C. pH
D. Glucose

A

C. pH

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3
Q

Which of the following is the medium of choice for the selective recovery of gram-negative anaerobes?
A. Kanamycin-vancomycin-anaerobe (KVA) agar
B. Phenylethyl alcohol (PEA) agar
C. Cycloserine cefoxitin fructose agar (CCFA)
D. THIO broth

A

A. Kanamycin-vancomycin-anaerobe (KVA) agar

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4
Q

Anaerobic bacteria are routinely isolated from all of the following types of infections except:
A. Lung abscesses
B. Brain abscesses
C. Dental infections
D. Urinary tract infections

A

D. Urinary tract infections

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5
Q

Methods other than packaged microsystems used to identify anaerobes include:
A. Antimicrobial susceptibility testing
B. Gas-liquid chromatography (GLC)
C. Special staining
D. Enzyme immunoassay

A

B. Gas-liquid chromatography (GLC)

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6
Q

Which broth is used for the cultivation of anaerobic bacteria to detect volatile fatty acids as an aid to identification?
A. Prereduced peptone-yeast extract-glucose (PYG)
B. THIO broth
C. Gram-negative (GN) broth
D. Selenite (SEL) broth

A

A. Prereduced peptone-yeast extract-glucose (PYG)

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7
Q

A gram-positive spore-forming bacillus growing on a sheep blood agar anaerobically produces a double zone of Beta-hemolysis and is positive for lecithinase. What is the presumptive identification?
A. Bacteroides ureolyticus
B. Bacteroides fragilis
C. Clostridium perfringens
D. Clostridium difficile

A

C. Clostridium perfringens

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8
Q

Egg yolk agar is used to detect which enzyme produced by several Clostridium species?
A. Lecithinase
B. Beta-Lactamase
C. Catalase
D. Oxidase

A

A. Lecithinase

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9
Q

Which of the following organisms will displays lipase activity on egg yolk agar?
A. Clostridium botulinum
B. Clostridium sporogenes
C. Clostridium novyi
D. All of these options

A

D. All of these options

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10
Q

Which spore type and location is found on Clostridium tetani?
A. Round, terminal spores
B. Round, subterminal spores
C. Ovoid, subterminal spores
D. Ovoid, terminal spores

A

A. Round, terminal spores

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11
Q

Gram-positive bacilli recovered from two blood cultures from a 60-year-old patient with diabetes gave the following results:

Spores seen = Neg
Hemolysis = + (double zone)
Motility = Neg
Lecithinase = +
Volatile acids by GLC (PYG) = acetic acid (A) and butyric acid (B)
What is the most likely identification?
A. Clostridium tetani
B. Clostridium perfringens
C. Clostridium novyi
D. Clostridium sporogenes

A

B. Clostridium perfringens

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12
Q

Which mechanism is responsible for botulism in infants caused by C. botulinum?
A. Ingestion of spores in food or liquid
B. Ingestion of preformed toxin in food
C. Virulence of the organism
D. Lipase activity of the organism

A

A. Ingestion of spores in food or liquid

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13
Q

The classic form of foodborne botulism is characterized by the ingestion of:
A. Spores in food
B. Preformed toxin in food
C. Toxin H
D. All of these options

A

B. Preformed toxin in food

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14
Q

Which test is performed to confirm an infection with C. botulinum?
A. Toxin neutralization test
B. Spore-forming test
C. Lipase test
D. Gelatin hydrolysis test

A

A. Toxin neutralization test

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15
Q

Which Clostridium spp. causes pseudomembranous colitis or antibiotic-associated colitis?
A. Clostridium ramosum
B. Clostridium difficile
C. Clostridium perfringens
D. Clostridium sporogenes

A

B. Clostridium difficile

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16
Q

Identification of C. tetani is usually based on:
A. Gram staining of the wound site
B. Anaerobic culture of the wound site
C. Blood culture results
D. Clinical findings

A

D. Clinical findings

17
Q

Obligate anaerobic gram-negative bacilli that do not form spores, grow well in 20% bile (Bacteroides bile esculin [BBE] agar), and are resistant to penicillin two-unit disks are most likely:
A. Porphyromonas spp.
B. Bacteroides spp.
C. Fusobacterium spp.
D. Prevotella spp.

A

B. Bacteroides spp.

18
Q

Which Bacteroides spp. is noted for “pitting” of the agar and is sensitive to penicillin two-unit disks?
A. Bacteroides vulgatus
B. Bacteroides ovatus
C. Bacteroides thetaiotamicron
D. Bacteroides ureolyticus

A

D. Bacteroides ureolyticus

19
Q

Which gram-negative bacilli produce brown to black pigment on KVA agar and brick red fluorescence when exposed to an ultraviolet (UV) light source?
A. Porphyromonas spp. and Prevotella spp.
B. Fusobacterium spp. and Actinomyces spp.
C. Bacteroides spp. and Fusobacterium spp.
D. All of these options

A

A. Porphyromonas spp. and Prevotella spp.

20
Q

The following characteristics of an obligate anaerobic gram-negative bacilli best describe which of the listed genera?

Gram staining = Long, slender rods w/ pointed ends
Colonial appearance = Dry bread crumbs or “fried-egg” appearance
Penicillin two-unit disks test = Susceptible

A. Bacteroides spp.
B. Fusobacterium spp.
C. Prevotella spp.
D. Porphyromonas spp.

A

B. Fusobacterium spp.

21
Q

All of the following genera are anaerobic cocci that stain gram positive except:
A. Peptococcus spp.
B. Peptostreptococcus spp.
C. Streptococcus spp.
D. Veillonella spp.

A

D. Veillonella spp.

22
Q

The gram-positive non-spore-forming, anaerobic, short, pleomorphic rods most frequently recovered from blood cultures as a contaminant are:
A. Propionibacterium acnes
B. Clostridium perfringens
C. Staphylococcus intermedius
D. Veillonella parvula

A

A. Propionibacterium acnes

23
Q

Which Clostridium species is most often recovered from a wound infection with gas gangrene?
A. Clostridium sporogenes
B. Clostridium sodellii
C. Clostridium novyi
D. Clostridium perfringens

A

D. Clostridium perfringens

24
Q

Gram staining of a smear taken from the periodontal pockets of a 30-year-old man with poor dental hygiene showed sulfur granules containing gram-positive rods (short diphtheroids and some unbranched filaments) and were non-acid fast. Colonies on blood agar resembled “molar teeth” in formation. The most likely organism is:
A. Actinomyces israelii
B. Propionibacterium acnes
C. Staphylococcus intermedius
D. Peptostreptococcus anaerobius

A

A. Actinomyces israelii

25
Q

Antimicrobial susceptibility testing of Bacteroides and Clostridium spp. anaerobes are done by which of the following methods?
A. Broth microdilution
B. Agar dilution
C. E-Test
D. All of the above

A

D. All of the above

26
Q

An abdominal postoperative wound specimen grew catalase-positive, indole-negative, nonpigmented, nonfluorescent, gram-negative, pleomorphic bacilli (safety pin-shaped) on 20% bile media. The colonies also grew on KVA agar (resistant to kanamycin, vancomycin, and colistin). What is the most likely identification?
A. Fusobacterium nucleatum
B. Bacteroides fragilis
C. Prevotella spp.
D. Porphyromonas spp.

A

B. Bacteroides fragilis

A3 - Microbiology - Harr (12 decks)

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