Deck 41: Overview of Anaerobic Organisms

Question 1

A diabetic patient has developed gas gangrene of the right foot.The most likely anaerobe causing this infection is:

A) Clostridium tetani.
B) C. perfringens.
C) C. botulinum.
D) C. difficile.

Answer 1

B
Of the Clostridium species listed, C.perfringens is capable of causing gas gangrene in diabetic patients as a result of the loss of circulation in the extremities caused by diabetes.

Question 2

The most likely identification of a bile-sensitive, kanamycin-resistant, catalase-negative, and indole-negative anaerobic gram-negative bacilli is:

A) nonpigmented Prevotella.
B) Porphyromonas spp.
C) Bacteroides fragilis group.
D) pigmented Prevotella.

Answer 2

A
The characteristics listed can be used to describe nonpigmented Prevotella.

Question 3

Characteristics that strongly indicate the presence of pigmented Prevotella or Porphyromonas in a clinical specimen include:

A) yellow-green fluorescence.
B) rhizoid margins resembling a "Medusa head" on anaerobic blood agar.
C) brick-red fluorescence under long-wavelength ultraviolet (UV) light.
D) chartreuse fluorescens.

Answer 3

C
Characteristics of anaerobes may sometimes be evident in the specimens that contain the organisms.Characteristics that strongly indicate the presence of anaerobes include a foul odor; sulfur granules associated with Actinomyces spp., Propionibacterium spp., or Eubacterium nodatum; and brick-red fluorescence under long-wavelength UV light associated with pigmented Prevotella or Porphyromonas.

Question 4

In a clinical specimen, sulfur granules strongly indicate the presence of which anaerobe?

A) Actinomyces spp.
B) Bacteroides spp.
C) Prevotella spp.
D) Clostridia spp.

Question 5

Optimal recovery and identification of anaerobic bacteria in clinical specimens occurs when:

A) the initial incubation period is at 35° to 37° C for 48 hours.
B) plates are incubated for at least 3 days before discarding as negative.
C) the initial incubation period is at 35° to 37° C for 24 hours.
D) thioglycollate broth can be inspected daily for 3 days.

Question 6

Quality control is set up on a new lot of an indole reagent.Clostridium bifermentans and Clostridium bolteae are used, and the following results are obtained: • C.bifermentans: positive
• C.bolteae: negative
Which one of the following statements explains this discrepancy?

A) The reagent is most likely expired.
B) The incubation time is most likely abbreviated.
C) These two organisms are poor choices; both are indole-positive.
D) No discrepancy is present. The results obtained are correct.

Question 7

The primary plating medium used to select out Clostridia spp.would be:

A) anaerobic blood agar.
B) laked kanamycin-vancomycin (LKV) blood agar.
C) phenylethyl alcohol agar (PEA).
D) thioglycollate.

Question 8

The most likely identification of a bile-resistant, kanamycin-resistant, colistin-resistant, and vancomycin-resistant anaerobic gram-negative bacilli is:

A) nonpigmented Prevotella.
B) Porphyromonas spp.
C) Bacteroides fragilis group.
D) Fusobacterium spp.

Question 9

Incubation conditions for anaerobic cultures include:

A) 30° to 35° C.
B) incubation for 48 hours before exposing the culture to air.
C) incubation for at least 3 days before discarding.
D) aerobic incubation of the broth medium with the cap loose.

Question 10

The most likely identification of an anaerobic gram-positive coccus that is resistant to metronidazole is:

A) Streptococcus.
B) Peptostreptococcus.
C) Leptotrichia.
D) Peptococcus.

Question 11

MATCHING
Match the description to the most likely identification.
a.Are kanamycin-resistant, colistin-resistant, and vancomycin-resistant and grow in 20% bile
b.Are bile-sensitive, kanamycin-resistant, catalase-negative, and indole-negative
c.Fluoresce brick red or have a brown-to-black pigment
d.Reduces nitrate, and requires formate and fumarate for growth in broth culture
e.Are sensitive to kanamycin, and fluoresce a chartreuse color
Bacteroides ureolyticus

Question 12

The most likely identification of an anaerobic gram-negative bacilli that will fluoresce brick red or has a brown-to-black-pigment is:

A) nonpigmented Prevotella.
B) Porphyromonas spp.
C) Bacteroides fragilis group.
D) Fusobacterium spp.

Question 13

The ethanol shock or heat shock test will separate which two bacteria?

A) Clostridium perfringens and Clostridium ramosum
B) Clostridium and Bifidobacterium
C) Actinomyces and Bifidobacterium
D) Eubacterium and Eggerthella

Question 14

The most likely identification of an anaerobic gram-negative bacillus that reduces nitrate and requires formate and fumarate for growth in broth culture is:

A) Porphyromonas spp.
B) Bacteroides ureolyticus.
C) pigmented Prevotella.
D) Fusobacterium spp.

Question 15

The most likely identification of an anaerobic gram-positive bacillus that produces spores is:

A) Bifidobacterium.
B) Eubacterium.
C) Eggerthella.
D) Clostridium.

Question 16

The most likely identification of an anaerobic, curved, gram-variable bacillus with tapered ends on Gram stain of vaginal secretions when vaginosis is suggested is:

A) Porphyromonas spp.
B) Actinomyces.
C) Mobiluncus.
D) Fusobacterium spp.

Question 17

The most likely identification of an anaerobic gram-negative coccus is:

A) Porphyromonas spp.
B) Veillonella.
C) Leptotrichia.
D) Fusobacterium spp.

Question 18

The most likely identification of kanamycin-sensitive and anaerobic gram-negative bacilli that fluoresce a chartreuse color is:

A) Fusobacterium spp.
B) nonpigmented Prevotella.
C) Bacteroides ureolyticus.
D) Porphyromonas spp.

Question 19

Fecal cultures to isolate Clostridium difficile are plated on:

A) anaerobic blood agar.
B) LKV blood agar.
C) aerobic 5% sheep blood agar.
D) cycloserine cefoxitin fructose agar (CCFA).

Question 20

The most likely identification of an anaerobic gram-positive bacillus that is a very large fusiform bacillus with one pointed end and one blunt end is:

A) Eubacterium.
B) Veillonella.
C) Leptotrichia.
D) Propionibacterium.

Question 21

MATCHING
Match the description to the most likely identification.
a.Are kanamycin-resistant, colistin-resistant, and vancomycin-resistant and grow in 20% bile
b.Are bile-sensitive, kanamycin-resistant, catalase-negative, and indole-negative
c.Fluoresce brick red or have a brown-to-black pigment
d.Reduces nitrate, and requires formate and fumarate for growth in broth culture
e.Are sensitive to kanamycin, and fluoresce a chartreuse color
Nonpigmented Prevotella

Question 22

MATCHING
Match the description to the most likely identification.
a.Are kanamycin-resistant, colistin-resistant, and vancomycin-resistant and grow in 20% bile
b.Are bile-sensitive, kanamycin-resistant, catalase-negative, and indole-negative
c.Fluoresce brick red or have a brown-to-black pigment
d.Reduces nitrate, and requires formate and fumarate for growth in broth culture
e.Are sensitive to kanamycin, and fluoresce a chartreuse color
Porphyromonas spp.

Question 23

MATCHING
Match the description to the most likely identification.
a.Are kanamycin-resistant, colistin-resistant, and vancomycin-resistant and grow in 20% bile
b.Are bile-sensitive, kanamycin-resistant, catalase-negative, and indole-negative
c.Fluoresce brick red or have a brown-to-black pigment
d.Reduces nitrate, and requires formate and fumarate for growth in broth culture
e.Are sensitive to kanamycin, and fluoresce a chartreuse color
Pigmented Prevotella

Question 24

MATCHING
Match the description to the most likely identification.
a.Are kanamycin-resistant, colistin-resistant, and vancomycin-resistant and grow in 20% bile
b.Are bile-sensitive, kanamycin-resistant, catalase-negative, and indole-negative
c.Fluoresce brick red or have a brown-to-black pigment
d.Reduces nitrate, and requires formate and fumarate for growth in broth culture
e.Are sensitive to kanamycin, and fluoresce a chartreuse color
Fusobacterium spp.

Question 25

MATCHING
Match the description to the most likely identification.
a.Are kanamycin-resistant, colistin-resistant, and vancomycin-resistant and grow in 20% bile
b.Are bile-sensitive, kanamycin-resistant, catalase-negative, and indole-negative
c.Fluoresce brick red or have a brown-to-black pigment
d.Reduces nitrate, and requires formate and fumarate for growth in broth culture
e.Are sensitive to kanamycin, and fluoresce a chartreuse color
Bacteroides fragilis group