Deck 40: Laboratory Considerations

Question 1

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.

Answer 1

C
Leptotrichia are very large fusiform rods with one pointed end and one blunt end.Colonies are large,gray,and convoluted.They are most often isolated from the oral cavity or urogenital tract.

Question 2

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)B.fragilis group.
D)Fusobacterium spp.

Answer 2

C
The characteristics listed can be used to describe the B.fragilis group.

Question 3

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).

Answer 3

D
Selective media are used to isolate certain anaerobes.Cultures for C.difficile are plated on CCFA,a special selective medium that helps inhibit normal gastrointestinal tract flora and allows the C.difficile to grow.

Question 4

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 5

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.

Question 6

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

A)the initial incubation period is at 35°C 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°C to 37°C for 24 hours.
D)thioglycollate broth can be inspected daily for 3 days.

Question 7

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.

Question 8

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

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

Question 9

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

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

Question 10

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)B.fragilis group.
D)Fusobacterium spp.

Question 11

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 12

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 13

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 14

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 15

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)B.ureolyticus.
D)Porphyromonas spp.

Question 16

Incubation conditions for anaerobic cultures include:

A)30°C 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 17

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 18

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

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

Question 19

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 20

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

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

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
Pigmented 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
B.fragilis group

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
Fusobacterium spp.