Deck 16: Aerobic Gram-Positive Bacilli

Question 1

What is the colony morphology of A. haemolyticum on SBA?

A) A narrow zone of $\beta$ -hemolysis and a black opaque dot is seen when the colony is scraped away.
B) No hemolysis, with pitting around the edges of the colony.
C) $\alpha$ -Hemolysis, with a central black opaque dot in the colony.
D) A wide zone of $\beta$ -hemolysis and a large, yellow, mucoid colony.

Answer 1

A narrow zone of $\beta$ -hemolysis and a black opaque dot is seen when the colony is scraped away.

Question 2

What is the major virulence factor associated with Corynebacterium diphtheriae?

A) Trypsin
B) Diphtheria toxin
C) Diphtheria bacteriophage
D) Hyaluronidase

Answer 2

B

Question 3

What media does Corynebacterium diphtheriae grow on?

A) Sheep blood agar (SBA)
B) Loeffler
C) Cystine-tellurite blood
D) All of the above

Answer 3

D

Question 4

One of the foremen at a pig farm notices purple sores on one of his workers. The worker has not been feeling well for the past 2 weeks, so the foreman sends him to the physician. The physician takes scrapings from the lesions and sends them to the laboratory for a culture. The Gram stain shows 3+ thin, gram-positive rods that have filaments. The culture plates were examined the next day and revealed nonhemolytic, pinpoint, transparent colonies. What is the most likely pathogen?

A) Streptococcus pneumoniae
B) Streptococcus pyogenes
C) Erysipelothrix rhusiopathiae
D) Rhodococcus

Question 5

All the following are general characteristics of the genus Bacillus, except

A) aerobic or facultative anaerobes.
B) gram-positive.
C) form endospores.
D) cocci.

Question 6

Several people from a picnic came down with a gastrointestinal disturbance, and public health officials suspected a case of food poisoning. The food was cultured, and after 24 hours of incubation the hot dogs yielded growth on SBA of small, round, smooth, translucent colonies surrounded by a narrow zone of $\beta$ -hemolysis. A Gram stain showed gram-positive coccobacilli. Motility medium was inoculated and an umbrella pattern of motility was observed at room temperature. What organism was isolated as the cause of the illness?

A) Listeria monocytogenes
B) Rhodococcus equi
C) Rothia dentocariosa
D) Corynebacterium diphtheriae

Question 7

What is the name of the group of bacteria that are gram-positive rods often referred to as club-shaped or V & L forms when viewed in a Gram stain?

A) Corynebacterium
B) Staphylococcus
C) Neisseria
D) Listeria

Question 8

What organism is a member of the human oropharyngeal biota but has been isolated from people with endocarditis?

A) Listeria monocytogenes
B) Rhodococcus equi
C) Rothia dentocariosa
D) Corynebacterium diphtheriae

Question 9

What Corynebacterium species is commonly associated with hospitalized immunocompromised patients?

A) C. pseudotuberculosis
B) C. jeikeium
C) C. striatum
D) C. ulcerans

Question 10

What organisms are described as partially acid fast and diphtheroid gram-positive rods with traces of branching on a Gram stain?

A) Rothia dentocariosa
B) Rhodococcus equi
C) Listeria monocytogenes
D) Erysipelothrix rhusiopathiae

Question 11

What organism displays Babès-Ernst granules on a Gram stain?

A) Listeria monocytogenes
B) Erysipelothrix rhusiopathiae
C) Rhodococcus equi
D) Corynebacterium diphtheriae

Question 12

All of the following species of Arcanobacterium are clinically significant, except

A) Arcanobacterium haemolyticum.
B) Trueperella pyogenes (previously A. pyogenes).
C) Trueperella bernardiae (previously A. bernardiae).
D) A. urealyticum.

Question 13

What test is performed to determine if Corynebacterium diphtheriae is a toxigenic strain of an organism?

A) Elek test
B) Schick test
C) Lancefield group test
D) Coagulase

Question 14

What is one of the most frequently isolated, clinically significant corynebacteria associated with UTIs?

A) Corynebacterium ulcerans
B) C. pseudotuberculosis
C) C. urealyticum
D) C. diphtheriae

Question 15

What is the name of the organism that, before being identified as an important cause of infections in immunocompromised patients, was considered a common laboratory contaminant?

A) Streptococcus pyogenes
B) Bacillus subtilis
C) Rhodococcus sp.
D) Arcanobacterium sp.

Question 16

Erysipelothrix rhusiopathiae produces all the following diseases, except

A) septicemia.
B) meningitis.
C) endocarditis.
D) erysipeloid.

Question 17

What organism is responsible for spontaneous abortion and stillborn neonates, and can cause meningitis with a fatality rate approaching 50% in newborns?

A) Corynebacterium diphtheriae
B) Rhodococcus equi
C) Rothia dentocariosa
D) Listeria monocytogenes

Question 18

What is the name of the Bacillus sp. that causes anthrax in cattle?

A) B. anthracis
B) B. cereus
C) B. asteroids
D) B. subtilis

Question 19

A young girl is brought to her physician by her mother, who says the child has been very sluggish with a fever of 38° C (100.5° F) for a week. The mother noticed that the child's tonsils were red and that the previous day the back of her throat turned a gray color and looked to have a gray membrane on it. What disease should the physician suspect?

A) Strep throat
B) Tonsillitis
C) Diphtheria
D) Scarlet fever

Question 20

What is the name of the bacterium that plays an important role in the health of the female vaginal tract, protecting it against pathogens?

A) Corynebacterium
B) Gardnerella vaginalis
C) Erysipelothrix rhusiopathiae
D) Lactobacillus

Question 21

What is the name of the iron-chelating compound produced by Nocardia spp.?

A) Nocobactin
B) Novobiocin
C) Narcalase
D) Niacin

Question 22

All the following tests should be performed by sentinel laboratories to rule out the possibility of Bacillus anthracis from an isolate, except

A) gram stain.
B) glucose fermentation.
C) catalase.
D) motility.

Question 23

What bacterium produces colonies that are nonhemolytic, large, gray, and flat with an irregular margin on SBA?

A) Bacillus anthracis
B) Streptococcus pneumoniae
C) Nocardia asteroides
D) Listeria monocytogenes

Question 24

What form of anthrax is found among animal workers and has been called Woolsorter disease?

A) Cutaneous
B) Gastrointestinal
C) Inhalation
D) Optical

Question 25

What bacteria's morphology is described as large, square-ended, gram-positive or gram-variable rods found singly or in chains?

A) Streptococcus pneumoniae
B) Nocardia asteroids
C) Listeria monocytogenes
D) Bacillus anthracis

Question 26

What Bacillus sp. is a relatively common cause of food poisoning and opportunistic infection in susceptible hosts?

A) Bacillus cereus
B) B. anthracis
C) B. asteroids
D) B. pneumoniae

Question 27

Which of the following would be considered a diphtheroid?

A) Corynebacterium sp.
B) Nocardia sp.
C) Erysipelotghrix rhusiopathiae
D) Listeria monocytogenes

Question 28

Why is it important to differentiate infections with Nocardia spp. in pulmonary infections?

A) Antifungal agents do not kill these organisms.
B) These organisms are resistant to penicillin.
C) These organisms are susceptible to sulfonamides.
D) All of the above.

Question 29

Why is it that although Nocardia spp. grow on most common nonselective laboratory media, many are missed when the cultures are read?

A) These organisms require 3 to 6 days to grow.
B) These organisms require factors X and V to grow.
C) These organisms require 3 to 6 weeks to grow.
D) These organisms are anaerobic.

Question 30

All of the following are commonly encountered Nocardia spp., except

A) Nocardia asteroides.
B) N. brasiliensis.
C) N. transvalensis.
D) N. nova.

Question 31

How can Nocardia spp. be presumptively identified?

A) Strong staining with Gram stain and the presence of filamentous, branching organisms
B) Medusa head colonies with filamentous, branching organisms present on acid-fast stain
C) Sulfur granules that when crushed and Gram stained reveal filamentous, branching organisms
D) Filamentous, branching organisms with a carbolfuchsin acid-fast stain with a weak acid decolorizer, but not a Kinyoun acid-fast stain

Question 32

What other gram-positive rod is similar to Bacillus anthracis morphologically and metabolically?

A) B. subtilis
B) B. cereus
C) L. monocytogenes
D) E. rhusiopathiae

Question 33

The presence of gram-variable bacilli on the surface of epithelial cells collected from the vaginal mucosa indicates

A) cervicitis.
B) bacterial vaginosis.
C) diphtheria.
D) poor staining technique.

Question 34

Which of the following is true about Nocardia spp.?

A) These organisms grow on standard nonselective media.
B) Growth may take a week or more.
C) Infections occur in immunocompromised patients.
D) All of the above.

Question 35

What are the confirmatory tests performed at a state laboratory for Bacillus anthracis?

A) Flagellar antigen and mannitol fermentation
B) Endospore stain and a capsule antigen
C) Cell wall polysaccharide and a capsule antigen
D) Cell wall polysaccharide and an endospore stain

Question 36

The three proteins that make up the anthrax toxin include all the following, except

A) protective antigen.
B) edema factor.
C) cellular factor.
D) lethal factor.

Question 37

What disease is considered a complication of any form of anthrax (cutaneous, gastrointestinal, or inhalation)?

A) Sepsis
B) Endocarditis
C) Meningitis
D) Gangrene

Question 38

What is the name of the Nocardia sp. that most frequently causes a cutaneous infection?

A) Nocardia nova
B) N. brasiliensis
C) N. asteroides
D) N. transvalensis

Question 39

What antibiotic, in 2000, was approved by the U.S. Food and Drug Administration (FDA) for postexposure inhalation anthrax?

A) Penicillin
B) Erythromycin
C) Cephalosporin
D) Ciprofloxacin

Question 40

How is anthrax spread in animals?

A) Respiratory droplet where the bacteria are directly transferred
B) Intimate contact where the bacteria are directly transferred
C) Drinking contaminated water where the bacteria are directly transferred
D) Eating plants contaminated with the spores

Question 41

Colonies of Bacillus anthracis are described as

A) Curschmann's spiral.
B) Mickey Mouse ears.
C) Medusa's heads.
D) flower like.

Question 42

What is the name of the genus whose members are called nocardioforms?

A) Gordonia
B) Weimeronia
C) Rhodococcus
D) Tsukamurella

Question 43

The colonies of this organism form large, rough, greenish, hemolytic colonies on blood agar. What organism is it?

A) Staphylococcus aureus
B) Escherichia coli
C) Streptococcus pyogenes
D) Bacillus cereus

Question 44

What is the name of the genus of organisms that are primarily saprophytic and resemble aerobic actinomycetes with the morphology and diseases they cause?

A) Actinomadura
B) Saprophytes
C) Streptomyces
D) Streptococcus