Deck 16: Aerobic Gram-Positive Bacilli

Question 1

Several people from a picnic came down with a gastrointestinal disturbance,and public health officials suspected a case of food poisoning.The food,especially hot dogs,were cultured and after 24 hours of growth on sheep blood agar (SBA),there was a small,round,smooth,translucent colony surrounded by a narrow zone of b-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

Answer 1

A
L.monocytogenes is catalase positive and motile at room temperature,which along with b-hemolysis excludes corynebacteria.In wet mount preparations,L.monocytogenes exhibits "tumbling motility" when viewed microscopically.In motility medium,the characteristic "umbrella" pattern is seen when the organism is incubated at room temperature.

Question 2

All of the following species of Arcanobacterium are clinically significant EXCEPT:

A) Arcanobacterium haemolyticum
B) A. pyogenes
C) A. bernardiae
D) A. urealyticum

Answer 2

D
Three species of Arcanobacterium are clinically significant: A.haemolyticum,A.pyogenes,and A.bernardiae.

Question 3

What is the major virulence factor associated with Corynebacterium diphtheriae?

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

Answer 3

B
The major virulence factor associated with C.diphtheriae is the diphtheria toxin.This toxin is produced by strains of C.diphtheriae infected with a temperate bacteriophage,which carries the tox gene for diphtheria toxin.Only toxin-producing strains cause the disease diphtheria.

Question 4

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

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

Question 5

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

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

Question 6

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

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

Question 7

All the following are general characteristics of the genus Bacillus EXCEPT:

A) Aerobic
B) Gram positive
C) Form endospores
D) Cocci

Question 8

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 yesterday 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 9

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

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

Question 10

What organism shows diphtheroid gram-positive rods with traces of branching on a Gram stain?

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

Question 11

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 12

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 two weeks,so the foreman sends him to the doctor.The doctor takes scrapings from the sores and sends them to the laboratory for a culture and sensitivity.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 13

What is one of the most frequently isolated,clinical significant corynebacteria?

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

Question 14

After 24 hours,a sheep blood agar (SBA)from a vaginal culture is read.The SBA has a-hemolytic,pinpoint,rough colonies all over the plate.A catalase test is performed,and it is negative.What organisms do these characteristics fit?

A) Lactobacillus and viridans streptococci
B) Diphtheroids and rhodococci
C) Staphylococcus and Listeria
D) Corynebacterium and Arcanobacterium

Question 15

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

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

Question 16

What is the name of the group of bacteria that are slightly curved,gram-positive rods often referred to as club-shaped or Chinese letters when viewed in a Gram stain?

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

Question 17

Erysipelothrix rhusiopathiae produces all the following diseases EXCEPT:

A) Septicemia
B) Meningitis
C) Endocarditis
D) Erysipeloid

Question 18

What Corynebacterium infects mostly immunocompromised patients?

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

Question 19

What is the colony morphology of A.haemolyticum on sheep blood agar (SBA)?

A) A narrow zone of b-hemolysis and a black opaque dot is seen when the colony is scraped away.
B) Gamma 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.

Question 20

What media does Corynebacterium diphtheriae grow on?

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

Question 21

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 22

What is the name of the Nocardia sp.that causes a chronic confluent bronchopneumonia?

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

Question 23

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 24

What form of anthrax is found among animal workers and has been dubbed woolsorter's disease?

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

Question 25

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

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

Question 26

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 27

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 28

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

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

Question 29

What is the name of the species that,before the onset of bioterrorism and immunocompromised patients,was considered a common laboratory contaminant?

A) Streptococcus
B) Bacillus
C) Rhodococcus
D) Arcanobacterium

Question 30

What antibiotic,in 2000,was approved by the Food and Drug Administration (FDA)for post exposure inhalation anthrax?

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

Question 31

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 32

Which of the following is true about Nocardia spp.?

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

Question 33

What bacterium produces colonies that are nonhemolytic,large,gray,and flat with an irregular margin on sheep blood agar (SBA)?

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

Question 34

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

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

Question 35

The symptoms of gastrointestinal anthrax include all the following EXCEPT:

A) Abdominal pain
B) Rice water stools
C) Bloody diarrhea
D) Vomiting

Question 36

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 asteroides
C) Listeria monocytogenes
D) Bacillus anthracis

Question 37

How is anthrax spread in animals?

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

Question 38

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 39

All of the following are commonly encountered Nocardia spp.EXCEPT:

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

Question 40

The symptoms of inhalation anthrax include all of the following EXCEPT:

A) Productive cough
B) Dyspnea
C) Cyanosis
D) Disorientation

Question 41

What are the names of the species of organism that are primarily saprophytic organisms and resemble other aerobic actinomycetes with the morphology and diseases they cause?

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

Question 42

Why is it that although Nocardia spp.grow well 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 43

Why is it extremely important to diagnose infections with Nocardia spp.?

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 44

Infections caused by Tsukamurella paurometabola include all the following EXCEPT:

A) Chronic lung infection
B) Brain abscesses
C) Knee prosthesis infection
D) Conjunctivitis

Question 45

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

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