Deck 14: Bacillus and Similar Organisms

Question 1

Induction of capsule formation by B.anthracis can be accomplished with _____ agar.

A)5% sheep blood
B)PLET acetate
C)bicarbonate
D)urea

Answer 1

C
As a means of identification,bicarbonate agar is used to induce B.anthracis capsule formation.

Question 2

Which of the following types of anthrax occurs after ingesting the spores and affects the abdominal or oropharyngeal area? (Patients usually die from toxemia and overwhelming sepsis. )

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

Answer 2

C
Gastrointestinal anthrax can be fatal as a result of toxemia and an overwhelming sepsis that cannot be controlled.

Question 3

Media that can be used for isolating Bacillus anthracis include:

A)Thayer-Martin agar.
B)5% sheep blood agar.
C)MacConkey agar.
D)Columbia blood agar with colistin-nalidixic acid (CNA).

Answer 3

B
All Bacilli and related genera grow well on 5% sheep blood agar,chocolate agar,routine blood culture media,and commonly used nutrient broths.They will not grow on MacConkey agar,and those that are susceptible to nalidixic acid will not grow on Columbia blood agar with CNA.Two special media are used for the isolation and identification of B.anthracis.Polymyxin-lysozyme-ethylenediaminetetraacetic-thallous (PLET)acetate can be used for the selection and isolation of this species from contaminated specimens.As a means of identification,bicarbonate agar is used to induce B.anthracis capsule formation.

Question 4

Suspect spore-forming,gram-positive Bacillus species that is g-hemolytic,nonmotile,and penicillin-susceptible and that produces a wide zone of lecithinase on egg yolk agar can be identified as:

A)Corynebacterium diphtheria.
B)B.anthracis.
C)Bacillus cereus.
D)Corynebacterium jeikeium.

Question 5

The microbiologist identified an organism that produces large g-hemolytic colonies on blood agar and appears as a gram-variable rod on Gram staining.In order to further identify the organism,the microbiologist should:

A)no further identification is necessary.
B)complete a biochemical panel and antibiotic sensitivity.
C)complete a biochemical panel,no antibiotic sensitivity is warranted.
D)report the organism as Bacillus spp.

Question 6

Induction of sporulation by Bacillus species can be accomplished with _____ agar.

A)5% sheep blood
B)PLET acetate
C)bicarbonate
D)urea

Question 7

Enzyme-linked immunosorbent assays (ELISAs)are available that can serologically identify which Bacillus species?

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

Question 8

A patient diagnosed with B.anthracis is allergic to penicillin.Which antibiotic can be given that will be therapeutically effective?

A)Ampicillin
B)Ciprofloxacin
C)Imipenem
D)Vancomycin

Question 9

Which of the following is described as a spore-forming,gram-positive Bacillus that is b-hemolytic,motile,Voges-Proskauer (VP)-positive,and citrate-positive and causes two types of food poisoning as a result of toxin release?

A)C.diphtheria
B)B.anthracis
C)B.cereus
D)C.jeikeium

Question 10

A U.S.Food and Drug Administration (FDA)-cleared immunochromatographic test produces a red line on the cassette and can presumptively identify which gram-positive Bacillus that is g-hemolytic and morphologically has a "Medusa head" appearance when grown on 5% sheep blood agar?

A)Bacillus subtilis
B)B.cereus
C)B.mycoides
D)B.anthracis

Question 11

A gram-positive Bacillus,which is b-hemolytic on 5% sheep blood agar,produces a wide zone of lecithinase on egg yolk agar,is nonmotile,and was isolated from the stool of a patient with abdominal pain and watery diarrhea.Because of the patient's existing immunocompromised state,the physician administered penicillin as the antibiotic therapy.The patient's condition did not improve after 7 days of treatment.Which one of the following statements explains the reason for the antibiotic failure?

A)The course was too abbreviated and should be given for 14 days.
B)The patient may be allergic to penicillin and its therapeutic effects.
C)Penicillin is ineffective against gram-positive organisms.
D)The organism produces b-lactamase,which renders the drug inactive.