Deck 20: Acinetobacter, Stenotrophomonas, and Other Organisms

Question 1

For more serious infections caused by Acinetobacter spp., such as pneumonia or bacteremia, effective treatment may require the use of

A)multiple rounds of penicillin or similar antibiotic.
B)a beta-lactam agent in combination with an aminoglycoside.
C)repeated high level doses of gentamycin.
D)single-drug therapy in combination with a steroid.

Answer 1

B
For urinary tract infections caused by Acinetobacter spp., single-drug therapy is usually sufficient. In contrast, more serious infections, such as pneumonia or bacteremia, may require the use of a beta-lactam agent in combination with an aminoglycoside.

Question 2

Of the following species, which are widely distributed in nature and hospital environments?

A)Pseudomonas luteola
B)Acinetobacter spp.
C)Pseudomonas oryzihabitans
D)Bordetella trematum

Answer 2

B
These organisms inhabit environmental niches, with Acinetobacter spp. and S. maltophilia being widely distributed in nature and hospital environments In contrast, Pseudomonas luteola, Pseudomonas oryzihabitans, and CDC group NO-1 are not commonly encountered in the clinical setting.

Question 3

The primary drug of choice for infections caused by S.maltophilia is

A)a beta-lactam agent in combination with an aminoglycoside.
B)trimethoprim-sulfamethoxazole.
C)ticarcillin/clavulanic acid.
D)chloramphenicol.

Answer 3

B
S. maltophilia is notoriously resistant to most currently available antimicrobial agents, leaving trimethoprim-sulfamethoxazole as the primary drug of choice for infections caused by this species. Although a few other agents, such as minocycline, ticarcillin/clavulanic acid, and chloramphenicol, often exhibit in vitro activity, clinical experience with these agents is not extensive. Therefore, trimethoprim-sulfamethoxazole remains the drug of choice.

Question 4

An organism that can be described as oxidase-negative, MacConkey agar-positive, glucose nonfermenter is likely

A)Escherichia.
B)Pseudomonas.
C)Acinetobacter.
D)Moraxella.

Question 5

Differentiation of S.maltophilia and Burkholderia cepacia is best accomplished by

A)the oxidase test.
B)maltose and glucose medium.
C)tyrosine-enriched heart infusion agar.
D)All of the above are correct.

Question 6

Plump coccobacilli that tend to resist alcohol decolorization and may be mistaken for Neisseria spp.are

A)Bordetella spp.
B)S.maltophilia.
C)Acinetobacter spp.
D)P.oryzihabitans.

Question 7

The natural habitat of Acinetobacter sp.can best be described as

A)the mucous membranes of animals.
B)the gastrointestinal tract of humans and other animals.
C)the natural environment.
D)the genitourinary tract of animals.