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Chapter 16. Pseudomonas, Acinetobacter, Burkholderia, and Stenotrophomonas

A sputum culture of a patient with cystic fibrosis grows P. aeruginosa that forms very mucoid colonies. The implication of this observation is which one of the following?

(A) The P. aeruginosa is highly susceptible to the aminoglycoside antimicrobial tobramycin.

(B) The P. aeruginosa is infected with a pyocin (a bacteriocin).

(C) The colonies are mucoid because they have polysaccharide capsule of hyaluronic acid.

(D) The exotoxin A gene has been disabled and the P. aeruginosa is no longer able to block host cell protein synthesis.

(E) The P. aeruginosa has formed a biofilm in the patient’s airway.

An environmental Gram-negative bacillus that is resistant to cephalosporins, aminoglycosides, and quinolones has become a very important nosocomial pathogen largely because it is selected by use of those antibiotics. This Gram-negative bacillus can take 2–3 days to grow and must be differentiated from B. cepacia. It is

(A) P. aeruginosa

(B) A. baumannii

(C) Alcaligenes xylosoxidans

(D) Klebsiella pneumoniae

(E) S. maltophilia

A 17-year-old girl with cystic fibrosis has a slight increase in her frequent cough and production of mucoid sputum. A sputum specimen is obtained and plated on routine culture media. The predominant growths are Gram-negative bacilli that form very mucoid colonies after 48 hours of incubation. These bacilli are oxidase positive, grow at 42°C, and have a grapelike odor. These Gram-negative bacilli are which of the following?

(A) K. pneumoniae

(B) P. aeruginosa

(C) Staphylococcus aureus

(D) Streptococcus pneumoniae

(E) B. cepacia

The sputum from a 26-year-old patient with cystic fibrosis is plated on a colistin-containing agar. After 72 hours of incubation, the colistin-containing agar grows Gram-negative bacilli that are oxidase positive but are otherwise difficult to identify. This microorganism is of major concern. It is sent to a reference laboratory so that molecular methods can be used to identify or rule out which of the following?

(A) P. aeruginosa

(B) B. cepacia

(C) Haemophilus influenzae

(D) Pseudomonas putida


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