Which of the following nonfermenters is rarely isolated in the United States?

• A. Pseudomonas aeruginosa
• B. Stenotrophomonas maltophilia
• C. Burkholderia mallei
• D. Burkholderia cepacia

Answer: (C)

Nonfermenters include several organisms commonly encountered in US labs, but one stands out for its extreme rarity here. Pseudomonas aeruginosa is a frequent cause of hospital-acquired infections, and Stenotrophomonas maltophilia often appears as an opportunistic pathogen in hospitalized patients. Burkholderia cepacia complex is also seen, especially in cystic fibrosis patients and healthcare settings. Burkholderia mallei, the agent of glanders, is historically linked to horses and remains extremely uncommon in the United States today due to strict animal health controls and surveillance. Because of these measures, isolation of Burkholderia mallei in the US is very rare, making it the correct choice.