Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is an aerobic, nonfermentative, Gram-negative bacterium. It is an uncommon bacterium and human infection is difficult to treat. Initially classified as Bacterium bookeri, then renamed Pseudomonas maltophilia, S. maltophilia was also grouped in the genus Xanthomonas before eventually becoming the type species of the genus Stenotrophomonas in 1993.

S. maltophilia is slightly smaller (0.7–1.8 × 0.4–0.7 μm) than other members of the genus. They are motile due to polar flagella, and grow well on MacConkey agar producing pigmented colonies. S. maltophilia is catalase-positive, oxidase-negative (which distinguishes it from most other members of the genus) and has a positive reaction for extracellular DNase.

S. maltophilia is ubiquitous in aqueous environments, soil, and plants; it has also been used in biotechnology applications. In immunocompromised patients, S. maltophilia can lead to nosocomial infections. It is also an emerging nosocomial pathogen associated with opportunistic infections in patients with cystic fibrosis, cancer, and HIV/AIDS. Adherence of this organism to abiotic surfaces such as medical implants and catheters represents a major risk for hospitalized patients.