Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is an aerobic, gram-negative bacterium with generally lower virulence, the rare but difficult to treat infections in humans may cause. Originally, the bacterium was classified as Pseudomonas maltophilia and been attributed to the genus Xanthomonas. Only in 1993 it was classified as a separate species to the Stenotrophomonaden.

S. maltophilia is slightly smaller ( 0.7-1.8 × 0.4-0.7 microns ) than other Stenotrophomonaden. It is flagellated and grows well on MacConkey agar in colored colonies. S. maltophilia is catalase, oxidase negative (in contrast to most other members of the main group ) and secretes an extracellular DNase.

S. maltophilia is ubiquitous in aqueous environments, soil and plants, and may be in the urine and the secretions of the respiratory tract find. It may in particular cause nosocomial infections in immunodeficiency. The bacterium is also used for biotechnological applications.

Clinical Significance

S. maltophilia is often identified as a contaminant, such as to food and in a humidifier, but also in hemodialysis, infusion solutions for parenteral nutrition, and antiseptic solutions, such as chlorhexidine or quaternary ammonium compounds. The germ also often shows itself in biofilms; S. maltophilia may be found in intubated or tracheostomized patients on the tube, in catheterized patients the bladder catheter and in patients with implanted cardiac pacemakers. Growth detection in sputum or urine is not clearly interpretable in some cases and may be regarded as evidence of a relevant infection if he is from a normally bacteria-free medium such as blood or puncture urine.

In immunocompetent patients S. maltophilia does not lead to pneumonia, urinary tract infection or bacteremia in the rule. In immunocompromised patients, the bacterium may well cause respiratory infections. There is evidence of an increase in S. maltophilia colonization in cystic fibrosis patients in whom S. maltophilia can also cause chronic infections of the lower respiratory tract.

S. maltophilia is inherently resistant to many antibiotics, often speaks but on co-trimoxazole and tigecycline, but the number of resistant strains is also increasing.