Pathogens
Stenotrophomonas maltophilia

Stenotrophomonas maltophilia

Precautions

Standard Precautions

General Information

Culture.

Aerobic, non-fermentative, Gram-negative bacillus (formerly Xanthomonas or Pseudomonas maltophilia). 

It is an uncommon opportunistic pathogen but when encountered, can be problematic because of multi-drug resistance. 

Infections are most often in highly compromised individuals and/or associated with invasive devices (e.g. IV catheters). Surgical site infection clusters can be found when surgical preparation materials (e.g. biocides, soaked sponges) are contaminated with disinfectant resistant strains. As an environmental organism, it can also be found incidentally on external surfaces.

S. maltophilia is an environmental organism that can be found in water and soil. As an environmental organism that can also be resistance to biocides and disinfectants, hospital-associated infections (sporadic infections and clusters) can occur. 

Identification of a single S. maltophilia infection in a recently hospitalized patient should raise concerns about hospital-acquired infection. Identification of multiple cases should lead to investigation of a hospital-associated outbreak and the potential for the presence of contaminated supplies (e.g. prep solutions) or environments.

Main treatment options:

  • Trimethoprim-sulfonamide is the drug of choice in most situations. Resistance is very rare
  • Doxycycline and minocycline susceptibility is also common. Doxycycline has been shown to be similarly effective compared to TMS in humans
  • Ceftazidime or ticarcillin/clavulanic acid may be effective, but data are limited

Commonly or intrinsically resistant to:

  • Most beta-lactams (penicillins, cephalosporins and carbapenems); however, ceftazidime or ticarcillin/clavulanic acid might be effective
  • Aminoglycosides
  • Macrolides
  • Fluoroquinolones

Biocide resistance can also be encountered.