Stenotrophomonas maltophilia

Gram Stain

• Gram negative bacilli small straight - nonfermenter (aerobic)

Clinical Significance

This organism is found in a variety of environmental sources. It adheres to plastics to form biofilms.

It is often a colonizer of the respiratory tract in patients who have received broad spectrum antibiotics (especially carbapenems), have been mechanically ventilated, are neutropenic, or have cystic fibrosis.  Opportunistic infection may occur in these patient populations but it is important to differentiate colonization from infection.

S. maltophilia has been associated with bacteremia, meningitis, endocarditis, peritonitis, biliary sepsis, pneumonia, ocular infections (endophthalmitis, keratitis, scleritis, dacryocystitis), genitourinary, and skin/soft tissue infections.

Usual Susceptibility Pattern

This organism exhibits broad resistance to penicillins, cephalosporins, carbapenems, aminoglycosides, macrolides, and quinolones.

Although usually susceptible to TMP/SMX, resistance is increasing. It is susceptible to colistin and usually to doxycycline/minocycline. 

Resistance to multiple disinfectants has also been reported.

In serious infections, combination therapy may be beneficial.

Consultation with microbiologist is recommended for additional susceptibility testing.