For a person with an infection of stenotrophomonas maltophilia in the
eyelid or bloodstream, is there any appropriate course of medical
treatment other than taking chloramphenicol?    Can chloramphenicol
still be bacteriostatic against a strain of S. maltophilia that has
become resistant to it?

Would trimethoprim and sulfamethoxazole combined be able to fight S.
maltophilia or inhibit the bacteria?

Hello rosemary25,
Thanks for requesting me to answer this question.

Is there any appropriate course of medical treatment other than taking 
chloramphenicol?

Stenotrophomonas maltophilia has been implicated as the causative 
agent of a variety of infections, including bacteremia, pneumonia, 
urinary tract infection, and soft tissue infection.  I will discuss 
the treatment of this bacteria.  If you require more information (i.e. 
epidemiology and clinical characteristics) I will be happy to research 
that in a separate question.

Antibiotic therapy of S. maltophilia infections is difficult for 
several reasons. The bacterium is intrinsically resistant to many 
broad-spectrum antibiotics commonly used to empirically treat 
suspected serious infections. An important characteristic of S. 
maltophilia is its resistance to different antibiotic classes mediated 
by several mechanisms, including the production of beta-lactamases.  S.
 maltophilia is typically resistant tocarbapenems and broad-spectrum 
cephalosporins, with the possible exception of ceftazidime. 
Aminoglycoside resistance is generally due to reduced antibiotic 
uptake. Rapid development of resistance to fluoroquinolones while the 
patient is receiving therapy also has been documented.

Additionally, in vitro antimicrobial susceptibility testing of S. 
maltophilia has several limitations. Antibiotics with in vitro 
activity include trimethoprim/sulfamethoxazone (TMP/SMX), ticarcillin/
clavulanate (not piperacillin/tazobactam), doxycycline, minocycline, 
and chloramphenicol. However, studies have shown that the results of 
in vitro testing may be affected by various factors, including the 
time of incubation and medium composition. Also, poor reproducibility 
among different testing methods has been described. There are no 
controlled clinical studies to determine the most effective antibiotic 
regimen, or the appropriate length of therapy. Antibiotic 
susceptibility studies and clinical observation suggest that the most 
active antibiotics against S. maltophilia are TMP-SMX and ticarcillin/
clavulanate.

Would trimethoprim and sulfamethoxazole combined be able to fight S. 
maltophilia or inhibit the bacteria?

Satler (2000) showed no correlation between the use of mono or dual 
antibiotic therapy and outcome. However, the high frequency of 
resistance and the possibility of development of resistance on therapy 
make dual antibiotic therapy reasonable for severe bloodstream 
infections.

In general, if an organism has become resistant to an antibiotic, 
there is no reason to continue the antibiotic.  Resistance would be an 
indication for therapeutic change.

Please use the answer clarification to ask any questions before rating
this answer.  I will be happy to explain any issue.

Thanks,
Kevin, M.D.

Search strategy:
No internet search engine was used in this answer.  All sources are
from objective, physician-written, peer-reviewed resources.

Medline search strategy:
“Stenotrophomonas maltophilia” restricted to English, full-text, 
review articles.

Bibliography:
Satler, CA. Stenotrophomonas maltophilia infection in children.  The 
Pediatric Infectious Disease Journal: 19 (9), 2000.