Ther are limited antimicrobial options for infections due to S. maltophilia because of its extensive resistance to most antibiotics, including β-lactam antibiotics, cephalosporins, macrolides, aminoglycosides, and carbapenems (naturally resistant to imipenem, meropenem and ertapenem). Interpretive breakpoints for susceptibility are available only for ticarcillin/clavulanate, ceftazidime, minocycline, levofloxacin, trimethoprim/sulfamethoxazole (TMP/SMX) and chloramphenicol (CLSI, 2015).
TMP/SMX is recognized as the drug of choice (Wang et al., 2014a). Resistance rates vary geographically but are generally less than 10% (Chung et al., 2013).
Ceftazidime and ticarcillin/clavulanate used to be the most effective among β-lactam drugs against S. maltophilia. However, recent studies have demonstrated resistance rates of more than 30 % and a trend in decreasing susceptibility with ceftazidime. The same is true for ticarcillin/clavulanate.
New fluoroquinolones exhibit better ponency against S. maltophilia than ceftazidime or ticarcillin/clavulanate and have become reasonable alternatives (see here)
Abbreviations: MEM meropenem (carbapenems), IPM imipenem (carbapenems), ETP ertapenem (carbapenems), AKN amikacin (aminoglycosides), PTZ piperacillin/tazobactam (penicillins), TGC tigecycline
Update on infections caused by Stenotrophomonas maltophilia with particular attention to resistance mechanisms and therapeutic options. Ya-Ting Chang, Chun-Yu Lin, Yen-Hsu Chen and Po-Ren Hsueh. Frontiers in Microbiology. 2015.
Wang et al., 2014a. Comparisions between patients with trimethoprim-sulfamethoxazole-susceptible and trimethoprim-sulfamethoxazole-resistant Stenotrophomonas maltophilia monomicrobial bacteremia: A 10-year retrospective study. J. Microbiol. Immunol. Infect. doi: 10.1016/j.jmii.2014.06.005.
Chung et al., 2013. Antimicrobial susceptibility of Stenotrophomonas maltophilia isolates from Korea, and the activity of antimicrobial combinations against the isolates. J. Korean Med.Sci. 28, 62-66. doi: 10.3346/jkms.2013.28.1.62.