OBJECTIVETo investigate the antibiotic resistance and risky factors of nosocomial infections caused by Stenotrophomonas maltophilia, so as to help elucidate the difference of drug resistance between metallic beta-lactamase (MBL) producing and non-MBL producing strains.

METHODSStandard agar dilution method of NCCLS was employed in the isolation of 36 strains of Stenotrophomonas maltophilia from patients with nosocomial infection with respect to their in vitro antibiotic resistance to 18 kinds of antibiotics. MBL strains were identified by MBL-E test method.

RESULTSStenotrophomonas maltophilia in our hospital was mainly identified in the lower respiratory tract (88.9%), in which 88.2% (30/34) of the patients had serious original diseases, 50% of whom had received Imipenem/cilastatin sodium treatment. Thirty-six strains of Stenotrophomonas maltophilia were susceptible to new types of fluoquinolone antibiotics, i.e. Sparfloxacin, levofloxacin, gatifloxacin and doxycycline, with inhibitory rate ranging 97.2%, 94.4%, 91.7% to 83.3%, respectively. They could also be inhibited by SMZ/TMP and Ticarcillin/Lavulanic acid with inhibitory rate of 63.9% and 58.3%, respectively. There were 16 strains out of 36 of MBL bacteria with complete resistance to Imipenem/cilastatin sodium, but with higher susceptibility to aztreonam than those non-MBL producing strains.

CONCLUSIONThe nosocomial infection in our hospital caused by Stenotrophomonas maltophilia seemed to be related with severe primary disease and the use of Imipenem/cilastatin sodium. The newly developed fluoroquinolones possessed powerful antibacterial potency on Stenotrophomonas maltophilia found in nosocomial infection.