Abstract
BackgroundStenotrophomonas maltophilia is an important opportunistic, mainly nosocomial pathogen that emerged in the last decades worldwide. Due to its inherent extended antibiotic resistance, therapeutic options are strongly limited. New resistance mechanisms in S. maltophilia make antibiotic therapy even more difficult. The aim of our study was to investigate the antimicrobial resistance of S. maltophilia isolates collected in our laboratory and to reveal related clinical background.MethodConsecutive non-duplicate S. maltophilia isolates (n = 160) were collected in a three-year period. Conventional methods, automated identification system and MALDI-TOF MS was used for identification, ERIC-PCR for genetic relationship analysis and broth microdilution method to determine the susceptibility for trimethoprim/sulfamethoxazole (SXT), ciprofloxacin, levofloxacin, moxifloxacin, colistin, doxycycline and tigecycline. Clinical final reports were used retrospectively to collect clinical information.ResultsERIC-PCR revealed large heterogeneity. Trimethoprim/sulfamethoxazole, moxifloxacin and levofloxacin were found to be the most effective agents with MIC50/MIC90 0.5/1, 0.25/1, 1/2 mg/l, respectively. Seventy percent of patients with S. maltophilia infection were treated in intensive care units. All-cause mortality rate was 45%. Nearly 70% of the isolates were collected from polymicrobial infections/colonizations.ConclusionsTrimethoprim/sulfamethoxazole is the most potent antibiotic agent against S. maltophilia. In case of SXT hypersensitivity, intolerance or resistance, fluoroquinolones are alternative therapeutic options. Missing clinical breakpoints, consensus antibiotic susceptibility testing guidelines and clinical trials make the interpretation of antibiotic susceptibility testing results difficult. The indirect pathogenicity of S. maltophilia in polymicrobial infections or colonizations has to be taken into consideration.
Highlights
Stenotrophomonas maltophilia is an important opportunistic, mainly nosocomial pathogen that emerged in the last decades worldwide
Consensus antibiotic susceptibility testing guidelines and clinical trials make the interpretation of antibiotic susceptibility testing results difficult
The indirect pathogenicity of S. maltophilia in polymicrobial infections or colonizations has to be taken into consideration
Summary
Stenotrophomonas maltophilia is an important opportunistic, mainly nosocomial pathogen that emerged in the last decades worldwide. The aim of our study was to investigate the antimicrobial resistance of S. maltophilia isolates collected in our laboratory and to reveal related clinical background. Stenotrophomonas maltophilia has emerged as an important opportunistic and nosocomial pathogen in recent years worldwide [1,2]. The emergence of new resistance mechanisms in S. maltophilia requires substantial monitoring and reporting of antibiotic suspectibility of clinical isolates [5]. The aim of our study was to investigate the antimicrobial resistance of S. maltophilia isolates collected in Diagnostic Laboratory of Clinical Microbiology, Institute of Laboratory Medicine, Semmelweis University (Budapest, Hungary) and to reveal whether isolates were infective or colonizers, the type of infections, the predisposing factors of infected patients, antibiotic therapy and the outcome of infections
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