Molecular epidemiology of Stenotrophomonas maltophilia in a university hospital

The aim of this investigation was to study the molecular epidemiology of Stenotrophomonas maltophilia in a university hospital in Italy. Sixty-one clinical isolates were collected from 43 patients during a two-year period. The majority of specimens were from the respiratory tract (41 of 43) of patients in the adult intensive care unit (ICU) (19 of 43) or cystic fibrosis (CF) patients (13 of 43). Genotypic analysis by pulsed-field gel electrophoresis (PFGE) of clinical isolates identified 31 different PFGE patterns. Although most patients were infected or colonized by different S. maltophilia clones, clones with identical genotype were isolated in patients from ICU, where two separate outbreaks were identified. Antimicrobial susceptibility identified a multi-resistant phenotype in all S. maltophilia PFGE clones. The majority of PFGE clones identified (six of seven clones from patients in the ICU) were susceptible to fluoroquinolones. Mechanical ventilation was associated with S. maltophilia acquisition in the ICU.