Molecular investigation of Stenotrophomonas maltophilia isolates exhibiting rapid emergence of ticarcillin-clavulanate resistance.

The prevalence of Stenotrophomonas maltophilia resistance to ticarcillin-clavulanate has dramatically increased in our hospital over the past few years. Sixty-six clinical isolates, collected from 61 patients, were tested for antibiotic susceptibility and genotyped by two different enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) systems. Although two small outbreaks were identified in the medical intensive care unit, the remaining 58 strains generated 48 different PCR patterns. The rapid emergence of resistance in S. maltophilia occured in absence of an epidemic and was probably influenced by increasing-b-lactam use in our hospital.