ESBL-producing multidrug-resistant Providencia stuartii infections in a university hospital

To investigate the epidemiological and clinical findings of extended-spectrum beta-lactamase (ESBL)-producing Providencia stuartii infections in a large Italian university hospital.All consecutive episodes of P. stuartii infection that occurred during 1999-2002 were included in the study. For each patient, we recorded the area of hospitalization and drug susceptibility of the P. stuartii strains. Patients with ESBL-producing P. stuartii infection were considered cases and those with non-ESBL-producing P. stuartii infection were used as controls.One hundred and sixteen (52%) out of 223 P. stuartii strains collected during the study period were found to be ESBL-producing. On the basis of PCR and DNA sequencing experiments, TEM-52 was identified in 87% of isolates and TEM-72 in 13%. All ESBL-producing P. stuartii infections were nosocomially acquired. The prevalence increased from 31% of P. stuartii infections in 1999 to 62% in 2002 (P = 0.04). All 116 strains were classified as ESBL-producing multidrug-resistant P. stuartii, since 88% of the isolates were cross-resistant to ciprofloxacin and amikacin and the other 12% were cross-resistant to ciprofloxacin and gentamicin. At logistic regression analysis, advanced age (P0.001), previous hospitalization (P0.01), neoplastic disease (P0.001) and previous antibiotic therapy (P0.001) were independent risk factors for the development of ESBL-producing infections.This 4 year surveillance of Providencia complaints clearly indicates that infections caused by ESBL-producing multidrug-resistant P. stuartii are an emerging problem.