Rate of Transmission of Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae Without Contact Isolation

Background. Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are emerging worldwide. Contact isolation is recommended; however, little is known about the rate of transmission without contact isolation in the non-epidemic setting. Therefore, we aimed to estimate the rate of spread (R-0) of ESBL-producing Enterobacteriaceae in a tertiary care center with 5 intensive care units. Methods. In this observational cohort study performed from June 1999 through April 2011, all patients at the University Hospital Basel, Switzerland, who were hospitalized in the same room as a patient colonized or infected with an ESBL-producing Enterobacteriaceae for at least 24 hours (index case) were screened for ESBL carriage by testing of rectal swab samples, swab samples from open wounds or drainages, and urine samples from patients with foley catheters. Strains with phenotypic evidence for ESBL were confirmed by polymerase chain reaction. Nosocomial transmission was assumed when the result of screening for ESBL carriage in a contact patient was positive and molecular typing by pulsed-field gel electrophoresis (PFGE) revealed clonal relatedness with the strain from the index patient. Results. Active screening for ESBL carriage could be performed in 133 consecutive contact patients. Transmission confirmed by PFGE occurred in 2 (1.5%) of 133 contact patients, after a mean exposure to the index case of 4.3 days. Conclusions. The estimated rate of spread of ESBL-producing Enterobacteriaceae-in particular, Escherichia coli-was low in a tertiary care university-affiliated hospital with high levels of standard hygiene precautions. The low level of nosocomial transmission and the rapid emergence of community-acquired ESBL challenge the routine use of contact isolation in a non-epidemic setting, saving resources and potentially improving patient care.