Use of the quantitative antibiogram method for assessing nosocomial transmission of ESBL-producing Enterobacteriaceae in a French hospital.

BACKGROUND: ESBL-producing Enterobacteriaceae (eESBL) have a high prevalence in hospitals but real-time monitoring of nosocomial acquisition through conventional typing methods is challenging. Moreover, patient-to-patient transmission varies between the main species, namely Escherichia coli, and Klebsiella pneumoniae, then questioning the relevance of applying identical preventive measures.

AIM: To detect eESBL cross-transmission events (CTE) using combination of quantitative antibiogram with epidemiological data (combined-QA), and to rule on the effectiveness of standard or contact precautions for eESBL species.

METHODS: First, a validation set was used to confirm the relevance of the combined-QA by comparison to a combination of pulsed-field gel electrophoresis and epidemiological data (combined-PFGE). Secondly, a four-year retrospective analysis was conducted to detect eESBL-CTE in hospitalized patients. Two species were screened i.e. ESBL-E. coli (ESBL-Ec), and ESBL-K. pneumoniae (ESBL-Kp). During the study, only standard precautions were applied to ESBL-Ec patients whereas contact precautions were retained for ESBL-Kp.

FINDINGS: As a proof of concept, results between the two combined methods for the detection of CTE were identical for E. coli, and similar to at least 75% for K. pneumoniae. During the retrospective analysis, 722 patients with ESBL-Ec isolates and 280 with ESBL-Kp isolates were included. Nine CTE were identified for E. coli and 23 for K. pneumoniae, implying 20 (2.7%) and 36 (12.8%) patients, respectively.

CONCLUSION: The QA-combined method constitutes a rapid tool for epidemiological surveillance to detect CTE. In our hospital, standard precautions are sufficient to prevent acquisition of ESBL-Ec whereas contact precautions must be implemented to prevent acquisition of ESBL-Kp.