Antimicrobial resistance and epidemiology of extended spectrum-β-lactamases (ESBL)-producing Escherichia coli and Enterobacter cloacae isolates from intensive care units at obstetrics & gynaecology departments: a retrospective analysis

Background: There are increasing concerns towards the transmission of extended spectrum-β-lactamases (ESBL)-producing Enterobacteriaceae in hospital intensive care units (ICUs) at obstetrics & gynaecology departments. The aim of this study was to determine the clinical characteristics and prevalence of ESBL-producing Escherichia coli (E. coli) and Enterobacter cloacae (E. cloacae) isolates collected from ICUs at obstetrics & gynaecology departments in a tertiary care hospital, China. This study also explored the treatment options for E. coli and E. cloacae infections. Methods: E. coli and E. cloacae isolates from ICU samples were identified by using the Vitek 2 Compact System with the GN and ASTGN13 cards. Antimicrobial susceptibility profiles were determined by using the broth microdilution method. Double-disk synergy test (DDST) was performed to screen for ESBLs and combined with the EDTA-disc synergy to detect the production of carbapenemase. Enterobacterial repetitive intergenic consensus (ERIC)-PCR was applied to investigate the clonality of the isolates. Results: A total of 223 strains isolated from 283 hospitalized patients in the ICU with nosocomial infections between 2017 and 2019 were analyzed. Of these, 104 isolates were classified as E. coli and 103 isolates as E. cloacae by the VITEK GNI system. Of the 207 isolates, 131 (63.3%) were separated from sputum or tracheal secretions. ESBL-screen positive was 45.2% (47/104) for E. coli, and 44.7% (46/103) for E. cloacae. Resistance rates of ESBL-producing E. coli and E. cloacae isolates were 95.5% and 91.3% for ampicillin, respectively; 80.6% and 76.1% for ampicillin/tazobactam; 88.1% and 28.3% for ciprofloxacin; 89.6% and 15.2% for levofloxacin; 34.3% and 45.7% for netilmicin; 82.1% and 41.3% for compound sulfamethoxazole; 20.9% and 43.5% for amikacin; 58.2% and 37.0% for gentamicin; 20.9% and 69.6% for piperacillin/tazobactam. Additionally, all ESBL-producing isolates were fully resistant to cefazolin, cefuroxime, ceftazidime, ceftriaxone, cefepime, and aztreonam. On the other hand, isolates were fully susceptible to imipenem and meropenem. Results of ERIC-PCR in all of ESBL-producing E. coli isolates exhibited 11 distinct patterns with a similarity coefficient of 0.8. Only one distinct ERIC pattern was observed amongst the 46 strains of ESBL-producing E. cloacae. Analysis of ERIC patterns demonstrated that there was an outbreak of nosocomial infection of ESBL-producing E. coli and E. cloacae in obstetrics & gynecology ICU of this hospital. Discussion: Our data indicate that the ESBL-producing E. coli and E. cloacae are circulating in the ICU and constitute a major source infection spread. It is necessary to increase surveillance of infections in the ICU and develop adequate infection prevention strategies.