Extended-Spectrum-β-Lactamase-Producing Escherichia coli as a Cause of Pediatric Infections: Report of a Neonatal Intensive Care Unit Outbreak Due to a CTX-M-14-Producing Strain

Abstract

ABSTRACTLittle information is available about pediatric infections caused by extended-spectrum-β-lactamase (ESBL)-producingEscherichia coli. We characterized an outbreak caused by a CTX-M-14-producingE. coliisolate in a neonatal intensive care unit (NICU) and studied other infections caused by ESBL-producingE. coliin non-NICU pediatric units. All children ≤4 years old who were infected or colonized by ESBL-producingE. coliisolates between January 2009 and September 2010 were included. Molecular epidemiology was studied by phylogroup analysis, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing. Antibiotic resistance genes were analyzed by PCR and sequencing. Plasmids were studied by PFGE with S1 nuclease digestion and by incompatibility group analysis using a PCR-based replicon-typing scheme. Of the ESBL-producingE. coliisolates colonizing or infecting the 30 newborns, identical PFGE results were observed for 21 (70%) isolates, which were classified as CTX-M-14-producingE. coliof ST23 phylogroup A.blaCTX-M-14awas linked to ISEcp1and was carried on an ∼80-bp IncK plasmid. A smaller ongoing outbreak due to SHV-12-producing ST131E. coliwas also identified in the same NICU. Fifteen additional infections with ESBL-producingE. coliwere identified in non-NICU pediatric units, but none was caused by the CTX-M-14-producingE. coliepidemic clone. Overall, CTX-M-14 (71.1%), CTX-M-15 (13.3%), and SHV-12 (13.3%) were the most important ESBLs causing pediatric infections in this study. Infections of newborns with CTX-M-14-producingE. coliwere caused by both clonal and nonclonal isolates.