Phenotypic and molecular characteristics of carbapenem-resistant Enterobacteriaceae in a health care system in Los Angeles, California, from 2011 to 2013

S. Pollett, S. Miller, J. Hindler, D. Uslan, M. Carvalho, R. M. Humphries*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

58 Scopus citations

Abstract

Carbapenem-resistant Enterobacteriaceae (CRE) are a concern for health care in the United States but remain relatively uncommon in California. We describe the phenotype, clonality, and carbapenemase-encoding genes present in CRE isolated from patients at a Californian tertiary health care system. CRE for this study were identified by evaluating the antibiograms of Enterobacteriaceae isolated in the UCLA Health System from 2011 to 2013 for isolates that were not susceptible to meropenem and/or imipenem. The identification of these isolates was subsequently confirmed by matrix-associated laser desorption ionization-time of flight, and broth microdilution tests were repeated to confirm the CRE phenotype. Real-time PCR for blaKPC, blaSME, blaIMP, blaNDM-1, blaVIM, and blaOXA-48 was performed. Clonality was assessed by repetitive sequence-based PCR (repPCR) and multilocus sequence typing (MLST). Of 15,839 nonduplicate clinical Enterobacteriaceae isolates, 115 (0.73%) met the study definition for CRE. This number increased from 0.5% (44/8165) in the first half of the study to 0.9% (71/7674) in the second (P = 0.004). The most common CRE species were Klebsiella pneumoniae, Enterobacter aerogenes, and Escherichia coli. A carbapenemase-encoding gene was found in 81.7% (94/115) of CRE and included blaKPC (78.3%), blaNDM-1 (0.9%), and blaSME (2.6%). The majority of blaKPC genes were in K. pneumoniae isolates, which fell into 14 clonal groups on typing. blaKPC was identified in more than one species of CRE cultured from the same patient in four cases. Three blaSME-carrying Serratia marcescens isolates and one blaNDM-1 carrying Providencia rettgeri isolate were detected. CRE are increasing in California, and carbapenemases, particularly KPC, are a common mechanism for carbapenem resistance in this region.

Original languageEnglish
Pages (from-to)4003-4009
Number of pages7
JournalJournal of Clinical Microbiology
Volume52
Issue number11
DOIs
StatePublished - 1 Nov 2014
Externally publishedYes

Fingerprint

Dive into the research topics of 'Phenotypic and molecular characteristics of carbapenem-resistant Enterobacteriaceae in a health care system in Los Angeles, California, from 2011 to 2013'. Together they form a unique fingerprint.

Cite this