title: Phenotypic and molecular characteristics of carbapenem-resistant Enterobacteriaceae in a health care system in Los Angeles, California, from 2011 to 2013.
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 bla(KPC), bla(SME), bla(IMP), bla(NDM-1), bla(VIM), and bla(OXA-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 bla(KPC) (78.3%), bla(NDM-1) (0.9%), and bla(SME) (2.6%). The majority of bla(KPC) genes were in K. pneumoniae isolates, which fell into 14 clonal groups on typing. bla(KPC) was identified in more than one species of CRE cultured from the same patient in four cases. Three bla(SME)-carrying Serratia marcescens isolates and one bla(NDM-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.
authors.affiliation: Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Pollett
authors.affiliation: Pathology & Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA.
authors.forename: S
authors.initials: S
authors.lastname: Miller
authors.affiliation: Pathology & Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA.
authors.forename: J
authors.initials: J
authors.lastname: Hindler
authors.affiliation: Division of Infectious Diseases, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA.
authors.forename: D
authors.initials: D
authors.lastname: Uslan
authors.affiliation: Pathology & Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA.
authors.forename: M
authors.initials: M
authors.lastname: Carvalho
authors.affiliation: Pathology & Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA rhumphries@mednet.ucla.edu.
authors.forename: R M
authors.initials: RM
authors.lastname: Humphries
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D015780:Carbapenems / Q000494:pharmacology*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics; D003695:Delivery of Health Care; D004755:Enterobacteriaceae / Q000145:classification* / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology*; D005838:Genotype; D006801:Humans; D015141:Los Angeles / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D060888:Real-Time Polymerase Chain Reaction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D062606:Tertiary Care Centers; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D004269:DNA, Bacterial; D001618:beta-Lactamases; C063912:carbapenemase