title: Utility of a novel multiplex TaqMan PCR assay for metallo-β-lactamase genes plus other TaqMan assays in detecting genes encoding serine carbapenemases and clinically significant extended-spectrum β-lactamases.
abstract: Prompt detection of infections caused by Enterobacteriaceae that produce therapeutically important β-lactamases [metallo-β-lactamases (MBLs), serine carbapenemases, acquired AmpC and CTX-M extended-spectrum β-lactamases (ESBLs)] is crucial for infection prevention and control and surveillance purposes, and, more contentiously, also for effective patient management. A novel TaqMan PCR assay was developed to detect genes encoding IMP, VIM, NDM, SPM, SIM and GIM MBLs. Published PCR assays for acquired genes encoding CTX-M ESBLs and AmpC β-lactamases were updated and adapted to the TaqMan format, respectively. A published TaqMan assay for serine carbapenemase genes was used. Assay specificity was tested using a panel of 59 isolates with known acquired genes from the four different β-lactamase groupings. The four TaqMan assays correctly identified the most clinically relevant acquired β-lactamase genes in the panel of 59 resistant Enterobacteriaceae, which included 3 VIM-, 7 NDM- and 12 IMP-producers. Consecutive, non-duplicate isolates of Enterobacteriaceae from 965 urinary and 343 blood cultures during 2010 were then screened for β-lactamase genes using these TaqMan assays. Amongst the urinary and blood culture isolates tested, 69 CTX-M-producers and 21 acquired AmpC β-lactamase-producers were identified; the CTX-M rate amongst blood culture isolates (9.3%) broadly reflects the UK national average. During the study period, one Klebsiella pneumoniae isolate producing an NDM carbapenemase was identified from a wound sample. The assays developed and/or used will enable the future surveillance and the rapid detection and appropriate early treatment of infections caused by Gram-negative bacteria producing clinically important β-lactamases, including carbapenemases.
authors.affiliation: Cambridge Public Health and Microbiology Laboratory, Public Health England, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: Rosemary
authors.initials: R
authors.lastname: Swayne
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Ellington
authors.forename: Martin D
authors.initials: MD
authors.lastname: Curran
authors.forename: Neil
authors.initials: N
authors.lastname: Woodford
authors.forename: Sani H
authors.initials: SH
authors.lastname: Aliyu
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D001769:Blood / Q000382:microbiology; D004755:Enterobacteriaceae / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000382:microbiology; D006801:Humans; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D016133:Polymerase Chain Reaction / Q000379:methods*; D006113:United Kingdom; D014556:Urine / Q000382:microbiology; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001618:beta-Lactamases
keywords: Carbapenemases; Cephalosporinases; Enterobacteriaceae; Extended-spectrum β-lactamases; Metallo-β-lactamases