title: Laboratory detection of Enterobacteriaceae that produce carbapenemases.
abstract: A study was designed to evaluate the modified Hodge test (MHT), Mastdiscs ID inhibitor combination disks (MDI), Rosco Diagnostica Neo-Sensitabs (RDS), metallo-β-lactamase (MBL) Etest, and in-house multiplex PCR for the detection of well-characterized carbapenemase-producing Enterobacteriaceae. One hundred forty-two nonrepeat clinical isolates of carbapenemase-producing Enterobacteriaceae (including Klebsiella spp., Escherichia coli, Citrobacter freundii, and Enterobacter spp.) obtained from the SMART worldwide surveillance program during 2008 to 2009 were included. These included 49 KPC-, 27 NDM-, 19 VIM-, 14 OXA-48-like enzyme-, and 5 IMP-producing isolates and 28 carbapenem-resistant, carbapenemase-negative isolates. The manufacturer's instructions were followed for MDI, RDS, and MBL Etest and CLSI guidelines for MHT. A multiplex PCR was designed to detect KPC, NDM, VIM, IMP, and OXA-48-like carbapenemases. Overall, the sensitivity and specificity were 78% and 93% for MDI, 80% and 93% for RDS, 58% and 93% for MHT, and 55% and 100% for MBL Etest, respectively. The PCR had 100% sensitivity and specificity. MDI and RDS performed well for the detection of KPCs and NDMs but poorly for VIMs, IMPs, and OXA-48-like enzymes. MHT performed well for KPCs and OXA-48-like enzymes but poorly for NDMs, VIMs, and IMPs. MDI and RDS were easy to perform and interpret but lacked sensitivity for OXA-48-like enzymes, VIMs, and IMPs. MHT and MBL Etest were often difficult to interpret. We recommend using molecular tests for the optimal detection of carbapenemase-producing Enterobacteriaceae.
authors.affiliation: Division of Microbiology, Calgary Laboratory Services, Calgary, Alberta, Canada.
authors.forename: Diana
authors.initials: D
authors.lastname: Doyle
authors.forename: Gisele
authors.initials: G
authors.lastname: Peirano
authors.forename: Christine
authors.initials: C
authors.lastname: Lascols
authors.forename: Tracie
authors.initials: T
authors.lastname: Lloyd
authors.forename: Deirdre L
authors.initials: DL
authors.lastname: Church
authors.forename: Johann D D
authors.initials: JD
authors.lastname: Pitout
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001431:Bacteriological Techniques / Q000379:methods*; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000382:microbiology*; D005838:Genotype; D006801:Humans; D060885:Multiplex Polymerase Chain Reaction / Q000379:methods*; D010641:Phenotype; D012680:Sensitivity and Specificity; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D001618:beta-Lactamases; C063912:carbapenemase