title: Comparative evaluation of a prototype chromogenic medium (ChromID CARBA) for detecting carbapenemase-producing Enterobacteriaceae in surveillance rectal swabs.
abstract: Carbapenemase-producing Enterobacteriaceae (CPE) are an increasing problem worldwide, and rectal swab surveillance is recommended as a component of infection control programs. The performance of a prototype chromogenic medium (chromID CARBA) was evaluated and compared with media tested by four other screening methods: (i) overnight selective enrichment in 5 ml tryptic soy broth with a 10-μg ertapenem disk followed by plating onto MacConkey agar (CDC-TS), (ii) short selective enrichment in 9 ml brain heart infusion broth with a 10-μg ertapenem disk followed by plating onto chromID ESBL medium (ESBL-BH), (iii) direct plating onto chromID ESBL, and (iv) direct plating onto MacConkey agar supplemented with meropenem (1 μg/ml) (MCM). The screening methods were applied to detect CPE in 200 rectal swab specimens taken from different hospitalized patients. Identification and antimicrobial susceptibility were performed by the Vitek 2 system. Carbapenem MICs were checked by Etest. Carbapenemase production was confirmed using the modified Hodge test, combined-disk tests, and PCR assays. In total, 133 presumptive CPE strains were detected. Phenotypic and genotypic assays confirmed 92 strains to be CPE (56 KPC-positive Klebsiella pneumoniae, 29 VIM-positive K. pneumoniae, and 7 KPC-positive Enterobacter aerogenes strains) recovered from 73 patients, while the remaining 41 strains were confirmed to be CPE negative (19 ESBL producers and 22 nonfermenters). chromID CARBA, ESBL-BH, and chromID ESBL exhibited the highest sensitivity (92.4%), followed by CDC-TS and MCM (89.1%) (P = 0.631). The specificity was greater for chromID CARBA (96.9%) and ESBL-BH (93.2%) than for CDC-TS (86.4%), MCM (85.2%), and chromID ESBL (84.7%) (P = 0.014). In conclusion, chromID CARBA was found to be a rapid and accurate culture screening method for active CPE surveillance.
authors.affiliation: Department of Microbiology, Medical School, University of Athens, Athens, Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Vrioni
authors.forename: Ioannis
authors.initials: I
authors.lastname: Daniil
authors.forename: Evangelia
authors.initials: E
authors.lastname: Voulgari
authors.forename: Kyriaki
authors.initials: K
authors.lastname: Ranellou
authors.forename: Vasiliki
authors.initials: V
authors.lastname: Koumaki
authors.forename: Sandrine
authors.initials: S
authors.lastname: Ghirardi
authors.forename: Maria
authors.initials: M
authors.lastname: Kimouli
authors.forename: Gilles
authors.initials: G
authors.lastname: Zambardi
authors.forename: Athanassios
authors.initials: A
authors.lastname: Tsakris
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001431:Bacteriological Techniques / Q000379:methods*; D015780:Carbapenems / Q000494:pharmacology; D003470:Culture Media / Q000737:chemistry*; D021902:Enterobacter aerogenes; D004755:Enterobacteriaceae / Q000201:enzymology* / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000382:microbiology*; D005838:Genotype; D006801:Humans; D007711:Klebsiella pneumoniae; D008403:Mass Screening / Q000379:methods; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012007:Rectum / Q000382:microbiology*; D012680:Sensitivity and Specificity; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D015780:Carbapenems; D003470:Culture Media; D001618:beta-Lactamases; C063912:carbapenemase