Comparative Evaluation of a Prototype Chromogenic Medium (ChromID CARBA) for Detecting Carbapenemase-Producing Enterobacteriaceae in Surveillance Rectal Swabs

Abstract

c 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-g ertapenem disk followed by plating onto MacConkey agar (CDC-TS), (ii) short selective enrichment in 9 ml brain heart infusion broth with a 10-g 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 g/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.

Comparative evaluation of a novel chromogenic medium (chromID OXA-48) for detection of OXA-48 producing Enterobacteriaceae

“…The sensitivity of chromID CARBA was lower than that of SUPERCARBA for detection of OXA-48 producers (Table 2), but it was the same for detection of other classes of carbapenemase producers (90 %, Table 3). This result mirrored that of Vrioni et al (2012) that show that chromID CARBA has an excellent ability to detect KPC and MBL producers (Vrioni et al, 2012).…”

“…OXA-48 producers currently represent a worrisome threat at least in North African countries, the Middle East, Turkey, the Indian subcontinent, and Europe (Poirel et al, 2012). Moreover, the spread of MBL and KPC producers has created an urgent need for reliable screening techniques for detection of any type of carbapenemase producers (Nordmann et al, 2012b;Vatopoulos, 2008;Vrioni et al, 2012;Wilkinson et al, 2012). The chromogenic, carbapenem-containing chromID CARBA medium and the recently developed SUPERCARBA medium which contains ertapenem, cloxacillin and zinc sulfate have been specifically developed for the detection of CPE (Nordmann et al, 2012b).…”

An optimized work-flow to reduce time-to-detection of carbapenemase-producing Enterobacteriaceae (CPE) using direct testing from rectal swabs

“…16,17 Within our laboratory, our current CPE screening process, utilizing selective chromogenic agar (CHROMagar TM KPC, Paris, France) and GeneXpert Ò Carba-R for in-house molecular confirmation of CPE positive specimens (Cepheid, Buckinghamshire, United Kingdom), had an average turnaround time of 48/72 h from specimen arrival in the laboratory to final CPE result for the clinician. The 48/72 h delay in diagnosis was in keeping with other centers worldwide using selective cultures, [18][19][20] but was resulting in use of empiric broad-spectrum antimicrobials and an inefficient use of limited isolation facilities.…”

Vigilancia de enterobacterias productoras de carbapenemasas en cultivos rectales en un hospital universitario de Santiago, Chile

“…Para esto se han diseñado varias técnicas de cultivos, incluyendo medios de agar cromogénico, los que serían menos complejos de realizar, con buena sensibilidad y especificidad reportada hasta la fecha 13 .…”