Prevalence of NDM-1 carbapenemase in patients with diarrhoea in Pakistan and evaluation of two chromogenic culture media

Abstract

To evaluate two chromogenic media, Brilliance CRE and chromID CARBA, with stool samples referred to the Public Health Laboratories Division of the National Institute of Health in Islamabad, and assess the prevalence of carbapenemase-producing Enterobacteriaceae (CPE) in this population. One hundred and fifty-two stool samples from patients with diarrhoea were referred to the Microbiology Department and were investigated for the presence of CPE using two chromogenic culture media, Brilliance CRE and chromID CARBA. Thirteen patients (8·6%) were found to be colonized with CPE and all produced NDM-1 carbapenemase. Twelve of these patients (92%) were found to be colonized by culture on chromID CARBA compared with seven (54%) using Brilliance CRE. If only coloured colonies were considered as presumptive CPE, the sensitivity, specificity and positive predictive value were 54, 23 and 6% for Brilliance CRE and 85, 85 and 36% for chromID CARBA, respectively. We conclude that Enterobacteriaceae that produce NDM-1 carbapenemase can be found in patients from all major provinces of Pakistan and that chromID CARBA was the most effective of the two chromogenic media in this setting.