Rapid Screening for Carbapenem Resistant Organisms: Current Results and Future Approaches

Carbapenem producing Enterobacteriaceae (CPE) is a major public health threat. A total of 120 carbapenem resistant E. coli (n=32) and K. pneumoniae (n=88) from blood stream infections were screened for the presence of carbapenem resistant genes KPC, NDM, IMP, VIM, and OXA-48 like using both conventional multiplex PCR and Xpert (R) Carba-R test. Additionally 26 faeces samples were directly screened with Xpert (R) Carba-R test. Of the tested isolates, 40% (n=48) of NDM and 39.2% (n=47/) of OXA-48-like were identified. Co-production of OXA-48 and NDM was seen in 15 (12.5%) isolates. In Xpert (R) Carba-R test, only NDM was identified in 55% (n=66) of tested isolates. Of the tested faeces samples, 12 were identified as carbapenemase producers: nine with NDM, two with the co-production of NDM and VIM and in Klebsiella spp (n=1), NDM and KPC co-production was seen. However, Xpert (R) Carba-R test fails to detect OXA-48 like as compared with multiplex PCR. The sensitivity, specificity, PPV, NPV of Xpert (R) Carba-R test was 100%, 77%, 96% and 100% respectively. Incorporation of OXA-48 like specific sequence in the panel of Xpert (R) Carba-R test may improve its sensitivity and maximize the coverage of assay.