Detection of NDM Variants ( , , ) from Carbapenem-Resistant and : First Report from Nepal.

Background: Increasing burden of carbapenem resistance among is attributable to their ability to produce carbapenemase enzymes like metallo-beta-lactamase (MBL), carbapenemase (KPC), and OXA-type. This study aimed to determine the prevalence of carbapenemases and MBL genes (( and ) among and isolates.

Methods: A total of 2474 urine samples collected during the study period (July-December 2017) were processed at the microbiology laboratory of Kathmandu Model Hospital, Kathmandu. Isolates of and were processed for antimicrobial susceptibility testing (AST) by disc diffusion method. Carbapenem-resistant isolates were subjected to Modified Hodge Test (MHT) for phenotypic confirmation, and inhibitor-based combined disc tests for the differentiation of carbapenemase (MBL and KPC). MBL-producing isolates were screened for NDM genes by polymerase chain reaction (PCR).

Results: Of the total urine samples processed, 19.5% (483/2474) showed the bacterial growth. (72.6%; 351/483) was the predominant isolate followed by (12.6%; 61/483). In AST, 4.4% (18/412) isolates of (15/351) and (3/61) showed resistance towards carbapenems, while 1.7% (7/412) of the isolates was confirmed as carbapenem-resistant in MHT. In this study, all (3/3) the isolates of were KPC-producers, whereas 66.7% (10/15), 20% (3/15) and 13.3% (2/15) of the isolates were MBL, KPC and MBL/KPC (both)-producers, respectively. In PCR assay, 80% (8/10), 90% (9/10) and 100% (10/10) of the isolates were positive for , and respectively.

Conclusion: Presence of NDM genes among carbapenemase-producing isolates is indicative of potential spread of drug-resistant variants. This study recommends the implementation of molecular diagnostic facilities in clinical settings for proper infection control, which can optimize the treatment therapies, and curb the emergence and spread of drug-resistant pathogens.