Detection of Metallo-beta-lactamase Producers Among Clinical Isolates of Enterobacterales in a Tertiary Care Centre, Nepal

Background and Objective: Increased reports of metallo-beta-lactamase (MBL)-producing isolates of Enterobacterales indicate that there are limited therapeutic options available for the treatment of infections caused by these organisms. To the best of our knowledge, there have been only a limited number of studies on MBL-producing Enterobacterales in Nepal. Therefore, this study was conducted to determine the current distribution of MBL-producing isolates in our setting. Methods: This was a cross-sectional study conducted over a period of six months (from August 2023 to January 2024) at the Department of Microbiology, TU Teaching Hospital, Nepal. A total of 243 clinical isolates of Enterobacterales from various clinical specimens were subjected to the Modified Carbapenem Inactivation Method (mCIM) and the EDTA-Modified Carbapenem Inactivation Method (eCIM) for the detection of MBL-producing isolates, according to the standard methodology outlined by the latest Clinical and Laboratory Standards Institute (CLSI) guidelines. Result: A total of 111 (45.70%) isolates were identified as potential carbapenemase producers, based on their resistance or intermediate susceptibility to carbapenems (Meropenem and/or Imipenem) and/or resistance to cephalosporin subclass III (Ceftazidime). Among the total isolates of Enterobacterales, 52 (21.40%) were confirmed as carbapenemase producers by the mCIM method, 45 (18.50%) were confirmed as MBL producers by the eCIM method, while the remaining 7 (2.90%) were identified as serine-carbapenemase producers. Multidrug resistance (MDR) was observed in 151 (62.10%) of the total isolates, and all MBL-producing isolates were also MDR. Conclusion: This study found a higher percentage of MBL-producing Enterobacterales isolates, along with a high prevalence of multidrug resistance. Regular surveillance and stringent infection control policies are essential to minimize the spread of resistant strains.

Detection of Metallo-beta-lactamase Producers Among Clinical Isolates of Enterobacterales in a Tertiary Care Centre, Nepal Keywords:

carbapenemase , eCIM , Enterobacterales , mCIM , MDR , phenotypic detection of MBL.