Phenotypic detection of metallo-beta-lactamase production in clinical isolates of Escherichia coli and Klebsiella pneumoniae in a tertiary care hospital

Introduction: Carbapenem resistance due to metallo-beta-lactamase (MBL)-producing bacteria is an emerging threat worldwide. This study aimed to detect the MBL production in clinical isolates of E. coli and Klebsiella pneumoniae species in our hospital setting and to evaluate the efficiency of two phenotypic methods for the detection of MBL production. Materials and Methods: The present study was carried out in the Department of Microbiology, MGM Medical College and Hospital, Aurangabad, Maharashtra, for a period of 2 years from April 2018 to March 2020. From a total of 12,324 various clinical specimens, 393 isolates of E. coli and Klebsiella pneumoniae species were tested for MBL production. MBL was detected by two different phenotypic methods, i.e., combined disc test and E-test. Results: Out of 393 isolates, 130 (33.07%) isolates were resistant to imipenem on screening of which 71 (18.06%) were Klebsiella pneumoniae and 59 (15.01%) were E. coli. About 43.66% Klebsiella pneumoniae isolates and 40.67% E. coli isolates were MBL-positive by the combined disc test. Using the E-test, MBL production was found to be 46.47% and 45.76% in Klebsiella pneumoniae and E. coli, respectively. Conclusion: Routine screening of MBL-producing organisms should be performed in diagnostic laboratories to control the spread of resistance and for the proper management of antibiotic therapy. E-test is better than the combined disc test for the detection of MBL-producing gram-negative bacilli.