Laboratory-based surveillance of carbapenem resistance in clinical enterobacterales strains in a Nigerian tertiary hospital: Detection of blaNDM and blaVIM genes

Background: Carbapenem-resistant enterobacterales (CRE) are a critical priority that require continuous surveillance to track their dissemination and to guide antimicrobial chemotherapy and infection prevention and control measures. This study determines the species diversity and the prevalence of carbapenem resistance among enterobacterales from patients attending the Federal Teaching Hospital Gombe (FTHG) in Northeastern Nigeria. Methods: In this cross-sectional laboratory-based surveillance conducted from 1 June to 1 October 2024, 223 non-replicative Gram-negative bacteria (GNB) were recovered from various clinical samples of patients attending FTHG. These isolates were identified using the API 20E system. Meropenem-resistant strains were subjected to the Modified Hodge Test to detect carbapenemase activity phenotypically. Other antimicrobial resistance phenotypes were determined by the disk diffusion method, and the presence of carbapenem resistance genes was assessed by multiplex PCR. Multivariate regression tests were used to assess the association between carbapenemase production and enterobacterales species. Results: Of the GNB, 87 (39%) were enterobacterales, with 39% being Escherichia coli, 20% Klebsiella (K.) oxytoca, and 18% K. pneumoniae. About 19.5% of enterobacterales (17/87) were phenotypically resistant to meropenem, of which 10 (58.8%) were carbapenemase producers. The carbapenemase producers had the highest rates of resistance to amoxicillin-clavulanate (70%), gentamicin (50%), ceftazidime (40%), and ciprofloxacin (40%), and 50% (5/10) exhibited multidrug resistance (MDR). Of the MDR carbapenemase-producers, blaNDM and blaVIM genes were detected in Serratia (S.) odorífera, Enterobacter cloacae, S. marcescens from urine samples and Proteus mirabilis and K. oxytoca from blood culture. Conclusion: A high frequency of CRE was identified, with some simultaneously resistant to third-generation cephalosporins. Remarkably, the blaNDM- and blaVIM-genes were found in non-conventional enterobacterales. These indicate their evolving roles as reservoirs of carbapenem-resistance genes, underscoring the need for a broader surveillance scope and improved antimicrobial stewardship in the hospital.