Molecular Detection and Statistical Association of Carbapenem Resistance Determinants (blaOXA and blaNDM) in Clinical Isolates of Escherichia coli and Klebsiella pneumoniae from Southeastern Nigeria

Henrietta Uzoeto; Ismaila Danjuma Mohammed; Onyinye Lovette Nomeh; Ikemesit Udeme Peter

Henrietta Uzoeto Department of Microbiology, Federal University of Allied Health Sciences, Enugu State, Nigeria https://orcid.org/0000-0001-8897-1773
Ismaila Danjuma Mohammed Department of Nursing Sciences, Federal University of Lokoja, Kogi State, Nigeria https://orcid.org/0009-0008-5571-5536
Onyinye Lovette Nomeh Department of Microbiology, Alex Ekwueme Federal University, Ebonyi State, Nigeria https://orcid.org/0009-0007-5495-8168
Ikemesit Udeme Peter Department of Microbiology, Federal University of Allied Health Sciences, Enugu State, Nigeria https://orcid.org/0000-0001-9890-8786

Keywords: Carbapenem resistance, blaNDM, blaOXA, Escherichia coli, Klebsiella pneumoniae

Abstract

Background: Carbapenem-resistant Enterobacteriaceae (CRE) represent a critical public health threat, with limited epidemiological data from southeastern Nigeria. This study investigated the prevalence of carbapenem resistance and the distribution of blaOXA and blaNDM genes among clinical isolates of Escherichia coli and Klebsiella pneumoniae from a tertiary hospital in Enugu, Enugu State.

Methods: A total of 210 non-duplicate urine samples were collected from patients attending Enugu State University Teaching Hospital (ESUTH). Bacterial isolates were identified using standard microbiological techniques and API 20E system. Antimicrobial susceptibility testing was performed by disk diffusion method, with carbapenem resistance phenotypically confirmed using the Modified Hodge Test. Molecular detection of blaOXA and blaNDM genes was conducted using conventional PCR. Statistical associations between resistance phenotypes and demographic variables were analyzed using SPSS version 25.

Results: Gram-negative bacteria were isolated from 151 (71.9%) samples, comprising 89 (42.4%) E. coli and 62 (29.5%) K. pneumoniae. Phenotypic carbapenem resistance was detected in 24 (15.9%) isolates: 10 (11.2%) E. coli and 14 (22.6%) K. pneumoniae. All carbapenem-resistant isolates exhibited multidrug resistance phenotypes. Molecular analysis revealed that 21 (87.5%) of phenotypically resistant isolates harbored carbapenemase genes: blaNDM was detected in 12 (50.0%) isolates, blaOXA in 5 (20.8%), and co-occurrence of both genes in 4 (16.7%). K. pneumoniae demonstrated significantly higher gene carriage (92.9%) compared to E. coli (80.0%). Statistical analysis showed significant association between carbapenem resistance and patient age >40 years (p=0.023), but not with gender (p=0.412).

Conclusion: This study documents a high prevalence of blaNDM and blaOXA genes among CRE isolates in southeastern Nigeria, with K. pneumoniae serving as a major resistance reservoir. The findings underscore the urgent need for enhanced surveillance, antimicrobial stewardship, and infection control measures in the region.

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