Multidrug-resistant Enterobacterales causing wound infections in Ibadan, Nigeria:Phenotypic resistance and detection of blaKPC, blaOXA-48 and mcr genes

Abstract

ABSTRACT Background Carbapenem- and colistin-resistant Enterobacterales remain an important challenge in the management of wound infections in resource-limited settings. Objective This study determined the species, antimicrobial resistance (AMR) phenotypes, and genotypes of antimicrobial-resistant Enterobacterales, as well as factors associated with Enterobacterales-positive wounds in Ibadan, southwestern Nigeria. Methods Two hundred and twenty-one non-repetitive wound swabs and biopsies obtained from patients were processed to recover bacteria, which were identified using the API 20E system. AMR phenotypes and mechanisms were determined by the Kirby-Bauer disk diffusion method and polymerase chain reactions, respectively. Structured questionnaires were used to collect patients’ sociodemographic data and risk-factor data. Results One hundred and seventy-five (79.2%) samples were culture-positive. Enterobacterales accounted for 42.3% of isolates (74/175), with Klebsiella spp. (47.3%), Escherichia coli (32.4%) and Proteus mirabilis (20.3%) predominated. Of the 74 Enterobacterales, resistance was highest (>91%) against third-generation cephalosporins and amoxicillin - clavulanate, nalidixic acid (90.5%), gentamicin (81.1%), and imipenem (80%). About 25.7% (19/74) presented an MDR phenotype; the following resistance genes were detected: qnrB (84.2%), bla KPC (57.9%), aac (6’)-Ib (52.6%), bla OXA-48 (36.8%), qnrC (10.5%), mcr-2 (10.5%), qepA (5.3%), and mcr-1 (5.3%). The co-occurrence of carbapenemase and mcr genes indicates potential for highly drug-resistant strains . A significant association was observed between Enterobacterales wound infections and diabetes mellitus (OR = 5.81; 95% CI: 0.76–44.35; p = 0.034). Conclusions MDR-Enterobacterales account for about a quarter of the etiological agents of wound infections, with major implications for surgical site infections, as their extensive resistance profiles threaten the effectiveness of empirical therapy, increase the risk of treatment-refractory postoperative infections, and facilitate rapid hospital spread. The detection of Enterobacterales of critical priority carrying colistin- and carbapenem-resistance genes underscores the need for local genomic surveillance to monitor and control their spread; coordinated health system planning to ensure sustained access to effective antibiotics; strengthening infection prevention and control practices; improving antimicrobial stewardship; and implementing targeted patient-level risk-factor management.