Molecular characterization of antibiotic-resistant gram-negative bacteria isolated from Lake Nokoué and surrounding environments in Benin

The spread of antimicrobial-resistant bacteria in natural and human-impacted environments poses a significant threat to global public health. This study aimed to characterize Gram-negative bacteria isolated from various sources around Lake Nokoué in southern Benin. A total of 116 samples were collected from hospital effluents, watercourses, feces, fish, and sediments from Lake Nokoué. Bacteria were identified, and their antimicrobial resistance was assessed using disk diffusion tests. The presence of resistance genes was further detected by PCR. Among the 140 bacterial isolates identified, the majority were derived from water (21.42%), wastewater (19.28%), and feces (19.28%). The predominant species included Escherichia coli (32.85%) and Klebsiella pneumoniae (30.71%), all of which exhibited high resistance to ampicillin (76.63%), amoxicillin-clavulanic acid (53.33%), and gentamicin (60.74%). PCR analysis revealed the presence of multiple resistance genes, with blaTEM, blaSHV, and blaOXA being the most prevalent. Carbapenem resistance gene blaVIM was detected in a Pseudomonas putida strain obtained from animal feed. These findings underscore Lake Nokoué’s role as a reservoir for bacteria harboring clinically relevant antibiotic resistance genes, highlighting the need for urgent environmental and public health interventions.