Presence and characterisation of extended spectrum beta-lactamase producing Gram-negative bacteria obtained from water in selected storage tanks

Objective: To detect the presence of extended-spectrum beta-lactamase-producing Gram-negative bacteria in water from selected storage tanks in Ogun State, Nigeria. Methods: MacConkey agar supplemented with 6 pg/mL of cefotaxime was used to isolate bacteria. Pure isolates were identified through PCR amplification. The susceptibility patterns of the isolates to ceftazidime (30 μg/mL), amoxicillin/clavulanate (30 μg/mL), tetracycline (30 μg/mL), cefotaxime (30 μg/mL), cefpodoxime (10 μg/mL), and ciprofloxacin (5 μg/mL) were evaluated using the Kirby-Bauer disc diffusion method, while the identification of beta-lactamase production was performed using the double disc synergy test. Results: A total of 19 isolates belonging to four genera ( Citrobacter, Pseudomonas, Escherichia , and Serratia ) were obtained from the ten water samples. Escherichia coli and Citrobacter spp. had the highest presence (30.0%). The antibiotic with highest resistance was observed to be cefpodoxime (100%) followed by amoxicillin/clavulanate (89.5%) and cefotaxime (89.5%), the least was noted with tetracycline (31.6%). Additionally, 10 (52.6%) out of the 19 isolates showed beta-lactamase-producing phenotypic properties with high resistance to cefpodoxime (100%), amoxicillin/clavulanate (100%) and ceftazidime (90.0%). Additionally, this study showed the link between bacterial strains identified by 16S rRNA and related human diseases, highlighting the importance of genetic identification in managing infections. Conclusions: This study highlights the prevalence of beta-lactam-resistant bacteria, emphasizing the urgent need for proactive measures to address this issue.