Isolation and Characterisation of Bacteria from Hospital Wastewater in Ahmadu Bello University Teaching Hospital, Zaria

Hospital wastewater constitutes a concentrated reservoir of pathogenic bacteria, antimicrobial residues, and resistance genes that pose significant environmental and public health risks if discharged without adequate treatment. This study isolates and characterises bacteria from wastewater samples collected at the Ahmadu Bello University Teaching Hospital (ABUTH), Zaria, Kaduna State, North West Nigeria. Wastewater samples were collected from the surgical ward drain, laboratory effluent point, and final discharge point over three months. Standard dilution plating, differential and selective media, and biochemical characterisation were used for bacterial isolation and identification. Antibiotic susceptibility testing was performed on all isolates using the disk diffusion method. A diverse bacterial community was recovered, with Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterococcus faecalis as dominant species. Extended-spectrum beta-lactamase (ESBL) producers were detected in 41 percent of gram-negative isolates using the double disk synergy test. Pseudomonas aeruginosa demonstrated the broadest resistance profile, with resistance to seven of ten tested antibiotics. Bacterial load at the final discharge point remained high, suggesting inadequate wastewater treatment infrastructure. The study raises concerns about the hospital's effluent entering the Zaria municipal drainage network. Recommendations include installation of functional wastewater treatment plants at ABUTH and regular monitoring of effluent microbial quality. Keywords: hospital wastewater, ESBL, Pseudomonas aeruginosa, ABUTH, antibiotic resistance