ANTIMICROBIAL RESISTANCE IN HOSPITAL AND MUNICIPAL WASTEWATER

Abstract

Objective: To compare the occurrence of antibiotic-resistant bacteria and selected antimicrobial resistance genes in hospital and municipal wastewater.

Methods: This comparative cross-sectional laboratory-based study was conducted at the University of Sindh, Jamshoro, Pakistan. Eighty wastewater samples, comprising 40 hospital and 40 municipal samples, were analyzed. Gram-negative bacteria were isolated and identified using standard microbiological procedures. Antimicrobial susceptibility was determined by the Kirby–Bauer disk diffusion method. Multidrug-resistant (MDR) isolates were subjected to PCR for detection of blaTEM, blaCTX-M, qnrS, tetA, and sul1.

Results: A total of 126 bacterial isolates were recovered, including 72 from hospital and 54 from municipal wastewater. MDR was significantly more frequent among hospital isolates than municipal isolates (68.1% vs. 46.3%; p=0.014; OR=2.49). Resistance to ceftriaxone, ceftazidime, ciprofloxacin, meropenem, tetracycline, and trimethoprim-sulfamethoxazole was significantly higher in hospital wastewater. Among 74 MDR isolates, blaTEM was most prevalent (58.1%), followed by blaCTX-M (51.4%), sul1 (47.3%), tetA (41.9%), and qnrS (35.1%).

Conclusion: Hospital wastewater demonstrated a greater burden of MDR bacteria and resistance genes than municipal wastewater, highlighting the importance of incorporating wastewater monitoring into environmental antimicrobial resistance surveillance.