Microbiological and Physicochemical Assessment of Antibiotic-Resistant Bacteria in Hospital Wastewater: A Case Study from Sabratha Teaching Hospital, Libya

Abstract

Background: Antimicrobial resistance (AMR) is a growing global public health crisis, with hospital wastewater increasingly recognized as a critical environmental reservoir of antibiotic-resistant bacteria.

Objective: This study aimed to assess the microbiological and physicochemical characteristics of hospital wastewater from Sabratha Teaching Hospital, Libya, and to evaluate their association with antibiotic resistance patterns.

Methods: A descriptive analytical laboratory-based study was conducted between June and August 2025. Wastewater samples were collected from three major discharge points within the hospital sewage system. Bacterial isolation and identification were performed using standard microbiological techniques. Antibiotic susceptibility testing was carried out according to Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. Physicochemical parameters, including pH, total dissolved solids (TDS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), and dissolved oxygen (DO), were analyzed. Statistical analysis included descriptive statistics, correlation analysis, regression modeling, and time-series forecasting.

Results: A total of 62 bacterial isolates representing six clinically significant genera were identified, with Escherichia coli being the predominant species. High levels of multidrug resistance (MDR) were observed, particularly among Pseudomonas spp. and Acinetobacter spp., with elevated Multiple Antibiotic Resistance Index (MARI) values in samples from intensive care and emergency units. Significant discrepancies were observed between CLSI and EUCAST interpretations. A strong positive correlation was found between COD and BOD, indicating high organic pollution. COD was negatively associated with antibiotic susceptibility, whereas DO showed a positive correlation. Multivariate analysis identified COD as the strongest predictor of resistance patterns.

Conclusion: Hospital wastewater at Sabratha Teaching Hospital represents a significant hotspot for antibiotic-resistant bacteria. Both microbiological and physicochemical factors contribute to resistance dynamics. These findings highlight the urgent need for wastewater treatment systems, continuous environmental surveillance, and integrated antimicrobial stewardship strategies to mitigate ecological and public health risks.