Characterization of multiple drug resistant Enterobacter spp. from treated and untreated hospital wastewater in Babylon Province, Iraq

Background: Hospitalized patients are more likely to carry multidrug-resistant bacteria in their urine and feces than the general population, making hospital wastewater a potential contributor to the spread of antibiotic-resistant bacteria and antimicrobial resistance genes. However, it remains unclear whether hospital sewage plays a significant role in increasing the number and variety of antibiotic resistance genes in the overall sewage system. Objectives: This study compared the prevalence and drug resistance trends of Enterobacter spp. isolated from untreated and treated hospital wastewaters. Methods: A total of 56 wastewater samples were collected from two hospitals between March and November 2024, yielding 26 Enterobacter spp. isolates. Bacterial identification and antibiotic susceptibility testing were performed using the automated VITEK-2 system. The ability of the isolates to form biofilms was quantified using the microtiter plate method. Results: Enterobacter spp isolates were more prevalent in the untreated wastewater (84.62%) than in the treated effluent (15.38%). A significant proportion (84.62%) of the untreated wastewater was biofilm-producing. A highly significant correlation (p<0.01) was observed between biofilm formation and resistance to several antibiotics. Furthermore, 50% of the isolates from untreated wastewater were MDR, with 46.15% resistant to five or more antibiotic classes. Conclusion: Improving policy for handling Hospital wastewater is a significant reservoir of MDR and biofilm-producing Enterobacter spp. Current treatment processes are insufficient to eliminate these resistant pathogens, highlighting a substantial public health risk and urgent need for enhanced wastewater management strategies in healthcare facilities.