Prevalence of Gram-Negative Bacteria in Drinking Water in Mosul City and Their Resistance to Chlorine and Antibiotics

This study aimed to assess the prevalence of Gram-negative bacteria in drinking water supplied to different areas of Mosul city and to evaluate their resistance to chlorine and selected antibiotics. Drinking water samples were collected from 17 locations representing both sides of the city. Residual chlorine concentrations were measured, and bacterial contamination was determined using the membrane filtration method. The results revealed that all samples were contaminated with Gram-negative bacteria at varying levels depending on the sampling site. The highest level of contamination was recorded in the Nahrawan area (240 CFU/100 mL), while the lowest was observed in the Sumer area (3 CFU/100 mL). Residual chlorine concentrations in the analyzed samples ranged from 0 to 1.0 mg/L. Bacterial isolates identified using the VITEK® 2 Compact system included Escherichia coli and Klebsiella pneumoniae (Enterobacteriaceae), Aeromonas hydrophila (Aeromonadaceae), and Acinetobacter baumannii (Moraxellaceae). All isolated bacteria exhibited resistance to chlorine concentrations up to 0.8 mg/L, whereas complete sensitivity was observed at a concentration of 1.0 mg/L, with increased susceptibility at higher concentrations. Antibiotic susceptibility testing demonstrated that all isolates were sensitive to seven antibiotics but showed resistance to penicillin, ampicillin-sulbactam, and amoxicillin-clavulanate.

This study aimed to assess the prevalence of  Gram-negative bacteria in drinking water supplied to different areas of Mosul city and to evaluate their resistance to chlorine and selected antibiotics. Drinking water samples were collected from 17 locations representing both sides of the city. Residual chlorine concentrations were measured, and bacterial contamination was determined using the membrane filtration method.