Prevalence of Gram-negative bacteria in drinking water in Mosul city and their resistance to chlorine and antibiotics

Taqi, Abbas Hasan; Alwan, Angham J; Essa, Muhsin A

doi:10.33899/rjs.2025.158543.1430

	Prevalence of Gram-negative bacteria in drinking water in Mosul city and their resistance to chlorine and antibiotics
Rafidain Journal of Science
Articles in Press, Accepted Manuscript, Available Online from 02 August 2025
Document Type: Research Paper
DOI: 10.33899/rjs.2025.158543.1430
Authors
Abbas hasan Taqi^* ¹; angham J alwan²; muhsin A essa³
¹Biology Dept./Science College /Mosul University
²department of biology/ college of science/ univocity of Mosul
³department of biology/ college of science/ university of mosul
Abstract
This study was conducted to investigate the Gram-negative bacteria, determine their prevalence in drinking water supplied to various areas in Mosul city , and determine their resistance to both chlorine and antibiotics. For this purpose, drinking water samples were collected from seventeen locations representing both sides of Mosul city. Residual chlorine concentrations in these samples were measured, and membrane filtration method was used to detect contamination. The results showed that all samples under study were contaminated with Gram-negative bacteria at different levels depending on the sampling location. The most contaminated sample was the Nahrawan region sample (240 CFU/100 ml), while the least was the Sumer region sample (3 CFU /100 ml). Contamination values in samples from other regions ranged between these two values. Residual chlorine concentrations in the studied samples ranged from zero to 1.0 mg/cm3. The Gram-negative bacteria isolated and identified using the Vitek2 compact system from contaminated drinking water samples were Escherichia coli and Klebsiella pneumoniae, both belonging to the Enterobacteriaceae ; Aeromonas hydrophilia, belonging to the Aeromonadaceae; and Acinetobacter baumannii, belonging to the Moraxellaceae. The four studied bacteria showed resistant to chlorine concentrations up to 0.8 mg/cm³, which explained their presence in studied contaminated drinking water samples and all of these bacteria were became sensitive to chlorine at a concentration of 1 mg/cm³, and their sensitivity increased with increasing concentration. Antibiotic sensitivity tests showed that all bacteria were sensitive to seven types of antibiotics, while they were resistant to penicillin, ampicillin-sulbactum, and amoxicillin-clavulanate
Keywords
Gram-negative bacteria; drinking water; chlorine; and antibiotics

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