Bacteriological quality, antimicrobial resistance profile of Escherichia coli, and associated risk factors in tap water, Addis Ababa, Ethiopia

In low and middle-income countries, access to clean and microbiologically safe drinking water remains a major challenge. Contaminated drinking water promotes the transmission of waterborne pathogens and the dissemination of antimicrobial-resistant bacteria, which is a global concern. Between May and July 2024, a cross-sectional study was conducted to determine the bacteriological quality of tap water, antimicrobial resistance patterns of E. coli, and associated risk factors in Gulelle and Yeka sub-cities of Addis Ababa, Ethiopia. A total of 341 household tap water samples were collected and processed for bacteriological quality assessment following standard microbiological procedures. Coliforms were isolated using membrane filtration, and aerobic colony counts (ACC) were determined via the pour plate method. Antimicrobial susceptibility testing was performed using the Kirby-Bauer method. Statistical analysis was performed using SPSS version 27, with logistic regression identifying significant associations (p < 0.05). Bacteriological contaminations of tap water were found to be 18.8% (n=64/341) for total coliforms, 14.7% (n=50/341) for thermotolerant coliforms, 8.8% (n=30/341) for E. coli, and 81.5% (n=278/341) for ACC. E. coli isolates showed the highest resistance to amoxicillin (100%), ampicillin (80%), and nitrofurantoin (70%) while exhibiting 100% susceptibility to ciprofloxacin and gentamicin. Additionally, the E. coli isolates demonstrated moderate sensitivity to Ceftriaxone (60.0%) and Cefepime (73.0%), respectively. Significant associations with contamination were identified, including damaged pipes (AOR: 9.9, 95% CI: 4.09–24.15), the proximity of latrines to water sources (AOR: 7.19, 95% CI: 2.93–17.64), and inadequate waste management practices (AOR: 2.5, 95% CI: 1.02–6.3). A high level of bacterial contamination, including E. coli, and antimicrobial resistance was observed in drinking tap water, highlighting the need for continuous sanitary inspections to prevent waterborne infections and the spread of antimicrobial resistance within the community.