This study investigates the microbial quality of mineral waters and bottled drinking water in Ilam city and identifies antibiotic-resistant strains of coliforms. For this purpose, out of 100 samples from different brands of bottled water, 31% of the samples had microbial loads exceeding the permissible limit, including 14% contamination with E. coli bacteria as an indicator of fecal contamination. To assess microbial contamination and identify species, standard microbiological methods were used along with molecular techniques such as PCR and 16S rRNA gene sequencing. The samples included 39 mineral waters, 42 drinking waters, 11 carbonated waters, and 8 flavored waters. The methodology included collecting samples from stores, amplifying and isolating bacteria, DNA extraction, and molecular identification. The results showed that E. coli, as one of the main indicators of contamination, was observed in different samples and had the highest resistance to penicillin and amoxicillin antibiotics. Instead, they showed high sensitivity to carbapenem antibiotics, such as imipenem and meropenem. The overall conclusion of this study emphasizes the existence of defects in the production, purification, and packaging stages and the need for continuous monitoring of the quality of packaged waters. These findings indicate the importance of using microbial and molecular methods in monitoring water quality and the necessity of improving purification processes and managing antibiotic consumption to maintain public health.
