Risk Assessment of Heterotrophic Bacteria from Bottled Mineral Water Consumed in Syria

Four hundred and thirty samples of bottled mineral water belonging to ten different local and imported brands collected from the Syrian market have been analyzed bacteriologically. Heterotrophic plate count (HPC) was determined using R2A agar culture medium and incubating at 22οC for 5–7 days. Pseudomonads and Aeromonads members were selectively investigated and identified biochemically. Around 70 % of the imported water samples exhibited HPC counts more than 100 cfu/ml versus 13 % for local ones. Risk assessment of the heterotrophic bacteria revealed that 53.49% of the strains showed resistance to one or two of the twenty antibiotics tested and the highest resistance was found against nalidixic acid, novobiocin, ampicillin, streptomycin, imipenem and ampicillin/sulbactam. The majority of Pseudomonas spp. and Aeromonas spp. strains were found to be resistant to nalidixic acid, trimethoprim/ sulfamethoxazole, ampicillin, and novobiocin. Pseudomonas spp. showed also high resistance to tetracycline, imipenem, ceftazidime, amikacin, erythromycin and carbencillin. The most effective antibiotics against Pseudomonas spp. were ciprofloxacin, gentamicin, aztreonam, colistin, kanamycin and ceftriaxone. However, the following antibiotics showed complete activity against Aeromonas spp. amikacin, ceftazidime, ceftriaxone, ciprofloxacin and gentamicin. The complete activity was also seen for aztreonam, chloramphenicol and gentamicin against other HPC bacteria. Strains with multiple antibiotic resistance (MAR) represented 60.18% of all isolates and the most resistant organism belonged to the genus Pseudomonas followed by Aeromonas strains. The high load of heterotrophic bacteria with relatively high counts of opportunists such as Pseudomonads and Aeromonads in the studied mineral bottled water represents hygienic and quality challenge for this ready-to-consume commodity. Moreover, multiple antibiotic resistance detected among these bacteria might pose health significances, at least to some defined sensitive individuals, and should be considered properly.