Study of the Microbiological Quality of Bulgarian Bottled Water in Terms of Its Contamination with Pseudomonas Aeruginosa.

BACKGROUND: Due to the widespread use of bottled water, it is important from a hygienic point of view to ensure that these products have good quality and meet the requirements set out in regulations.

METHODS AND RESULTS: In the period 2000-2013, a large-scale study (2,500 samples) was carried out on the quality of Bulgarian bottled water as per the microbiological parameters laid down in the European and Bulgarian legislation. Standard microbiological methods were applied. There is strong evidence that the most frequently isolated contaminant in these products was Pseudomonas aeruginosa. This agent was found in 274 samples out of a total of 2,500 analysed bottled waters. Because of the absolute prohibition of the presence of this microorganism in the finished product, the manufacturers should not allow their products with compromised quality to reach the market. They are obliged to check the quality of each batch by conducting an internal monitoring of production. When any inconsistencies are established in microbiological parameters, the producers must detect the critical point and apply more effective decontamination measures of the bottling lines. Given the importance of this fact for the health of consumers, the study also included determination of the antimicrobial resistance of P. aeruginosa strains isolated from Bulgarian bottled water. Ten strains of P. aeruginosa, isolated from bottled water and other water habitats in the environment, were tested for the effect of 13 antimicrobial agents by applying the Kirby-Bauer's method.

CONCLUSIONS: The investigation found that Pseudomonas aeruginosa strains isolated from bottled water are sensitive to Ceftazidime, Amikacin, Ciprofloxacin, and Cefepime and one of them is resistant to Meropenem and Piperacillin. Another important conclusion is that there is no specific behaviour of P. aeruginosa strains originating from different sources to the test antimicrobials. The authors consider that drinking tap water is perhaps a more appropriate way for newborns, infants, elderly, and people with compromised immunity to satisfy thirst than using bottled water.