Q-252. Comparison of Bacterial Endotoxin Concentration (LPS) and Heterotrophic Plate Count for Microbial Quality of Commercial Bottled Water

E. L. Negron-Martinez, J. Norat Ramirez, J. Paredes Araud;
Univ. of Puerto Rico-Med. Sci. Campus, San Juan, PR.

Consumers increasingly use bottled water and home water treatment systems to avoid direct tap water. According to the International Bottled Water Association (IBWA), an industry trade group, 5 billion gallons of bottled water were consumed by North Americans in 2001. The principal aim of this study was to assess the microbial quality of in-house and imported bottled water for human consumption, by measurement and comparison of the concentration of bacterial endotoxin and standard cultivable methods of indicator microorganisms, specifically, heterotrophic and fecal coliform plate counts. Dilutions of 19 different lots, selected at random, of 5 different house and imported commercial bottled water brands were tested. Two different culture media, R2A and HPC were used to measure the heterotrophic plate counts using the membrane filtration method. The Standard Limulus Amebocyte Lysate test, kinetic turbidimetric assay, was used to measure the endotoxin concentrations. The minimum endotoxin concentration in 19 water samples was 0.00397 EU/mL, while the maximum was 71.8 EU/mL. The minimum bacterial count showed no growth, while the maximum was 3,500 CFU/mL. There was no statistically significant difference between the results of the log bacterial counts measured using the R2A and HPC cultivable methods, p>0.05. Spearman analysis showed a positive statistically significant association between log endotoxin concentration and heterotrophic plate count of bottled water, p<0.05. We suggest that measurement of Gram-negative bacterial endotoxin may be used as a rapid way of determining bacteriological water quality of bottled water for human consumption. Although bacterial growth was not detected in some water samples endotoxin was present, which strengthen our findings.