Microbial quality of domestic and imported brands of bottled water in Trinidad.

A cross-sectional study was conducted to determine the microbial quality of domestic and imported brands of bottled water available in Trinidad, purchased from six geographical regions in Trinidad, and representing the whole island. A sample size of 344 bottles of water was determined by using a precision rate of 2% and a Type 1 error of 5%. The membrane filter technique was used with cultures grown on m-Endo agar and m-FC agar for total coliforms and thermotolerant coliforms, respectively. Aerobic plate count (APC) was determined on nutrient agar; Pseudomonas aeruginosa was detected on MacConkey agar, Escherichia coli was isolated on eosin methylene blue (EMB) and Salmonella spp. was assayed by using standard methods. Of the 344 water samples tested, 262 (76.2%) and 82 (23.8%) were domestic and imported brands, respectively. Eighteen (5.2%) of the 344 samples contained coliforms with a mean count of 0.88+/-6.38 coliforms per 100 ml, while 5 (1.5%) samples contained E. coli. The prevalence of total coliforms in domestic brands of bottled water was 6.9% (18 of 262) as compared with 0.0% (0 of 82) detected in imported brands. The difference was statistically significant (p=0.004). Similarly, the prevalence of aerobic bacteria in domestic brands of bottled water (33.6%) was significantly higher (p=0.001) than was found in imported brands (14.8%). Twenty-six (7.6%) of the total samples of water contained Pseudomonas species, but all were negative for thermotolerant coliforms and Salmonella spp. It was concluded that based on the recommended zero tolerance for coliforms in potable water, 5% of bottled water sold in Trinidad could be considered unfit for human consumption.

Microbial quality of local and imported brands of bottled water in Trinidad [abstract]

A cross-sectional study was conducted to determine the microbial quality of local and imported brands of bottled water available in supermarkets, groceries, and parlours in Trinidad. A sample size of 344 bottles of water was determined by using a precision rate of 2 percent and a Type 1 error of 5 percent. These bottles were purchased from six geographical regions in Trinidad which represented the whole island. The membrane filter technique was used with cultures made on endo agar and Fc agar for total coliforms and faecal coliforms, respectively. Total aerobic plate count (TAPC) was determined on nutrient agar, Pseudomonas aeruginosa and Salmonella spp were assayed using standard methods. Of the 344 water samples tested, 239 (69.5 percent) and 105 (30.5 percent) were local brands and imported brands, respectively. Eighteen (5.2 percent) of 344 samples were contaminated by coliforms with a mean count of 0.88 2 ñ 6.38 coliforms per 100 ml while 5(1.5 percent) samples were contained Escherichia coli. The prevalence of total coliforms in local brands of bottled water was 7.5 percent (18 of 239) compared with 0.0 percent (0 of 105) detected in imported brands. The difference was statistically significant (p= 0.004). Similarly, the prevalence of aerobic bacteria in local brands of bottled water (34.7 percent) was significantly (p= 0.001) higher than that found in imported brands (17.1 percent). Among local brands, the prevalence of total coliforms ranged from 0.0 percent to 13.8 percent but the difference was not statistically significant (p= 0.121). However, the prevalence of aerobic bacteria among these local brands ranged from 5.0 percent to 88.5 percent and the difference was significant (p< 0.0001). All water samples tested were negative for faecal coliforms, Salmonella spp and P aeruginosa. It was concluded that based on the recommended zero tolerance for coliforms in potable water, 5 percent of bottled water sold in Trinidad could be considered unfit for human consumption. The need to implement national standards for bottled water in Trinidad cannot be over-emphasized. (AU)