Bharath J, Mosodeen M, Motilal S, Sandy S, Sharma S, Tessaro T, Thomas K, Umamaheswaran M, Simeon D, Adesiyun A A
School of Medicine, Faculty of Medical Sciences, University of the West Indies, St. Augustine, Trinidad and Tobago.
Int J Food Microbiol. 2003 Feb 25;81(1):53-62. doi: 10.1016/s0168-1605(02)00193-9.
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.
开展了一项横断面研究，以确定特立尼达岛销售的国产和进口瓶装水的微生物质量。这些瓶装水购自特立尼达岛的六个地理区域，代表了整个岛屿。采用2%的精确率和5%的I型错误率，确定样本量为344瓶水。采用膜过滤技术，分别在m-远藤琼脂和m-FC琼脂上培养，以检测总大肠菌群和耐热大肠菌群。在营养琼脂上测定需氧平板计数（APC）；在麦康凯琼脂上检测铜绿假单胞菌，在伊红美蓝（EMB）上分离大肠杆菌，并用标准方法检测沙门氏菌属。在检测的344份水样中，分别有262份（76.2%）和82份（23.8%）是国产和进口品牌。344份样本中有18份（5.2%）含有大肠菌群，每100毫升平均计数为0.88±6.38个大肠菌群，而5份（1.5%）样本含有大肠杆菌。国产瓶装水中总大肠菌群的患病率为6.9%（262份中的18份），而进口品牌中检测到的患病率为0.0%（82份中的0份）。差异具有统计学意义（p=0.004）。同样，国产瓶装水中需氧菌的患病率（33.6%）显著高于进口品牌（14.8%）（p=0.001）。总水样中有26份（7.6%）含有假单胞菌属，但所有样本的耐热大肠菌群和沙门氏菌属均为阴性。得出的结论是，根据饮用水中大肠菌群推荐的零容忍度，特立尼达岛销售的5%的瓶装水可能被认为不适于人类消费。
