Detection of Escherichia coli, Salmonella species, and Vibrio cholerae in tap water and bottled drinking water in Isfahan, Iran

Momtaz et al. BMC Public Health 2013, 13:556 http://www.biomedcentral.com/1471-2458/13/556 RESEARCH ARTICLE Open Access Detection of Escherichia coli, Salmonella species, and Vibrio cholerae in tap water and bottled drinking water in Isfahan, Iran Hassan Momtaz1*, Farhad Safarpoor Dehkordi2, Ebrahim Rahimi3 and Amin Asgarifar4 Abstract Background: The quality of drinking water has an important role in human infection and disease. This study was aimed at comparing polymerase chain reaction and culture in detecting Escherichia coli, Salmonella species and Vibrio cholera in tape water and bottled drinking water in various seasons in Isfahan province, Iran. Methods: A total of 448 water samples from tap water and bottled mineral water were taken over 6 months, from July 2010 to December 2010, and after filtration, samples were examined by culture and polymerase chain reaction methods for detection of Escherichia coli, Salmonella species, and Vibrio cholerae. Results: The culture method showed that 34 (7.58%), 4 (0.89%) and 3 (0.66%) of all 448 water samples were positive for Escherichia coli, Salmonella species, and Vibrio cholera, respectively. The uidA gene from Escherichia coli, IpaB gene from Salmonella species, and epsM gene from Vibrio cholera were detected in 38 (26.38%), 5 (3.47%), and 3 (2.08%) of 144 tap-water samples, respectively. Escherichia coli was detected in 8 (2.63%) of 304 samples of bottled drinking water from 5 companies. The water of southern part of Isfahan and company 5 had the highest prevalence of bacteria. The Escherichia coli water contamination was significantly higher (P < 0.05) in the hot seasons (July-August) than cold (November-December) seasons and in company 5 than other companies. There were significant differences (P < 0.05) for the prevalence of bacteria between the tap waters of southern part and tap waters of central part of Isfahan. Conclusions: This study showed that the polymerase chain reaction assays can be an extremely accurate, fast, safe, sensitive and specific approach to monitor drinking water quality from purification facilities and bottled water companies. Also, our study confirmed the presence of Escherichia coli, Salmonella species, and Vibrio cholerae as water-borne pathogens in tap water and bottled drinking water of Isfahan, Iran. The present study showed the important public health problem in Isfahan, Iran. Keywords: Escherichia coli, Salmonella species, Vibrio cholerae, Water, PCR, Iran Background Despite modern techniques for disinfection, sanitation, and water purification, waterborne diseases still threaten human health. For all living organisms, water is the most vital and important matter for survival [1]. Today, in many under-developed and even developing countries, waterborne diseases still pose a major risk in drinking water. To the authors’ knowledge, the safety of commercial drinking * Correspondence: 1 Department of Microbiology, College of Veterinary Medicine, ShahreKord Branch, Islamic Azad University, P.O. Box: 166, ShahreKord, Iran Full list of author information is available at the end of the article water is generally dependent on the disinfection of natural water used at the factory. Sewage and pesticides can easily contaminate drinking water supplies. Therefore, monitoring the microbiological quality of drinking water is essential. Studies showed that ingestion of water contaminated with coliforms such as Escherichia coli (E. coli), Salmonella species (Salmonella spp.), and Vibrio cholerae (V. cholerae) can create serious complications including diarrhea, enteritis, and even death, leading to high economic losses [2-6]. Salmonella spp., V. cholerae, and E. coli are classified as zoonotic agents. These bacteria are © 2013 Momtaz et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Momtaz et al. BMC Public Health 2013, 13:556 http://www.biomedcentral.com/1471-2458/13/556 found almost everywhere. Humans, animals, and sewage can be sources of these bacteria. Contaminated water plays an important role in transmission of bacteria to humans. Using accurate, fast, safe, reliable, sensitive, and specific diagnostic methods in water purification facilities can have a decisive impact on ensuring the absence of microbial pathogens in tap water and bottled drinking water. Among all diagnostic techniques such as culture, serology, and molecular methods, the last one is the fastest [7]. Molecular methods have high sensitivity [8], specificity [9] and safety [10]. Nonetheless, culture methods remain popular because of their ease and simplicity. Polymerase Chain Reaction (PCR) is one of the most widely used molecular methods for detection of a wide variety of microorganism in various clinical samples. The PCR assays have been developed for detection of Salmonella spp., V. cholerae, and E. coli in a wide variety of sample types such as water [4], food [11-13], milk [14,15], and stool [16-18]. The purposes of this study were to detect Salmonella spp., V. cholerae, and E. coli in tap water and bottled drinking water in Isfahan, Iran, and to introduce PCR assays as an approach for detection of these bacteria in water samples. Methods Sample collection Isfahan province -with population of 4,800,000 and an area of 291,107,044 square kilometers - is the second big province of Iran and is located in central part of Iran among Iran’s central mountains and eastern hillside of the Zagros Mountains at the margin of Zayanderood River. The drinking water of this province is supplied from Zayande-rood River which is considered as surface water. It is probable that this water is contaminated with industrial and urban sewerage at the margin of this river. To our knowledge, except refinement (filtering and chlorine dissipate), there are no hygienic activities (for example radiation on drinking water) for control the quality of drinking water in Isfahan. Also, this river is the only watercourse of companies producing bottled drinking water in this province. Therefore, one of the sources of microbial contamination (such as Escherichia coli, Salmonella spp., and Vibrio cholerae) in this area is water. Besides, most of hospitals, especially at the central part of Isfahan, use from this water and it is important to free from any pathogens. In this study, total of 448 tap-water and bottled drinking water were examined over a period of 6 months, from July 2010 to December 2010. Totally, 144 tap-water samples were collected from four different geographical regions of Isfahan province. For each region, 36 samples were collected in Page 2 of 7 1000 mL glass bottles containing 0.5 g of sodium thiosulphate for dechlorination of the water. Also, 304 bottled drinking water wer (...truncated)