| Contamination of Potable Water Distribution Systems by Multiantimicrobial-Resistant Enterohemorrhagic Escherichia coli Siya Ram, Poornima Vajpayee, and Rishi Shanker Environmental Microbiology Division, Industrial Toxicology Research Centre, Mahatma Gandhi Marg, Lucknow, India Abstract
Background: The contamination of processed or unprocessed drinking water by fecal coliform bacteria has been reported worldwide. Despite a high incidence of waterborne diseases, enterohemorrhagic Escherichia coli (EHEC) is an underacknowledged pathogen of concern to public health in India. Although the presence of EHEC is recorded in surface water resources of India, drinking water sources are yet to be investigated. Objectives: The goal of this study was to analyze potable water samples for the presence of virulence determinants of EHEC and to determine the sensitivity of the virulence determinants to antimicrobials. Methods: We enumerated coliform bacteria in potable water samples collected from six locations in Lucknow, a major city in northern India, using the most probable number method. E. coli (n = 81) , randomly isolated by membrane-filtration technique from four sites, were identified by biochemical characterization. E. coli were not detected in samples from two other sites. We screened 15 randomly selected isolates fromeachsite for virulence determinants of EHEC using polymerase chain reaction (PCR) . The isolates positive for virulence determinants (n = 18) were screened for sensitivity to 15 antimicrobials by the disk diffusion method. Results: Both stx1 and stx2 genes were present in 33.3% of isolates, whereas others possessed either stx1 (11.1%) or stx2 (55.6%) . eaeA,hlyA, and chuA genes were present in 100, 23.3, and 16.7% of isolates, respectively.Resistance to multiple antimicrobials was observed in potential EHEC. Conclusions: The occurrence of multiantimicrobial-resistantEHECin potable water is an important health concern because of the risk of waterborne outbreaks. Key words: drinking water, enterohemorrhagic Escherichia coli, multiantimicrobial resistant, virulence determinants. Environ Health Perspect 116:448–452 (2008) . doi:10.1289/ehp.10809 available via http://dx.doi.org/ [Online 21 December 2007]
Address correspondence to R. Shanker, Environmental Microbiology Division, Industrial Toxicology Research Centre, Post Box 80, Mahatma Gandhi Marg, Lucknow-226001, U.P., India. Telephone: 91-0522-2613786, ext. 237. Fax: 91-0522-2611547. E-mail: rishishanker1@rediffmail.com We thank C.M. Gupta, Director, ITRC, Lucknow, for providing the necessary facilities for this study. This work was supported by CSIR (Council of Scientific and Industrial Research) Network Project SMM-05. S.R. received financial support (Senior Research Fellowship) from the CSIR, and P.V. received financial assistance (Young Scientist) from the Department of Science and Technology. ITRC manuscript # 2574. The authors declare they have no competing financial interests. Received 28 August 2007 ; accepted 21 December 2007.
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