Detection of Virulence Genes and Biofilm Forming Capacity of Diarrheagenic E. coli Isolated from Different Water Sources

Sadaf Tariq,Mika Sillanpaa,Sobia Tabassum,Wahidah H Al-Qahtani,Shafaqat Ali,Sadia Aslam

doi:10.3390/coatings11121544

Abstract

Diarrheagenic Escherichia coli (DEC) are associated with frequent incidences of waterborne infections and pose health risk to individuals who contact water for domestic or recreational uses. Detection of DEC pathotypes in drinking water can be used as an indicator of fecal contamination. This study aimed to investigate the occurrence of DEC pathotypes and their capacity to form biofilms in drinking water samples collected from different water sources. In this study, PCR analysis was used to determine the occurrence of four clinically significant virulence genes of diarrheagenic E. coli, eaeA (Enteropathogenic E. coli), stx1, stx2 (Enterohemorrhagic E. coli) and sth (Enterotoxigenic E. coli), in drinking water samples (n = 35) by using specific primers and conditions. PCR amplicons were visualized by using agarose gel electrophoresis. A total of 12/35 (34%) samples were detected as positive for at least one of the four DEC virulence genes and 11/12 (91%) E. coli isolates harbored virulence gene while 1/12 (8%) E. coli isolates harbored none. The eaeA and sth genes were the most detected genes (75%), while stx1 and stx2 genes were least detected genes (66%). Biofilm assay confirmed that ETEC pathotypes can cause damage in enteric walls by attaching and effacing to persist diarrheal conditions. This study indicated that drinking water of different sources is contaminated with potential DEC pathotypes and it can be a source of diarrheal diseases. The amplification of four virulence genes associated with DEC pathotypes (EPEC, EHEC and ETEC) in drinking water demonstrates that potentially virulent DEC pathotypes are distributed in water sources and may be a cause of health concern. There is, therefore, an urgent need to monitor DEC pathotypes in drinking water.

Highlights

In order to ensure good health, the availability of safe and good quality water is very essential [1]
Drinking water samples were collected from different water sources: ten samples were collected from tank water, five samples were collected from industries, five samples were infused water, three samples were collected from standing water areas, five samples were collected from wells and seven samples were collected from tap labeled as 1–35, respectively
The frequencies of pathotypes were as follows: enteropathogenic E. coli (EPEC) (75%), enterohemorrhagic E. coli (EHEC) (66%) and enterotoxigenic E. coli (ETEC) (75%). These findings demonstrated that the rate of prevalence of EPEC and ETEC is very high among Diarrheagenic Escherichia coli (DEC) pathotypes isolated from drinking water sources

Summary

Introduction

In order to ensure good health, the availability of safe and good quality water is very essential [1]. Ground water is the sole elementary source of drinking water supply, which may contain several pathogens, viruses, bacteria and protozoa, causing 2.5 million deaths from enteric diarrheal diseases annually [3,4]. Diarrheal and other gastrointestinal illnesses are common infections among infants and children in developing countries [5]. E. coli can survive in drinking water for 4 to 12 weeks, depending upon various environmental factors. According to its biological significance, E. coli live safely in the intestine as harmless commensal [9] and pathogenic strains of bacteria cause intestinal and extra-intestinal infections both in healthy and immunocompromised individuals [2,10]

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