Impact of Some Ecological Factors on Fecal Contamination of Drinking Water by Diarrheagenic Antibiotic-Resistant Escherichia coli in Zagazig City, Egypt

Our plain-English summary of Impact of Some Ecological Factors on Fecal Contamination of Drinking Water by Diarrheagenic Antibiotic-Resistant Escherichia coli in Zagazig City, Egypt, by A.E. Fakhr, M.K. Gohar, A.H. Atta (International Journal of Microbiology, 2016).

The study

• Authors: A.E. Fakhr, M.K. Gohar, A.H. Atta
• Journal: International Journal of Microbiology
• Published: 2016;2016:6240703
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Fecal contamination of drinking water is a major health problem which accounts for many cases of diarrhea mainly in infants and foreigners. This contamination is a complex interaction of many parameters. Antibiotic resistance among bacterial isolates complicates the problem. The study was done to identify fecal contamination of drinking water by Diarrheagenic Antibiotic-Resistant Escherichia coli in Zagazig city and to trace reasons for such contamination, three hundred potable water samples were investigated for E. coli existence. Locations of E. coli positive samples were investigated in relation to population density, water source, and type of water pipe. Sixteen E. coli strains were isolated. Antibiotic sensitivity was done and enterotoxigenic, enteropathogenic, and enterohaemorrhagic virulence genes were investigated by PCR. Probability of fecal contamination correlated with higher population density, with increased distance from Zagazig water plant, and with asbestos cement water pipes. Resistance to at least one antimicrobial drug was found in all isolates. Virulence genes were detected in a rate of 26.27%, 13.13%, 20%, 6.67%, and 33.33% for LT, ST, stx1, stx2, and eae genes, respectively. This relatively high frequency of fecal contamination points towards the high risk of developing diarrhea by antibiotic resistant DEC in low socioeconomic communities particularly with old fashion distribution systems.

In plain English

This study tested drinking water for bacteria. It did not study asbestos-related disease. In 2011 the authors collected 300 tap-water samples across the three districts of Zagazig, Egypt, plus samples from the main water plant and wells taken before the water entered the pipe network. Source samples had no coliform bacteria. Coliforms were found in 12% of tap samples and E. coli in 16 (5.33%): 9 in the 1st district, 7 in the 2nd and none in the 3rd. Eleven of the 16 E. coli came from the most densely populated areas, and all came from areas away from the main water plant. On the pipe map, 10 positive samples lay in areas with asbestos cement pipes, 2 in areas with PVC pipes and 4 in areas where pipe type was unclear. Contamination rose in spring. All 16 isolates resisted at least one antibiotic and 10 resisted three or more. Eight carried at least one diarrhea-related gene. The authors concluded that replacing old pipes or building another plant should be investigated. They noted they had too few isolates to judge how common these genes are.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Cross-sectional environmental survey: tap-water samples cultured for coliforms and E. coli, with antibiotic testing and PCR for virulence genes, and positive sample locations compared on maps
• Who was studied: 300 tap-water samples from the 3 districts of Zagazig city, Egypt, in 2011 (90 from the 1st district, 120 from the 2nd and 90 from the 3rd), plus samples from the main water plant and underground wells before distribution
• Exposure: Fecal contamination of drinking water by E. coli, examined in relation to population density, water source and pipe material (asbestos cement versus PVC). Asbestos appears only as a pipe material; asbestos itself was not measured.
• Main results:
  • All samples taken before the water entered the distribution system had no coliforms.
  • Across all 300 tap samples, 12% had coliforms and 5.33% (16 samples) had E. coli.
  • 1st district: 20 samples (22.2%) had coliforms and 9 (10.0%) had E. coli. 2nd district: 16 (13.3%) had coliforms and 7 (5.83%) had E. coli. 3rd district: no coliforms.
  • Coliforms (p = 0.05) and E. coli (p = 0.03) were more common in spring months, with a peak in March.
  • 11 of the 16 E. coli (68.75%) came from areas with the highest population density.
  • All E. coli isolates came from areas away from the main water plant.
  • By map location, 10 E. coli-positive samples fell in areas with asbestos cement pipes, 2 in areas with PVC pipes and 4 in areas with unclear pipe type.
  • All 16 E. coli isolates resisted at least one antibiotic, and 10 of 16 (62.5%) resisted three or more.
  • Resistance was highest to cefotaxime and tetracycline (62.5% of isolates each), followed by ampicillin (50%).
  • 8 isolates (50.0%) carried at least one virulence gene.
  • Gene counts: 4 isolates had the LT gene (2 of them also had ST), 3 had stx1 (1 of them also had stx2), and 5 had the eae A gene.
• The authors' conclusion: The authors concluded that wider rational use of antibiotics is urgently needed, and that renewing the city's old water pipes or building another water plant on the eastern side of the city should be investigated as ways to reduce fecal contamination.
• Limitations the authors state:
  • There were too few isolates to judge properly how common the virulence genes are.
  • Because the pipe network is continuous, the authors could not tell which areas were supplied by each well or only by the main plant.
  • Whether the isolates can actually cause diarrheal illness in people could not be established.
  • The membrane filtration method may fail to recover stressed or injured coliforms.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement.

Related studies

• Escherichia coli cells penetrated by chrysotile fibers are transformed to antibiotic resistance by incorporation of exogenous plasmid DNA — N. Yoshida, K. Kodama, et al. (2002)
• Chemical contamination of California drinking water — H.H. Russell, R.J. Jackson, et al. (1987)
• Chrysotile asbestos fibers mediate transformation of Escherichia coli by exogenous plasmid DNA — N. Yoshida, T. Ikeda, et al. (2001)
• Chestnut bur-shaped aggregates of chrysotile particles enable inoculation of Escherichia coli cells with plasmid DNA — N. Yoshida, Y. Saeki (2004)
• Mutagenesis of Escherichia coli (CSH50) by asbestos — M.G. Cleveland (1984)
• Asbestos-contaminated drinking water: its impact on household air — J.S. Webber, S. Syrotynski, et al. (1988)

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