Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 48: 3293 - 3305. Published December 29, 2011.
Prevalence of pathogenic strains of Escherichia coli in urban streams in the equatorial region of Cameroon (Central Africa)
Mireille E. Nougang, Moïse Nola (*), Henriette Ateba Bessa, Blandine P. Tamatcho Kweyang, Olive V. Noah Ewoti and Luciane M. Moungang
University of Yaoundé 1, Faculty of Sciences, Laboratory of General Biology, P.O. Box 812, Yaoundé, Cameroon
(*): Corresponding e-mail: moise.nola@yahoo.comABSTRACT
Objective: Water quality from the Mfoundi River and some of its tributaries was studied by assessing some pathogenic strains of Escherichia coli and some physico-chemical variables (pH, electrical conductivity, dissolved oxygen, TDS (Total Dissolved Solids) and nitrites) that affected their distribution.
Methodology and results: Isolation of faecal coliforms was performed using membrane filtration technique. Identification of E. coli was done using biochemical tests. Pathogenic strains of E. coli were identified by their haemagglutination properties towards human red blood cells and serotyping using the Enteropathogenic E. coli (EPEC) antisera (Bio- Rad). Physico-chemical analyses were performed using standard methods. This study results revealed that the waters from the Mfoundi River and its tributaries were not safe according to the standards for water quality established by the World Health Organisation (WHO). This water basin harbours EPEC strains and their concentration sometimes attained 6 CFU/ml. It was also noted that the values of all the examined physico-chemical parameters exceeded WHO guidelines for recreational waters. The relationships between the bacterial abundance and physico-chemical parameters were of various magnitudes. The increase of the abundance of faecal coliforms, EPEC strains and the concentration of nitrites was concomitant in most cases (P<0.05). However, EPEC strains were rare in some sampling points. For the whole sampling periods, the greatest amounts of the faecal coliforms isolated were not always concomitant with those of EPEC.
Conclusion and application: The presence of EPEC strains in these water systems poses a health risk to several urban communities who rely on the river for their primary source for domestic needs. Further studies will probably yield much more information on the ratio between other pathogens and faecal indicator bacteria in the water. Risk assessments based on these ratios could be used for improving health-related standards
Key words: Prevalence, Pathogenic E. coli strains, river, water quality, physico-chemical
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