Immunomagnetic separation of Escherichia coli O157:H7 from environmental and wastewater in South Africa

Abstract

Recreational and drinking water supplies polluted with sewage have become an important source of E. coli O157:H7 infection. Immunomagnetic separation (IMS) has been extensively used for the isolation of E. coli O157:H7 from food and stool samples but not for samples such as wastewater. In this study the IMS method was used in combination with the E. coli O157:H7 selective media, immunoassays, biochemical tests and PCR, to assess the prevalence of E. coli O157:H7 in selected sewage and environmental water in South Africa. Environmental and wastewater were seeded with E. coli O157:H7 to determine the sensitivity and selectivity of the enrichment-IMS-selective agar method. Naturally occurring E. coli O157:H7 organisms were recovered from selected samples by means of IMS. The IMS concentrates were plated on three selective E. coli O157:H7 media. E. coli O157:H7 was detected in seeded sewage and river water samples with numbers as low as 1.2 cfu·m l-1. The IMS procedure was used to investigate the prevalence of E.

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