Escherichia Coli and Fecal Coliforms in Freshwater and Estuarine Sediments

It has been known for some time that substantial populations of fecal coliforms and E. coli are harbored in freshwater bottom sediments, bank soils, and beach sands. However, the relative importance of sediments as bacterial habitats and as a source of water-borne fecal coliforms and E. coli has not been recognized until recently, when a large number of publications have shown that in many cases the resuspension of sediment, rather then runoff from surrounding lands, can create elevated E. coli concentrations in water. This review is an attempt to develop the first comprehensive single source of existing information about fecal coliforms and E.coli in sediments and adjacent soils and to outline the knowledge gaps and research needs. The authors summarize available information on variability and environmental correlations of E.coli and FC concentrations in sediments, genetic diversity of E.coli in sediments, survival of E. coli and FC in sediments, release with resuspended sediment and settling of E. coli and FC, modeling of sediment effects on fate and transport of E. coli in surface waters, and implications for monitoring and management of microbiological water quality. The demonstrated role of pathogenic E. coli strains in food and water quality challenges reinforces the need in better understanding ecological and hydrological factors that affect functioning of sediments as E. coli reservoirs.