Survival of Escherichia coli O157:H7 in waters from lakes, rivers, puddles and animal-drinking troughs.

ABSTRACT

Survival of Escherichia coli O157H7 in surface waters may increase the potential for dissipation of the organism to facilitate cycles of livestock re-infection and lead to human infection. Although previous studies have monitored survival of the organism in a range of surface waters, there is limited information on the influence of physico-chemical characteristics on persistence. Microcosms of four different surface water types (n=31) from the UK were inoculated with E. coli O157H7 and incubated at 10 degrees C. The water types studied were lake, puddle, river, and animal-drinking trough waters. Numbers of E. coli O157H7 declined over time in all waters, although cells were still detected in 45% of non-sterile samples after 2 months. Persistence of E. coli O157H7 was enhanced by water aeration and by prior sterilisation; however there was no correlation between water chemistry and mean E. coli O157H7 die-off times or rates in any water type. Survival of the pathogen was better in lake and puddle waters than in river or drinking trough waters. Further studies are needed to establish the key water quality factors that regulate pathogen survival.