Survival of Escherichia coli O157 in abattoir waste products

Aims: This study monitored survival and growth of Escherichia coli O157 in ovine and bovine abattoir waste.

Methods: Blood and gut contents were inoculated separately with cocktails of E. coli O157. Samples were stored aerophilically and microaerophilically at 5 degreesC, 15 degreesC and 30 degreesC to represent storage at different container depths and at extremes of UK ambient temperature.

Conclusions: Results showed survival of E. coli O157 was irrespective of oxygen content with no significant differences observed between aerophilic and microaerophilic environments. Numbers of E. coli O157 in ovine and bovine gut contents showed no change when stored at 5 degreesC and increased 1-2 log(10) at 15 degreesC and 30 degreesC in 28 h. In ovine and bovine blood, irrespective of storage temperature, there was a 0.5-2 log(10) reduction or no change in numbers except in ovine blood stored at 30 degreesC where the fall in numbers was followed by a 3 log(10) increase. In aged (stored at 4 degreesC for 18 h before spiking) bovine blood there was no significant change in numbers at 5 degreesC while at 15 degreesC there was 2 log(10) rise after 48 h. At 30 degreesC there was an initial 1 log(10) decrease in numbers followed by a 1 log(10) rise over the following 40 h.

Significance and impact of Study: Abattoir wastes may become contaminated from animals infected with Verocytotoxigenic E. coli O157 and in certain storage conditions these pathogens could significantly increase in numbers. There is need for care in abattoir waste disposal, not only for personnel subject to direct contact, but also in the prevention of cross contamination to adjacent land and water courses which could indirectly infect humans.