Virulence properties of Escherichia coli isolated from Australian dairy powder factory environments

A total of 298 environmental samples from 5 separate dairy powder factories (A–E) were analysed for the presence of Escherichia coli. E. coli was isolated from 80 of these samples to obtain 359 isolates. These isolates were tested for the presence of 12 virulence genes associated with enteropathogenic E. coli (EPEC), atypical EPEC, Shiga toxin (Stx)-producing E. coli (STEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC) and enteroaggregative E. coli (EAEC). A total of 4 isolates obtained from two different sampling points at Factory C were positive for the astA gene, indicative of EAEC. A further 2 isolates from one sample from Factory C were positive for the presence of eaeA and escV genes, indicative of atypical EPEC. No virulence genes were detected in the remaining 353 isolates. While E. coli was present within the environment of dairy powder processing factories the carriage of potential virulence genes was low.