We investigated for virulence genes (stx1, stx2 and hlyA), serotypes and extended-spectrum β-lactamases (ESBLs) producing capacity in O157 and non-O157 Escherichia coli isolated from
producer-distributor bulk milk (PDBM). Fifteen different E. coli O-serogroups were observed
from the isolates (n=121). The prevalence of stx1 and stx2 genes among the E. coli isolates was
8.3% and 11.6% (n=121), respectively, while 5.8% harboured both stx1 and stx2. Four E. coli
isolates (3.3%) had ESBLs producing capacity, resisted multiple cephalosporins and aztreonam,
and carried stx genes. Cluster analysis using GTG5 finger printing revealed a diversity of E. coli
seropathotypes in PDBM which are known to be associated with human diarrhoeal diseases.
These results highlight a potential risk posed on human health by the consumption of PDBM
contaminated with pathogenic E. coli. A further quantitative risk assessment of the impact of
pathogenic E. coli contamination in PDBM on human health is therefore recommended.