An investigation into the pathogenic properties of Escherichia coli strains BLR, BL21, DH5alpha and EQ1
2000
Chart, H. | Smith, H.R. | La Ragione, R.M. | Woodward, M.J.
Aims: To examine Escherichia coli strains EQ1, DH5alpha, BLR and BL21 for known pathogenic mechanisms. Methods and Results: Using specific DNA probes, the strains were shown not to carry the genes encoding invasion, various adhesion phenotypes or expression of a range of enterotoxins. The strains were unable to express long-chain lipopolysaccharide and were susceptible to the effects of serum complement. Using a BALB/c mouse model, the strains were shown to be unable to survive in selected tissues or to persist in the mouse gut. Using a chick model, strains EQ1, BLR and BL21 invaded livers but not spleens; only strain EQ1 persisted in the chick gut. In Merino sheep, only strain EQ1 was detected 6 d post-infection. Conclusions: Escherichia coli strains EQ1, DH5alpha, BLR and BL21 did not carry the well-recognized pathogenic mechanisms required by strains of E. coli causing the majority of enteric infections. Significance and Impact of the Study: Escherichia coli strains EQ1, DH5alpha, BLR and BL21 were considered to be non-pathogenic and unlikely to survive in host tissues and cause disease.
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