The colicinogenic properties of porcine Escherichia coli strains

The colicine production of 789 porcine E. coli strains was investigated in temperatures of 37°G and 40 °C respectively. The results are expressed in tabular form. It was found that of 435 strains isolated from an equal number of colibacillosis cases about 60 % were coli-cinogenic, 52.4 % producing colicine in both incubation temperatures used, whereas of 354 strains isolated in the intestinal content of healthy pigs only 17 % produced colicine. The inhibitive zone formed by strains belonging to O-groups 141ab and 141ac was significantly larger than that formed by other serological groups. It was found that in nearly all colicinogenic strains the inhibitive zone was larger when incubated at 40 °C than at 37 °C. The higher incubation temperature is recommended in determination of colicine production of porcine E. coli strains.