Clonal analysis of Escherichia coli strains isolated from pigs with post-weaning diarrhea by pulsed-field gel electrophoresis

The genetic diversity of 82 isolates of Escherichia coli recovered from pigs with post-weaning diarrhea was examined by restriction Fragment length poli morphism (RFLP) of chromosomal DNA digested with NotI and YbaI. The isolates were of serogroups O138, O139, O141, and O139 and possessed F4 and F18 fimbrial as well as LTI, STI, STII enterotoxin and shiga toxin 2e virulence markers. The restriction pattern profiles showed a high degree of polymorphism among isolates of different serotypes and a close relationship between strains belonging to the same serological group. In addition, some bacterial strains with identical virulence determinants exhibited distinct PFGE types. The results obtained showed that RFLP analysis is a powerful tool to reveal the clonal nature and genetic differences among E. coli strains responsible for diarrhea in weaned pigs. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All lights reserved.