Genetic diversity of Escherichia coli isolated from commercial swine farms revealed by enterobacterial repetitive intergenic consensus

Abstract

The objective of this study was to use enterobacterial repetitive intergenic consensus PCR (ERIC-PCR)
and repetitive extragenic palindrome PCR (REP-PCR) for the analysis of genetic diversity among
Escherichia coli strains isolated from commercial swine farms in Sichuan province of China. Thirty four
strains of E. coli were selected by selective medium and conventional biochemical test from fresh stool
samples of swines in five farms in Sichuan province. The isolates were identified by 160 kinds of E. coli
O serums. The results show that 30 strains were determined among 34 E. coli isolates, 12 kinds of O
serogroups were obtained on the basis of the agglutination test. The predominant types are O23, O 113
and O120, representing 35.4%. Furthermore, the genotypes and phylogenetic relationship of all isolates
were analysed by Enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) and repetitive
extragenic palindrome PCR (REP-PCR), 34 E. coli isolates were clustered to 19 ERIC-PCR genotypes
and 13 REP-PCR genotypes. The isolates from the same farm or sharing the same serotyping showed
different genotype. And the isolates which could not be serotyped were genotyped by ERIC-PCR and
REP-PCR. The analysis of genetic type and original source revealed that isolates from different farms
had different genetic types. The subtypes of E. coli are also different within a single farm. Genetic
variability with E. coli strains isolated from swine farms in China has been demonstrated. The presence
of ERIC-PCR and REP-PCR sequences in the genome of E. coli was confirmed. ERIC-PCR and REP-PCR
techniques are more rapid methods for molecular typing of E. coli strain. They are also useful methods
for diversity survey of E. coli and the two methods analyzes genetic diversity of E. coli isolated in
Sichuan of China.