Genotype of enterohemorrhagic Escherichia coli isolated in Heilongjiang province

Objective To study genotype of enterohemorrhagic Escherichia coli (EHEC) with three different subtyping methods, conduct molecular epidemiological analysis on EHEC detection in Heilongjiang and evaluate MLVA subtying effect on EHEC strains. Methods Seventy isolates of EHEC were analyzed by virulence gene identification, pulsed-field gel electrophoresis (PFGE) and multilocus variable-number tandem repeat analysis (MLVA). Results Twelve strains contained eaeA gene, seven strains contained hlyA gene, one strain contained stx1 and stx2 gene and 2 strains contained stx2 gene. Thirty five patterns in PFGE clusters were defined as strains that have same pattern by XbaⅠ digestion among 47 isolates, MLVA was performed by comparing the number of tandem repeats at seven loci, where seven loci showed 2 to 5 variations in the 10 isolates of EHEC O157, resulting in 8 MLVA types among the 10 isolates. Conclusion There was horizontal transmission of EHEC in household animal raising. Since null alleles existed in some strains were observed in 6 subtyping sites, more isolates are needed to conduct further study on subtyping effect of MLVA.