Absence of Escherichia coli phylogenetic group B2 strains in humans and domesticated animals from Jeonnam Province, Republic of Korea

Abstract

Multiplex PCR analyses of DNAs from genotypically unique Escherichia coli strains isolated from the feces of 138 humans and 376 domesticated animals from Jeonnam Province, South Korea, performed using primers specific for the chuA and yjaA genes and an unknown DNA fragment, TSPE4.C2, indicated that none of the strains belonged to E. coli phylogenetic group B2. In contrast, phylogenetic group B2 strains were detected in about 17% (8 of 48) of isolates from feces of 24 wild geese and in 3% (3 of 96) of isolates obtained from the Yeongsan River in Jeonnam Province, South Korea. The distribution of E. coli strains in phylogenetic groups A, B1, and D varied depending on the host examined, and there was no apparent seasonal variation in the distribution of strains in phylogenetic groups among the Yeongsan River isolates. The distribution of four virulence genes (eaeA, hlyA, stx(1), and stx(2)) in isolates was also examined by using multiplex PCR. Virulence genes were detected in about 5% (38 of 707) of the total group of unique strains examined, with 24, 13, 13, and 9 strains containing hlyA, eaeA, stx(2), and stx(1), respectively. The virulence genes were most frequently present in phylogenetic group B1 strains isolated from beef cattle. Taken together, results of these studies indicate that E. coli strains in phylogenetic group B2 were rarely found in humans and domesticated animals in Jeonnam Province, South Korea, and that the majority of strains containing virulence genes belonged to phylogenetic group B1 and were isolated from beef cattle. Results of this study also suggest that the relationship between the presence and types of virulence genes and phylogenetic groupings may differ among geographically distinct E. coli populations.

FIG. 1.

Distribution of phylogenetic groups among E. coli isolates obtained from humans and domesticated animals: open bar, group A; diagonally hatched bar, group B1; black bar, group B2; cross-hatched bar, group D.

FIG. 2.

Seasonal variations in phylogenetic group distribution among E. coli isolates obtained from the Yeongsan River, Jeonnam province, South Korea: open bar, group A; diagonally hatched bar, group B1; black bar, group B2; cross-hatched bar, group D.

FIG. 3.

Distribution of virulence genes among phylogenetic groups of E. coli obtained from humans and domesticated animals: black bar, eaeA; diagonally hatched bar, hlyA; open bar, stx₁; cross-hatched bar, stx₂. Numbers of isolates are given in parentheses.

FIG. 4.

Genetic relatedness of E. coli strains possessing virulence genes. The dendrogram was generated from HFERP DNA fingerprints using Pearson's product-moment correlation coefficient and the unweighted pair group method with arithmetic means clustering method.

FIG. 5.

Phylogenetic grouping analysis of HFERP DNA fingerprints using MANOVA: green, group A; red, group B1; purple, group D HFERP DNA fingerprints from E. coli strains obtained from animal and human sources were numerically converted to binary band-matching character tables and analyzed by MANOVA accounting for the covariance structure.