Clinical Isolates of Non-O157 Shiga Toxin-Producing Escherichia coli: Serotypes, Virulence Characteristics, and Molecular Profiles of Strains of the Same Serotype.

摘要

All human Shiga toxin-producing Escherichia coli (STEC) non-O157 strains (n = 56) isolated in Finland from 1990 to August 2000 were characterized for the O:H serotype, stx(1) and stx(2) genes, production of enterohemolysin, and sensitivity to 12 antimicrobial agents. Strains of the same serotype were genotyped by pulsed-field gel electrophoresis (PFGE) after XbaI restriction of total DNA. The 56 non-O157 isolates belonged to 29 serotypes. Two of the serotypes (O102:H7 and OX181:H49) have not previously been described as being associated with STEC infections in humans or isolated from animals. Thirty-four strains (61) within seven serotypes (O103:H2 14 isolates, O26:H11 6 isolates, O145:H28 4 isolates, O145:HNM 3 isolates, O15:HNM 3 isolates, OX174:H21 2 isolates, and O Rough:HNM 2 isolates) were represented by more than one isolate. Of these strains, O103:H2 isolates were divided into seven, O26:H11 isolates were divided into four, and the rest within a serotype were divided into two genotypes in PFGE. In PCR, 31 (55) of the 56 strains were positive for the stx(2) gene only and 24 strains (43) were positive for stx(1) only. One strain (O43:H2) carried both stx(1) and stx(2). Forty-two strains (75) produced enterohemolysin, and 39 strains (70) possessed the eae gene. Of the latter 39 strains, 36 (92) were enterohemolytic, whereas only 6 (35) of the 17 isolates lacking the eae gene were enterohemolytic (P < 0.001). The majority of the strains (44 strains, 79) were sensitive to all 12 antimicrobials tested. Of the 56 strains, 20 (36) were associated with small family outbreaks in nine families and 14 (25) were associated with recent travel abroad.