Clinical isolates of non-O157 Shiga toxin-producing Escherichia coli: serotypes, virulence characteristics, and molecular profiles of strains of the same serotype.
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.
Eklund
M
M
Laboratory of Enteric Pathogens, National Public Health Institute, FIN-00300 Helsinki, Finland.
Scheutz
F
F
Siitonen
A
A
D015373:Bacterial Typing Techniques; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D029968:Escherichia coli Proteins; D005387:Finland / Q000453:epidemiology; D006460:Hemolysin Proteins / Q000378:metabolism; D006801:Humans; D008826:Microbial Sensitivity Tests; D012703:Serotyping; D022622:Shiga Toxin 1 / Q000096:biosynthesis* / Q000235:genetics; D022641:Shiga Toxin 2 / Q000096:biosynthesis* / Q000235:genetics; D014774:Virulence
D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; D022622:Shiga Toxin 1; D022641:Shiga Toxin 2; C066219:enterohemolysin