Characteristics of O157 versus non-O157 Shiga toxin-producing Escherichia coli infections in Minnesota, 2000-2006.
BACKGROUND
Escherichia coli O157:H7 (O157) is the Shiga toxin-producing E. coli (STEC) serotype most frequently isolated and most often associated with hemolytic uremic syndrome (HUS) in the United States. Non-O157 STEC serotypes can also cause serious illness, but their impact as pathogens remains undefined. We compared characteristics of non-O157 and O157 STEC infections identified through sentinel surveillance.


METHODS
Sentinel sites included a metropolitan health maintenance organization laboratory and a hospital laboratory serving a small city and rural area. We received sorbitol-MacConkey agar plates from every stool culture performed at both sites during 2000-2006. Colony sweeps were screened for stx1 and stx2 by polymerase chain reaction. E. coli identity, serotype, and presence of stx1 and/or stx2 were confirmed on individual isolates.


RESULTS
Two hundred six STEC isolates were identified: 108 (52%) were non-O157 serotypes, and 98 (48%) were O157. Of non-O157 cases, 54% involved bloody diarrhea, and 8% involved hospitalization. Non-O157 isolates with at least stx2 were not more likely to cause severe illness (bloody diarrhea, hospitalization, or HUS) than were non-O157 isolates with only stx1. O157 cases were more likely than non-O157 cases to involve bloody diarrhea (78% vs 54%; P < .001), hospitalization (34% vs 8%; P < .001 and HUS (7% vs 0%; P = .005). When including only isolates with at least stx2, O157 cases were still more likely to involve bloody diarrhea (78% vs 56%; P = .02) and hospitalization (33% vs 12%; P = .01) than non-O157 cases.


CONCLUSIONS
Differences in severity among STEC infections could not be explained by stx2, suggesting that additional factors are important in STEC virulence.
Hedican
Erin B
EB
Acute Disease Investigation and Control Section and 2Public Health Laboratory, Minnesota Department of Health, St. Paul.
Medus
Carlota
C
Besser
John M
JM
Juni
Billie A
BA
Koziol
Bonnie
B
Taylor
Charlott
C
Smith
Kirk E
KE
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002648:Child; D002675:Child, Preschool; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology* / Q000473:pathology*; D019453:Escherichia coli O157 / Q000302:isolation & purification / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000235:genetics; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D012703:Serotyping; D022622:Shiga Toxin 1 / Q000235:genetics; D022641:Shiga Toxin 2 / Q000235:genetics; D054323:Shiga-Toxigenic Escherichia coli / Q000145:classification / Q000302:isolation & purification* / Q000472:pathogenicity*; D055815:Young Adult
D029968:Escherichia coli Proteins; D022622:Shiga Toxin 1; D022641:Shiga Toxin 2