Hedican Erin B, Medus Carlota, Besser John M, Juni Billie A, Koziol Bonnie, Taylor Charlott, Smith Kirk E
Acute Disease Investigation and Control Section and 2Public Health Laboratory, Minnesota Department of Health, St. Paul.
Clin Infect Dis. 2009 Aug 1;49(3):358-64. doi: 10.1086/600302.
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.
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.
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.
Differences in severity among STEC infections could not be explained by stx2, suggesting that additional factors are important in STEC virulence.
大肠杆菌O157:H7（O157）是美国最常分离出的产志贺毒素大肠杆菌（STEC）血清型，且最常与溶血尿毒综合征（HUS）相关。非O157 STEC血清型也可导致严重疾病，但其作为病原体的影响尚不明确。我们比较了通过哨点监测确定的非O157和O157 STEC感染的特征。
哨点包括一个大都市健康维护组织实验室和一个为小城市及农村地区服务的医院实验室。我们收到了2000 - 2006年期间在这两个地点进行的每次粪便培养的山梨醇麦康凯琼脂平板。通过聚合酶链反应对菌落扫描进行stx1和stx2筛查。在单个分离株上确认大肠杆菌的身份、血清型以及stx1和/或stx2的存在情况。
共鉴定出206株STEC分离株：108株（52%）为非O157血清型，98株（48%）为O157。在非O157病例中，54%出现血性腹泻，8%需要住院治疗。与仅携带stx1的非O157分离株相比，至少携带stx2的非O157分离株导致严重疾病（血性腹泻、住院或HUS）的可能性并不更高。O157病例比非O157病例更易出现血性腹泻（78%对54%；P <.001）、住院（34%对8%；P <.001）和HUS（7%对0%；P =.005）。当仅纳入至少携带stx2的分离株时，O157病例仍比非O157病例更易出现血性腹泻（78%对56%；P =.02）和住院（33%对12%；P =.01）。
STEC感染严重程度的差异无法用stx2来解释，这表明其他因素在STEC毒力中起重要作用。
