Kapperud G, Rørvik L M, Hasseltvedt V, Høiby E A, Iversen B G, Staveland K, Johnsen G, Leitao J, Herikstad H, Andersson Y
National Institute of Public Health, Oslo, Norway.
J Clin Microbiol. 1995 Mar;33(3):609-14. doi: 10.1128/jcm.33.3.609-614.1995.
In the period from May through June 1994, an increase in the number of domestic cases of Shigella sonnei infection was detected in several European countries, including Norway, Sweden, and the United Kingdom. In all three countries epidemiological evidence incriminated imported iceberg lettuce of Spanish origin as the vehicle of transmission. The outbreaks shared a number of common features: a predominance of adults among the case patients, the presence of double infections with other enteropathogens, and the finding of two dominant phage types among the bacterial isolates. In Norway 110 culture-confirmed cases of infection were recorded; more than two-thirds (73%) were adults aged 30 to 60 years. A nationwide case-control study comprising 47 case patients and 155 matched control individuals showed that the consumption of imported iceberg lettuce was independently associated with an increased risk of shigellosis. Epidemiological investigation of a local outbreak incriminated iceberg lettuce from Spain, consumed from a salad bar, as the source. The presence of shigellae in the suspected food source could not be documented retrospectively. However, high numbers of fecal coliforms were detected in iceberg lettuce from patients' homes. Three lettuce specimens yielded salmonellae. The imported iceberg lettuce harbored Escherichia coli strains showing resistance to several antimicrobial agents, including ampicillin, ciprofloxacin, gentamicin, and trimethoprim-sulfamethoxazole. During the outbreak it is likely that thousands of Norwegians and an unknown number of consumers in other countries were exposed to coliforms containing antibiotic resistance genes.
1994年5月至6月期间，在包括挪威、瑞典和英国在内的几个欧洲国家，检测到国内宋内志贺菌感染病例数有所增加。在这三个国家，流行病学证据均表明，源自西班牙的进口卷心莴苣是传播媒介。这些疫情有一些共同特征：病例患者中成年人占多数，存在与其他肠道病原体的双重感染，并且在细菌分离株中发现了两种主要噬菌体类型。在挪威，记录了110例经培养确诊的感染病例；超过三分之二（73%）为30至60岁的成年人。一项全国性病例对照研究纳入了47例病例患者和155名匹配的对照个体，结果显示，食用进口卷心莴苣与志贺菌病风险增加独立相关。对一次局部疫情的流行病学调查认定，一家沙拉吧供应的来自西班牙的卷心莴苣是源头。无法追溯性地证实可疑食物源中存在志贺菌。然而，在患者家中的卷心莴苣中检测到大量粪大肠菌群。三份莴苣样本检出沙门氏菌。进口卷心莴苣中携带的大肠杆菌菌株对包括氨苄青霉素、环丙沙星、庆大霉素和甲氧苄啶-磺胺甲恶唑在内的多种抗菌药物具有耐药性。在疫情期间，可能有数千名挪威人以及其他国家数量不明的消费者接触到了含有抗生素耐药基因的大肠菌群。
