Division of Bacteriology, Osaka Prefectural Institute of Public Health, Nakamichi 1-3-69, Higashinari-ku, Osaka, Japan.
Foodborne Pathog Dis. 2011 Oct;8(10):1083-8. doi: 10.1089/fpd.2011.0862. Epub 2011 May 25.
In Osaka Prefecture, Japan, three foodborne outbreaks were caused by Salmonella enterica serotype Montevideo in rapid succession between September 2007 and May 2008. Further, Salmonella Montevideo was also isolated from several sporadic diarrhea patients and asymptomatic carriers examined during approximately the identical period. To investigate the relatedness of the isolates, we performed antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE) analysis, and multiple-locus variable-number tandem repeat (VNTR) analysis (MLVA) for 29 Salmonella Montevideo isolates obtained in this region between 1991 and 2008. Although antimicrobial susceptibility tests had low discriminatory power, PFGE patterns revealed 17 unique types with <90% similarity in combined analyses involving XbaI and BlnI. Moreover, we detected three VNTR loci that were useful to genotype Salmonella Montevideo isolates, with our method ultimately classifying the isolates into 11 MLVA types based on differences in repeat unit number in each examined locus. Six isolates obtained from patients of two separate foodborne disease outbreaks, one sporadic patient, and three different carriers between 2007 and 2008 had nearly identical PFGE patterns and were classified into the identical MLVA type; further, the isolates with this PFGE and MLVA pattern appeared only at that time between 1991 and 2008. These data strongly suggest that genetically identical Salmonella Montevideo strains may have caused the 2007 and 2008 outbreaks in Osaka Prefecture. Our results demonstrate that PFGE using XbaI and BlnI is useful for discriminating between Salmonella Montevideo isolates, even within a limited area, and reconfirm that continuous epidemiological surveillance for bacterial intestinal infections such as salmonellosis may be useful to not only monitor changes in the genetic diversity of isolates, but to also detect diffuse outbreaks.
在日本大阪府，2007 年 9 月至 2008 年 5 月期间，相继发生了三起因肠炎沙门氏菌血清型蒙特维多引起的食源性疾病暴发。此外，在大约相同的时期，还从一些散发性腹泻患者和无症状携带者中分离出了沙门氏菌蒙特维多。为了调查这些分离株的相关性，我们对该地区 1991 年至 2008 年间获得的 29 株肠炎沙门氏菌蒙特维多进行了抗菌药物敏感性试验、脉冲场凝胶电泳（PFGE）分析和多位点可变数目串联重复（VNTR）分析（MLVA）。尽管抗菌药物敏感性试验的区分力较低，但 PFGE 图谱显示，在 XbaI 和 BlnI 联合分析中，有 17 种独特的类型相似度<90%。此外，我们检测到三个 VNTR 基因座，这些基因座可用于对肠炎沙门氏菌蒙特维多分离株进行基因分型，我们的方法最终根据每个检测基因座重复单元数的差异，将分离株分为 11 种 MLVA 类型。2007 年至 2008 年间从两起食源性疾病暴发的患者、一名散发性患者和三名不同携带者中获得的 6 株分离株具有几乎相同的 PFGE 图谱，并被归类为相同的 MLVA 型；此外，具有这种 PFGE 和 MLVA 模式的分离株仅在 1991 年至 2008 年之间出现。这些数据强烈表明，遗传上相同的肠炎沙门氏菌蒙特维多菌株可能是导致大阪府 2007 年和 2008 年暴发的原因。我们的结果表明，即使在有限的区域内，使用 XbaI 和 BlnI 的 PFGE 对于肠炎沙门氏菌分离株的区分也很有用，并再次证实，对细菌性肠道感染（如沙门氏菌病）的连续流行病学监测不仅有助于监测分离株遗传多样性的变化，还可用于检测散发性暴发。
