Shigella flexneri is prevalent worldwide and is the most common Shigella species in many countries. At least 19 S. flexneri serotypes exist, and serotype information is important for epidemiologic and vaccine development purposes. We evaluated the performance of real-time PCR assays for O-antigen modification genes to identify the major serotypes on isolates and direct stool samples. The assays were formulated into two multiplex panels: one panel included gtrII, gtrV, gtrX, oac, and wzx6 to identify S. flexneri serotypes 2a, 2b, 3a, 5a, 5b, 6, and X, and the other panel included ipaH, gtrI, gtrIc, and gtrIV to confirm Shigella detection and further identify S. flexneri serotypes 1a, 1b, 1d, 3b, 4a, 4b, 7a, and 7b. We first evaluated 283 Shigella isolates, and PCR serotyping demonstrated 97.0% (95% confidence interval, 93.0% to 99.0%) sensitivity and 99.9% (99.9% to 100%) specificity compared to conventional serotyping. The assays then were utilized on direct stool specimens. A quantitative detection algorithm was developed with a validation set of 174 Shigella culture-positive stool samples and further tested with a derivation set of 164 samples. The PCR serotyping on stool achieved 93% (89% to 96%) sensitivity and 99% (99% to 100%) specificity compared to serotyping. Most discrepancies were genotypic-phenotypic discordance, not genotypic failure. These real-time PCR assays provide an efficient and novel tool for S. flexneri serotype identification.

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直接在粪便样品上进行弗氏志贺氏菌分子分型分析的评估

弗氏志贺氏菌在世界范围内普遍存在，并且是许多国家中最常见的志贺氏菌物种。存在至少19种弗氏链球菌血清型，并且血清型信息对于流行病学和疫苗开发目的是重要的。我们评估了O抗原修饰基因的实时PCR分析的性能，以鉴定分离株和直接粪便样品上的主要血清型。所述测定配制成两个复用面板：一个面板包括gtrII，gtrV，gtrX，OAC，并且wzx6识别弗氏志贺菌血清型2A，2B，3A，5A，图5B，图6和X，和另一个面板包括ipaH基因， GTRI，gtrIc和gtrIV确认志贺氏菌的检测和进一步识别弗氏志贺菌血清型1A，1B，1D，3B，4A，4B，7A和7B。我们首先评估了283株志贺氏菌分离物，与传统的血清分型相比，PCR血清分型显示出97.0％（95％置信区间，93.0％至99.0％）的敏感性和99.9％（99.9％至100％）的特异性。然后将测定用于直接粪便标本。开发了定量检测算法，并使用174种志贺氏菌进行了验证培养阳性的粪便样本，并用164个样本的派生集进行进一步测试。与血清分型相比，粪便上的PCR血清分型获得了93％（89％至96％）的敏感性和99％（99％至100％）的特异性。大多数差异是基因型-表型不一致，而不是基因型失败。这些实时PCR测定法为弗氏链球菌血清型鉴定提供了有效且新颖的工具。