Andreoli Giuseppina, Merla Cristina, Valle Claudia Dalla, Corpus Francesco, Morganti Marina, D'incau Mario, Colmegna Silvia, Marone Piero, Fabbi Massimo, Barco Lisa, Carra Elena
1 Istituto Zooprofilattico Sperimentale della Lombardia e dell' Emilia Romagna "Bruno Ubertini," Pavia Unit, Strada Campeggi 59/61, 27100 Pavia, Italy.
2 Dipartimento di Scienze del Farmaco & Drug and Food Biotechnology Center (DFB), Università degli Studi del Piemonte Orientale "Amedeo Avogadro," Largo Donegani 2, 28100 Novara, Italy.
J Food Prot. 2017 Apr;80(4):632-639. doi: 10.4315/0362-028X.JFP-16-331.
Salmonella enterica serovar Typhimurium (STm) and its monophasic variant 4,[5],12:i:- (VMSTm) have been responsible for an increased number of foodborne infections in humans in Europe in recent years. The aim of this study was to investigate the origin of three foodborne salmonellosis outbreaks that occurred in Pavia Province (Lombardy region, northern Italy) in 2010. Phenotypic and genetic characteristics of the STm and VMSTm isolates from patients and from food that were recovered in the framework of the three outbreaks were evaluated through serotyping, phage typing, antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), and multiple-locus variable-number tandem repeat analysis (MLVA). Salami from three artisan producers, which had all purchased meat from the same slaughterhouse, was the food source of infection in outbreak I. STm isolates were recovered from salami and patients with symptoms of gastroenteritis. These isolates had the same PFGE type and the same rare MLVA profile (3-18-9-NA-211). The same molecular profiles were found in an STm isolate from a salami, which likely was the source of another family outbreak (II). A VMSTm strain with common phenotypic and molecular profiles was isolated from three hospitalized patients and identified as the cause of another putative outbreak (III). During the following 3 years (2011 through 2013), 360 salami produced in Pavia Province were monitored for the presence of S. enterica . In 2011, no STm and VMSTm isolates were recovered from 159 salami tested. During 2012 and 2013, 13.9% of 201 tested salami harbored S. enterica , and half of the isolates were VMSTm, mainly in salami from those artisan producers involved in the previous outbreaks. These isolates were genetically variable, especially in terms of MLVA profiles. The data collected suggest that from 2012, VMSTm has replaced STm in the environments of the salami producers monitored in this study, and these data confirm the dominance of this emergent serovar along the pork supply chain.
肠炎沙门氏菌鼠伤寒血清型（STm）及其单相变体4,[5],12:i:-（VMSTm）近年来在欧洲导致人类食源性感染病例数增加。本研究旨在调查2010年在意大利北部伦巴第大区帕维亚省发生的三起食源性沙门氏菌病暴发的源头。通过血清分型、噬菌体分型、抗菌药物敏感性试验、脉冲场凝胶电泳（PFGE）和多位点可变数目串联重复序列分析（MLVA），对在这三起暴发调查过程中从患者和食品中分离出的STm和VMSTm菌株的表型和遗传特征进行了评估。来自三家手工生产商的萨拉米香肠是疫情I的感染源，这三家生产商均从同一屠宰场采购肉类。从萨拉米香肠和患有肠胃炎症状的患者中分离出了STm菌株。这些菌株具有相同的PFGE型和相同的罕见MLVA谱型（3-18-9-NA-211）。在一份萨拉米香肠中分离出的一株STm菌株也具有相同的分子谱型，该菌株可能是另一起家庭疫情（疫情II）的源头。从三名住院患者中分离出了一株具有常见表型和分子谱型的VMSTm菌株，并确定其为另一起疑似疫情（疫情III）的病因。在随后三年（2011年至2013年）期间，对帕维亚省生产的360份萨拉米香肠进行了肠炎沙门氏菌监测。2011年，在检测的159份萨拉米香肠中未分离出STm和VMSTm菌株。在2012年和2013年期间，在检测的201份萨拉米香肠中，13.9%含有肠炎沙门氏菌，其中一半的分离株为VMSTm，主要存在于之前暴发疫情中涉事的手工生产商生产的萨拉米香肠中。这些分离株在基因上具有变异性，尤其是在MLVA谱型方面。收集到的数据表明，自2012年起，VMSTm在本研究监测的萨拉米香肠生产商环境中已取代了STm，这些数据证实了这种新出现的血清型在猪肉供应链中的主导地位。
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