Barco Lisa, Ramon Elena, Cortini Enzo, Longo Alessandra, Dalla Pozza Maria Cristina, Lettini Antonia Anna, Dionisi Anna Maria, Olsen John Elmerdahl, Ricci Antonia
1 World Organization for Animal Health (OIE), National Reference Laboratory for Salmonella, Istituto Zooprofilattico Sperimentale delle Venezie , Legnaro (Padova), Italy .
Foodborne Pathog Dis. 2014 Feb;11(2):138-44. doi: 10.1089/fpd.2013.1626. Epub 2013 Dec 14.
Salmonella enterica subsp. enterica serovar 4,[5],12:i:- DT193 is recognized as an emerging monophasic variant of Salmonella Typhimurium in many European countries. Resistance to ampicillin, streptomycin, sulphonamides, and tetracycline (R-type ASSuT) is described as one of the most common profiles of resistance within this clone. Recently, strains presenting such features were isolated from two unrelated outbreaks in Italy. Strains were characterized by pulsed-field gel electrophoresis (PFGE), performed with XbaI, BlnI, and SpeI, and multiple-locus variable-number tandem repeat analysis (MLVA). XbaI-PFGE showed strains related to the two outbreaks as indistinguishable. Conversely, both BlnI-PFGE and MLVA characterized the strains related the two outbreaks as different. XbaI-PFGE identified two profiles, differing by one band, within strains isolated from one of the two outbreaks. Also BlnI-PFGE and MLVA generated different profiles among the strains related to that outbreak. Combining the PFGE profiles obtained by XbaI and BlnI and comparing them with the MLVA profiles, the two methods grouped the same isolates based on identity. Moreover, genomic deletions of the genes included in the operon fljAB, the flanking iroB gene, and the closely located STM2757 gene were investigated. For all strains, the same profile of deletion characterized by the absence of fljA, fljB, and hin genes and the presence of STM2757 and iroB genes was identified. This profile of deletion represents a mixture between two profiles of Salmonella 4,[5],12:i:- described as the "Spanish" and the "U.S." clones. This study demonstrated that although strains of Salmonella 4,[5],12:i:- DT193 ASSuT are highly clonal, minor differences between strains may be seen during the same outbreak by using in parallel PFGE with different restriction enzymes, MLVA, and the analysis of molecular markers related to the operon fljAB. The combination of these different molecular approaches was essential to clarify the epidemiological relationship among the strains.
肠炎沙门氏菌亚种肠炎血清型4,[5],12:i:- DT193在许多欧洲国家被认为是鼠伤寒沙门氏菌的一种新兴单相变体。对氨苄西林、链霉素、磺胺类药物和四环素的耐药性（R型ASSuT）被描述为该克隆中最常见的耐药谱之一。最近，在意大利的两起无关疫情中分离出了具有此类特征的菌株。通过用XbaI、BlnI和SpeI进行脉冲场凝胶电泳（PFGE）以及多位点可变数目串联重复分析（MLVA）对菌株进行了特征分析。XbaI - PFGE显示与两起疫情相关的菌株无法区分。相反，BlnI - PFGE和MLVA均将与两起疫情相关的菌株鉴定为不同。XbaI - PFGE在从两起疫情之一分离出的菌株中鉴定出两种相差一条带的图谱。BlnI - PFGE和MLVA在与该疫情相关的菌株中也产生了不同的图谱。将XbaI和BlnI获得的PFGE图谱结合起来并与MLVA图谱进行比较，这两种方法基于同一性对相同的分离株进行了分组。此外，还研究了操纵子fljAB中包含的基因、侧翼iroB基因和紧密相邻的STM2757基因的基因组缺失情况。对于所有菌株，均鉴定出相同的缺失图谱，其特征为fljA、fljB和hin基因缺失，STM2757和iroB基因存在。这种缺失图谱代表了两种被描述为“西班牙”和“美国”克隆的肠炎沙门氏菌4,[5],12:i:-图谱的混合。本研究表明，尽管肠炎沙门氏菌4,[5],12:i:- DT193 ASSuT菌株具有高度克隆性，但在同一疫情期间，通过并行使用不同限制酶的PFGE、MLVA以及与操纵子fljAB相关的分子标记分析，可能会观察到菌株之间的细微差异。这些不同分子方法的结合对于阐明菌株之间的流行病学关系至关重要。
