Prevalence of Hemolysin Genes and Comparison of ehxA Subtype Patterns in Shiga Toxin-Producing Escherichia coli (STEC) and Non-STEC Strains from Clinical, Food, and Animal Sources
Prevalence of Hemolysin Genes and Comparison of ehxA Subtype Patterns in Shiga Toxin-Producing Escherichia coli (STEC) and Non-STEC Strains from Clinical, Food, and Animal Sources
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DOI：
10.1128/aem.02200-13
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发表时间：
2013-10-01
影响因子：
4.4
通讯作者：
Kase, Julie A.
中科院分区：
文献类型：
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作者：
Lorenz, Sandra C.;Son, Insook;Kase, Julie A.
产滋贺毒素大肠杆菌（STEC）属于某些血清群（e.例如，在一个实施例中，O157和O26）可导致严重的疾病，如溶血性尿毒症综合征（HUS），但其他菌株可能同样致病。虽然毒力因子，如stx和eae，已经得到了很好的研究，但对E。大肠杆菌溶血素基因（hlyA、ehxA、e-hlyA和sheA）与这些因子相关。溶血素是潜在的毒力因子，ehxA和hlyA与人类疾病有关，但sheA的意义尚不清楚。因此，435 E.大肠杆菌菌株属于62个不同的O血清型的特点，以调查基因的存在和溶血的表型表达。我们进一步研究了大肠杆菌中ehxA亚型的模式。临床、动物和食物来源的大肠杆菌分离株。she A和ehxA广泛分布，e-hlyA和hlyA少见，大多数菌株（86.7%）具有溶血性，且溶血性菌株（95%）明显高于非溶血性菌株（49%）（P <0.0001）。通过PCR结合限制性片段长度多态性分析进行ehxA亚型分型，得到6种密切相关的亚型（> 94.2%），其中亚型A/D为eae阴性的STECs，亚型B、C、E和F eae阳性。出乎意料的是，不同来源的分离株之间ehxA亚型模式存在显著差异（P <0.0001），这表明暴露和传播的简单线性模型需要修改;动物分离株主要携带A/C亚型（39.3%/42.9%），食物分离株主要携带A亚型（81.9%），临床分离株主要携带C亚型（66.4%）。某些O血清群与特定的ehxA亚型相关：A亚型与O104、O113和O8相关; B仅与O157相关; C亚型与O26、O111和O121相关。
Shiga toxin-producing Escherichia coli (STEC) belonging to certain serogroups (e. g., O157 and O26) can cause serious conditions like hemolytic-uremic syndrome (HUS), but other strains might be equally pathogenic. While virulence factors, like stx and eae, have been well studied, little is known about the prevalence of the E. coli hemolysin genes (hlyA, ehxA, e-hlyA, and sheA) in association with these factors. Hemolysins are potential virulence factors, and ehxA and hlyA have been associated with human illness, but the significance of sheA is unknown. Hence, 435 E. coli strains belonging to 62 different O serogroups were characterized to investigate gene presence and phenotypic expression of hemolysis. We further investigated ehxA subtype patterns in E. coli isolates from clinical, animal, and food sources. While sheA and ehxA were widely distributed, e-hlyA and hlyA were rarely found. Most strains (86.7%) were hemolytic, and significantly more hemolytic (95%) than nonhemolytic strains (49%) carried stx and/or eae (P < 0.0001). ehxA subtyping, as performed by using PCR in combination with restriction fragment length polymorphism analysis, resulted in six closely related subtypes (>94.2%), with subtypes A/D being eae-negative STECs and subtypes B, C, E, and F eae positive. Unexpectedly, ehxA subtype patterns differed significantly between isolates collected from different sources (P < 0.0001), suggesting that simple linear models of exposure and transmission need modification; animal isolates carried mostly subtypes A/C (39.3%/42.9%), food isolates carried mainly subtype A (81.9%), and clinical isolates carried mainly subtype C (66.4%). Certain O serogroups correlated with particular ehxA subtypes: subtype A with O104, O113, and O8; B exclusively with O157; C with O26, O111, and O121.