Kučerová Dana, Koláčková Ivana, Karpíšková Renáta
Veterinary Research Institute, Brno, Czech Republic, e-mail:
Klin Mikrobiol Infekc Lek. 2018 Jun;24(2):36-40.
The aim of this study was to monitor characteristics of Shiga toxin-producing Escherichia coli (STEC) obtained from animals according to the serogroup they belonged to, Shiga toxin type and subtype and adhesion factor intimin. Then, based on the results, to evaluate the occurrence of Shiga toxin subtypes and their possible significance for humans.
The study included 131 STEC strains isolated from rectal swabs from cattle (80) and pigs (51) sampled on farms in the Czech Republic from 2000 to 2017. Selected strains differed in origin and serogroup. The presence of Shiga toxins, intimin and the Shiga toxin subtypes stx1a, stx1c, stx1d, stx2a, stx2b, stx2c, stx2d, stx2e, stx2g was determined by PCR.
The stx1 gene was confirmed in 33 % of the strains (43/131), the stx2 gene in 55 % (72/131) and 16 strains carried the genes for both toxins simultaneously (12 %). Strains harboring the eae gene were detected in 46 (35 %) cases, mostly in rectal swabs from cattle. STEC from cattle belonged to 21 different serogroups. The presence of Shiga toxin 1 (55; 69 %) predominated in these strains, with subtypes stx1a (54) and stx1d (1). Shiga toxin 2 was confirmed in 39 of the bovine strains (49 %), with the following subtypes: stx2a (9), stx2e (6), stx2g (3), stx2a, stx2c (5), stx2a, stx2b (1) and stx2c, stx2d (1). Also combinations of stx1a, stx2a (12) and stx1a, stx2c (2) were detected. STEC from pigs belonged to 5 different serogroups. Shiga toxin 2 was most frequently detected (49; 96 %), with subtypes stx2e (42) and stx2a (7). Shiga toxin 1 was detected in 4 strains (8 %), as subtypes stx1a (1) and stx1c (1) and also in the combination stx1a, stx2a (2).
STEC strains isolated from cattle, compared to those from pigs, belonged to a larger spectrum of serogroups, they more often carried adherence factor intimin and the diversity of Shiga toxin subtypes was higher, including those associated with serious human diseases. In the set of isolates from pigs, the stx2e gene predominated; its significance for human health has not been fully clarified yet.
本研究旨在根据产志贺毒素大肠杆菌（STEC）所属血清群、志贺毒素类型和亚型以及黏附因子紧密素，监测从动物身上分离得到的STEC的特征。然后，根据结果评估志贺毒素亚型的出现情况及其对人类的潜在意义。
本研究纳入了2000年至2017年期间从捷克共和国农场采集的牛（80份）和猪（51份）直肠拭子中分离出的131株STEC菌株。所选菌株在来源和血清群方面存在差异。通过聚合酶链反应（PCR）检测志贺毒素、紧密素以及志贺毒素亚型stx1a、stx1c、stx1d、stx2a、stx2b、stx2c、stx2d、stx2e、stx2g的存在情况。
33%（43/131）的菌株中检测到stx1基因，55%（72/131）的菌株中检测到stx2基因，16株菌株同时携带两种毒素的基因（12%）。在46例（35%）中检测到携带eae基因的菌株，大多来自牛的直肠拭子。来自牛的STEC属于21种不同血清群。这些菌株中志贺毒素1的存在占主导（55株；69%），亚型为stx1a（54株）和stx1d（1株）。在39株牛源菌株（49%）中确认了志贺毒素2，其亚型如下：stx2a（9株）、stx2e（6株）、stx2g（3株）、stx2a，stx2c（5株）；stx2a，stx2b（1株）以及stx2c，stx2d（1株）。还检测到stx1a，stx2a（12株）和stx1a，stx2c（2株）的组合。来自猪的STEC属于5种不同血清群。志贺毒素2最常被检测到（49株；96%），亚型为stx2e（42株）和stx2a（7株）。在4株（8%）中检测到志贺毒素1，亚型为stx1a（1株）和stx1c（1株），也检测到stx1a，stx2a（2株）的组合。
与从猪身上分离的STEC菌株相比，从牛身上分离的STEC菌株属于更广泛的血清群，它们更常携带黏附因子紧密素，并且志贺毒素亚型的多样性更高，包括那些与严重人类疾病相关的亚型。在猪源分离株中，stx2e基因占主导；其对人类健康的意义尚未完全阐明。
