Tóth István, Schmidt Herbert, Kardos Gábor, Lancz Zsuzsanna, Creuzburg Kristina, Damjanova Ivelina, Pászti Judit, Beutin Lothar, Nagy Béla
Veterinary Medical Research Institute of the Hungarian Academy of Sciences, 1143 Budapest, Hungary.
Appl Environ Microbiol. 2009 Oct;75(19):6282-91. doi: 10.1128/AEM.00873-09. Epub 2009 Aug 14.
Characterization of an Escherichia coli O157 strain collection (n = 42) derived from healthy Hungarian cattle revealed the existence of diverse pathotypes. Enteropathogenic E. coli (EPEC; eae positive) appeared to be the most frequent pathotype (n = 22 strains), 11 O157 strains were typical enterohemorrhagic E. coli (EHEC; stx and eae positive), and 9 O157 strains were atypical, with none of the key stx and eae virulence genes detected. EHEC and EPEC O157 strains all carried eae-gamma, tir-gamma, tccP, and paa. Other virulence genes located on the pO157 virulence plasmid and different O islands (O island 43 [OI-43] and OI-122), as well as espJ and espM, also characterized the EPEC and EHEC O157 strains with similar frequencies. However, none of these virulence genes were detected by PCR in atypical O157 strains. Interestingly, five of nine atypical O157 strains produced cytolethal distending toxin V (CDT-V) and carried genes encoding long polar fimbriae. Macro-restriction fragment enzyme analysis (pulsed-field gel electrophoresis) revealed that these E. coli O157 strains belong to four main clusters. Multilocus sequence typing analysis revealed that five housekeeping genes were identical in EHEC and EPEC O157 strains but were different in the atypical O157 strains. These results suggest that the Hungarian bovine E. coli O157 strains represent at least two main clones: EHEC/EPEC O157:H7/NM (nonmotile) and atypical CDT-V-producing O157 strains with H antigens different from H7. The CDT-V-producing O157 strains represent a novel genogroup. The pathogenic potential of these strains remains to be elucidated.
对源自匈牙利健康牛群的42株大肠杆菌O157菌株进行的特征分析表明存在多种致病型。肠致病性大肠杆菌（EPEC；eae阳性）似乎是最常见的致病型（22株），11株O157菌株是典型的肠出血性大肠杆菌（EHEC；stx和eae阳性），9株O157菌株是非典型的，未检测到关键的stx和eae毒力基因。EHEC和EPEC O157菌株均携带eae-γ、tir-γ、tccP和paa。位于pO157毒力质粒和不同O岛（O岛43 [OI-43]和OI-122）上的其他毒力基因，以及espJ和espM，在EPEC和EHEC O157菌株中的特征频率也相似。然而，在非典型O157菌株中通过PCR未检测到这些毒力基因中的任何一个。有趣的是，9株非典型O157菌株中有5株产生细胞致死扩张毒素V（CDT-V）并携带编码长极毛的基因。宏观限制性片段酶分析（脉冲场凝胶电泳）表明这些大肠杆菌O157菌株属于四个主要簇。多位点序列分型分析表明，五个管家基因在EHEC和EPEC O157菌株中相同，但在非典型O157菌株中不同。这些结果表明，匈牙利牛源大肠杆菌O157菌株至少代表两个主要克隆：EHEC/EPEC O157:H7/NM（无动力）和产生CDT-V的非典型O157菌株，其H抗原不同于H7。产生CDT-V的O157菌株代表一个新的基因组。这些菌株的致病潜力仍有待阐明。
