Sváb Domonkos, Tóth István
Hungarian Academy of Sciences Veterinary Medical Research Institute, Budapest, Hungary.
Acta Vet Hung. 2012 Mar;60(1):1-15. doi: 10.1556/AVet.2012.001.
Long polar fimbriae (Lpf) are recently discovered adhesins and increasingly important genetic markers of pathogenic Escherichia coli strains. The presence and genotype diversity of Lpf operons was screened in a collection of 97 Escherichia coli O157 strains representing different pathotypes, isolated from healthy cattle (n = 43) and human patients (n = 54) in several countries. Individual structural genes of Lpf were scanned by PCR, and allelic variants were detected with a recently developed typing scheme. Ninety-five strains carried at least one whole Lpf operon (genes lpfABCD and/or lpfABCDE). The 64 enterohaemorrhagic (EHEC) and 24 enteropathogenic (EPEC) strains all carried two Lpf operons, allele 3 of lpfA1 and allele 2 of lpfA2, a combination characteristic of the O157:H7/NM serotype. Out of the 9 bovine atypical (AT; stx-, eae-) strains, 7 carried one complete Lpf operon, allele 1 of lpfA2. The atypical strains belonged to main phylogenetic groups A and B1, while the EHEC and EPEC strains were from group D. Lpf variants carried by the 72 strains of the Escherichia coli Reference Collection (ECOR) were determined with the same typing scheme. Alleles were detected in 25 strains, of which 6 were found negative for the respective Lpf operons in earlier studies. The marker value of the Lpf allelic combination for the O157:H7/NM serotype was confirmed, and further evidence was given for the presence of at least two different genetic lineages of atypical bovine E. coli O157 strains.
长极毛（Lpf）是最近发现的黏附素，也是致病性大肠杆菌菌株日益重要的遗传标记。在从几个国家的健康牛（n = 43）和人类患者（n = 54）中分离出的97株代表不同致病型的大肠杆菌O157菌株中，筛选了Lpf操纵子的存在和基因型多样性。通过PCR扫描Lpf的各个结构基因，并用最近开发的分型方案检测等位基因变体。95株菌株携带至少一个完整的Lpf操纵子（基因lpfABCD和/或lpfABCDE）。64株肠出血性大肠杆菌（EHEC）和24株肠致病性大肠杆菌（EPEC）菌株均携带两个Lpf操纵子，即lpfA1的等位基因3和lpfA2的等位基因2，这是O157:H7/NM血清型的特征组合。在9株牛非典型（AT；stx-，eae-）菌株中，7株携带一个完整的Lpf操纵子，即lpfA2的等位基因1。非典型菌株属于主要系统发育群A和B1，而EHEC和EPEC菌株来自群D。用相同的分型方案确定了大肠杆菌参考菌株集（ECOR）的72株菌株携带的Lpf变体。在25株菌株中检测到等位基因，其中6株在早期研究中被发现各自的Lpf操纵子呈阴性。Lpf等位基因组合对O157:H7/NM血清型的标记价值得到证实，并进一步证明了非典型牛大肠杆菌O157菌株至少存在两种不同的遗传谱系。
