Tatarczak M, Wieczorek K, Possē B, Osek J
Department of Hygiene of Food of Animal Origin, National Veterinary Research Institute, Partyzantow 57, 24-100 Pulawy, Poland.
Vet Microbiol. 2005 Sep 30;110(1-2):77-85. doi: 10.1016/j.vetmic.2005.07.004.
Shiga toxin-producing Escherichia coli (STEC) is an important pathogen responsible for severe human intestinal and systemic infections. The bacterial factors required for colonization of the hosts are still not well defined. In this study, the prevalence of seven putative adhesive genes that are not encoded in the locus of enterocyte effacement (LEE) in 74 STEC strains isolated from humans (n=39), food (n=6), cattle (n=11), and pigs (n=18) was investigated by PCR. In addition, Shiga toxin (stx) and intimin (eaeA including alpha, beta, gamma, delta, epsilon, zeta variants) genes were tested. The most prevalent adhesin was that encoded by toxB gene (52 of 74 isolates; 70.3%). This marker was found in all 12 strains of O157:H7 serotype and in 23 of 32 (71.9%) isolates of the O157:NM serogroup. Moreover, this gene was also present in other 17 STEC of the non-O157 serogroup. The second most prevalent adhesin was that encoded by the lpfAO157/OI-154 gene (43 isolates; 58.1%). This marker was detected in LEE-positive strains of the O157 serogroup but also in 9 LEE-negative isolates of porcine origin. Several STEC isolates tested (42 strains; 56.7%) had the efa1 gene of the Efa1 putative adhesive marker. This adhesin was almost exclusively found among eaeA-positive strains recovered from humans, food and cattle. On the other hand, iha marker was detected either in LEE-positive (29 isolates) or LEE-negative (12 strains) STEC. Only two eaeA-negative strains had the saa putative adhesive gene. These results show that STEC strains may be able to express several putative adhesins. However, further studies are needed to evaluate the role of the genes identified in the present study in the pathogenesis of human infections.
产志贺毒素大肠杆菌（STEC）是导致人类严重肠道和全身感染的重要病原体。宿主定植所需的细菌因子仍未明确界定。在本研究中，通过聚合酶链反应（PCR）调查了从人类（n = 39）、食品（n = 6）、牛（n = 11）和猪（n = 18）中分离出的74株STEC菌株中，7个未在肠细胞脱落位点（LEE）编码的假定黏附基因的流行情况。此外，还检测了志贺毒素（stx）和紧密素（eaeA，包括α、β、γ、δ、ε、ζ变体）基因。最常见的黏附素是由toxB基因编码的黏附素（74株分离株中的52株；70.3%）。在所有12株O157:H7血清型菌株以及32株O157:NM血清群分离株中的23株（71.9%）中发现了该标记。此外，该基因也存在于其他17株非O157血清群的STEC中。第二常见的黏附素是由lpfAO157/OI - 154基因编码的黏附素（43株分离株；58.1%）。该标记在O157血清群的LEE阳性菌株中被检测到，但也在9株猪源LEE阴性分离株中被检测到。测试的几种STEC分离株（42株；56.7%）具有Efa1假定黏附标记的efa1基因。这种黏附素几乎仅在从人类、食品和牛中分离出的eaeA阳性菌株中发现。另一方面，iha标记在LEE阳性（29株分离株）或LEE阴性（12株菌株）的STEC中均有检测到。只有两株eaeA阴性菌株具有saa假定黏附基因。这些结果表明，STEC菌株可能能够表达多种假定黏附素。然而，需要进一步研究来评估本研究中鉴定的基因在人类感染发病机制中的作用。
