In previous studies, we have shown that atypical enteropathogenic Escherichia coli (aEPEC) strains are important diarrheal pathogens among Brazilian children. In the characterization of a collection of 126 aEPEC strains, we identified 29 strains expressing the localized-like adherence (LAL) pattern on HEp-2 cells and harboring large plasmids in the range of 60 to 98 MDa. In this study, we examined 18 of these strains for their ability to transfer the LAL phenotype to a E. coli K-12 C600 strain. In conjugation experiments, using eight strains which were resistant to one or more antimicrobials and positive for F-pili genes (traA), we were able to cotransfer antimicrobial resistance markers along with adhesion genes. By transforming E. coli DH5α with plasmid DNA from strains A46 (pIS46), A66 (pIS66) and A102 (pIS102), we were able to demonstrate that genes encoding ampicillin, tetracycline and LAL were encoded on a 98-MDa conjugative plasmid. To identify a gene responsible for LAL, we constructed a transposon mutant library of A102 strain. Among 18 mutants that did not adhere to HeLa cells, four carried insertions within fimbrial genes (fimA and traJ) and agglutinin genes (tia and hek). Using these Tn5 mutants as donors, we were able to obtain kanamycin-resistant E. coli MA3456 transconjugants. Sequence analysis of the plasmid genes revealed a region exhibit to 80 and 73% amino acid similarities to the agglutinins Tia and Hek, respectively. In this study, we have identified three large conjugative plasmids, pIS46, pIS66 and pIS102, coding for antimicrobial resistance and localized-like adherence (LAL) to HeLa cells. In addition, we identified a tia/hek homolog encoded on the pIS102 plasmid, which seems to be involved in adhesion of A102 strain.

中文翻译：

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在非典型肠致病性大肠杆菌菌株中编码抗生素抗性和局部样粘附的大质粒。

在以前的研究中，我们已经表明，非典型肠致病性大肠杆菌（aEPEC）菌株是巴西儿童中重要的腹泻病原体。在表征126株aEPEC菌株的过程中，我们鉴定了29株在HEp-2细胞上表达局部样粘附（LAL）模式并具有60至98 MDa范围内的大质粒的菌株。在这项研究中，我们检查了这些菌株中的18种将LAL表型转移至大肠杆菌K-12 C600菌株的能力。在结合实验中，使用八种对一种或多种抗菌素具有抗性并且对F-菌毛基因（traA）呈阳性的菌株，我们能够将抗微生物抗性标记物与粘附基因一起共转移。通过用菌株A46（pIS46），A66（pIS66）和A102（pIS102）的质粒DNA转化大肠杆菌DH5α，我们能够证明编码氨苄青霉素，四环素和LAL的基因是在98-MDa偶联质粒上编码的。为了鉴定负责LAL的基因，我们构建了A102菌株的转座子突变文库。在不粘附于HeLa细胞的18个突变体中，有四个在纤维基因（fimA和traJ）和凝集素基因（tia和hek）内进行了插入。使用这些Tn5突变体作为供体，我们能够获得抗卡那霉素的大肠杆菌MA3456转导结合体。质粒基因的序列分析表明，该区域与凝集素Tia和Hek分别具有80％和73％的氨基酸相似性。在这项研究中，我们确定了三个大的共轭质粒，pIS46，pIS66和pIS102，它们编码对HeLa细胞的抗药性和局部样粘附（LAL）。此外，