Trabulsi, “Plasmids coding for drug resistance and localized adherence to HeLa cells

Plasmids coding for drug resistance and localized adherence (LA) to HeLa cells were found in two enteropathogenic Escherichia coli strains belonging to serotypes 055:H- and 055:H6. Strain 49-81 HSJ (055:H-) carries two plasmids, one coding for both ampicillin resistance (Apr) and LA (pMS49). Strain 71-82 HSJ (055:H6) harbors only one plasmid, coding for resistance to sulfadiazine, chloramphenicol, kanamycin, ampicillin, and LA (pMS71). Plasmids pMS49 and pMS71 were transferred to E. coli K-12 711 and from this strain to E. coli K-12 J53. Curing with acridine orange of an Apr LA ' transconjugant showed that both characteristics were lost simultaneously. The plasmids have a molecular weight of approximately 55 x 106 and are the first naturally recombinant plasmids coding for adherence and drug resistance described in enteropathogenic E. coli. The mechanisms of virulence of enteropathogenic Esche-richia coli (EPEC) have so far not been established. Toxin production (8, 9, 13) and adherence to human intestinal epithelium (4, 15, 21) and to cells in culture (4, 5, 10) have been studied. It was shown in our laboratory (16) that E. coli organisms adhere to HeLa cells in two different patterns