Lack of expression of bundle-forming pili in some clinical isolates of enteropathogenic Escherichia coli (EPEC) is due to a conserved large deletion in the bfp operon

Enteropathogenic Escherichia coli (EPEC) produces a plasmid-encoded type IV pilus, called the bundle-forming pilus (BFP), involved in the formation of the localized adhesion onto epithelial cells. In this study, we demonstrat e that clinical isolates of serotypes O128ab:H2 and O119:H2 contain a ca. 1 3-kb deletion in the bfp operon, resulting in a lack of expression of these pill. An IS sequence with homology to the IS66 of Agrobucterium tumefacien s replaced the deleted bfp genes. These results suggest that the bfp operon was deleted through a transpositional event and that other adherence facto rs may mediate attachment of these bacteria to the host cells. (C) 1999 Fed eration of European Microbiological Societies. Published by Elsevier Scienc e B.V. All rights reserved.