Submitted to: American College of Veterinary Pathologists Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 12/11/2002
Publication Date: 9/20/2002
Citation: JORDAN, D., TORRES, A., BOOHER, S., NYSTROM, E.A., KAPER, J., MOON, H. DO LONG POLAR FIMBRIAE FACILITATE COLONIZATION BY ESCHERICHIA COLI O157:H7 IN PIGS? VETERINARY PATHOLOGY. 2002. V. 39. ABSTRACT P. 638. Interpretive Summary:
Technical Abstract: The contribution of long polar fimbriae (lpf) has been evaluated for the development of attachment and effacement lesions in the intestines of germ-free piglets. Loci have been identified in E.coli O157:H7 that bear homology to lpf genes in Salmonella enterica, serovar typhimurium that are important for colonization and virulence for Salmonella. In our experiments, two isogenic mutants of Escherichia coli O157:H7 strain 86-24 were evaluated, a single mutant, lpfA1-, and a double mutant, lpfA1-lpfA2-. Germ-free pigs were inoculated at 24 hours old with 10**5 cfu of bacteria. Eight pigs were infected with the single lpfA1 mutant strain, four with the double mutant, nine with the wild type, and three were inoculated with a nonpathogenic strain of E. coli. Pigs were necropsied at 24 hours post-inoculation. To evaluate colonization, tissues were collected for histopathology. Multiple sections of intestine were scored for the extensiveness of attachment and effacement lesions. The results showed a minimal reduction in colonization in the intestine by the single lpfA1 mutant when compared to the wild type strain, with the average colonization scores in the same category (moderate, 10%-50% affected). However, the tissues from the double mutant had a greater reduction in colonization with the A/E scores in the minimal category (0%-10% affected). From these data, it suggests that lpf does facilitate colonization, however, some colonization and lesion development still occurs. These results support the in vitro work that adherence to tissue culture cells is reduced.