Two enteropathogenic strains of Escherichia coli (EEC) differed from a nonenteropathogenic strain of E. coli (NEEC) in their association with porcine small intestinal epithelium. The EEC characteristically were found along villi from tip to base and contiguous to the brush border. They were not in crypts. In contrast, the NEEC characteristically remained in the central lumen near the tips of villi and was only occasionally contiguous to the brush border. No organisms were detected within

more »

... ial cells. The difference in distribution between EEC and NEEC was apparent in ligated jejunal loops 45 min postexposure. The association between host and bacterial cells was most consistently demonstrated on frozen sections of intestine, as other histological techniques removed many bacteria. However, cellular details of the association were best demonstrated in chemically fixed tissues. with that of a porcine NEEC strain, and (iii) to compare different methods of demonstrating and quantitating this association in the pig intestine. MATERIALS AND METHODS Bacteria. Thc EEC strains used were 263 [serotype 08:K87(B)88a, b(L):H19] and 431 [serotype 0101: KU460(A) :NM] originally isolated from piglets with diarrhea. The NEEC strain 123 (serotype 043:K-: H28) originated from a healthy piglet. All three strains were used in the nonpiliated phase as determined by electron microscopic examination. Cultures were maintained on Trypticase soy agar (BBL; agar) in sealed tubes, subcultured on agar with 5%c sheep blood (blood-agar), and grown overnight in Trypticase soy broth (BBL; broth) at 37 C. Dilutions were made in broth immediately before the pigs were exposed. Pigs. In experiment I (intragastric exposure), 28 pigs from eight naturally farrowed litters were separated from the sow immediately after birth prior to nursing, kept in individual cardboard boxes under heat lamps, not fed, and exposed to E. coli 12 hr after birth. Pigs in the first four litters (experiment 595 on May 8, 2020 by guest http://iai.asm.org/ Downloaded from