Characterization of 20K fimbria, a new adhesin of septicemic and diarrhea-associated Escherichia coli strains, that belongs to a family of adhesins with N-acetyl-D-glucosamine recognition

Abstract

Bovine septicemic Escherichia coli 31A agglutinates bovine, rabbit, and human erythrocytes and adheres in vitro to the brush border of bovine or ovine intestinal epithelial cells and to the human colon carcinoma Caco-2 cell line. The adhesion and hemagglutination of E. coli 31A are mediated by a chromosome-encoded fimbrial adhesin serologically distinct from known fimbrial adhesins found in enterotoxigenic and septicemic bovine E. coli strains. By electron microscopy studies the fimbriae designated 20K were observed as fine flexible filaments (diameter, 3 nm) and the purified major fimbrial subunit appeared with an apparent molecular mass of 20,000 Da. Western blot (immunoblot) analysis, N-terminal sequence alignment, and amino acid composition revealed a high homology with the N-acetyl-D-glucosamine-specific G fimbria of human uropathogenic E. coli and with fimbriae belonging to the F17 family produced by bovine enterotoxigenic and invasive E. coli strains. Immunological study revealed that 20K fimbria was closely related to G fimbria and represents a serological variant of F17 fimbria. Hemagglutination and adhesion inhibition assays demonstrated that 20K, G, and F17 fimbriae bind to an N-acetyl-D-glucosamine-containing receptor, but each probably binds to different oligosaccharide sequences or different receptors on host tissues. 20K fimbriae were produced by a limited group of clonally related strains with the unusual m-inositol-positive phenotype and appeared highly associated with the plasmid-encoded CS31A surface antigen. It was expected that 20K-and CS31A-positive E. coli strains with the m-inositol-positive phenotype could represent a new example of association between bacterial clones and a plasmid-mediated virulence factor. An examination of natural occurrence of 20K fimbriae among a large collection of human and animal pathogenic E. coli showed that 20K fimbria is the prominent adhesin among bovine septicemic E. coli isolated from European countries.

Association of genes encoding P fimbriae, CS31A antigen and EAST 1 toxin among CNF1-producing Escherichia coli strains from cattle with septicemia and diarrhea

“…Therefore, strains producing both the CNF1 toxin and the CS31A antigen represent a new example of association between bacterial clones and plasmidmediated virulence factors. The gene encoding the F17 structural subunit was not detected among CNF1-producing strains whereas F17 are usually detected on about 50% of CS31A-producing pathogenic E. coli isolated from calves [11]. In accordance with results previously described [16], we suggest that genes encoding CNF1 and F17 are not present together on the bacterial chromosome.…”

“…In a previous report, we have demonstrated that bovine CNF2-producing E. coli were genetically associated with ¢mbriae belonging to the F17 family [10]. In contrast, these CNF2-positive E. coli did not express the a¢mbrial CS31A adhesin whereas F17 ¢mbriae were often associated with CS31A in bovine isolates [10,11]. The CS31A adhesin, ¢rst described on E. coli strains isolated from calves with septicemia or diarrhea, is closely related to K88 ¢brillae expressed by porcine ETEC and promotes adhesion to an N-acetylneuraminic acid-containing receptor present in human Int-407 cells [12^14].…”

“…More recently, CS31A-related antigens have been described on E. coli strains isolated from stools of hospitalized patients with diarrhea and on Klebsiella pneumoniae strains involved in nosocomial infections [14,15]. Fimbriae belonging to the F17 family were produced by E. coli strains isolated from septicemic or diarrheic calves and lambs and promote inhibitable Nacetyl-D-glucosamine in vitro adhesion on calf intestinal villi [10,11].…”

Fimbriae and adherence ofStenotrophomonas maltophiliato epithelial cells and to abiotic surfaces

“…We found that S. maltophilia and purified SMF-1 agglutinated mouse and hen erythrocytes in the presence of 1% D-mannose but did not agglutinate sheep, ox, horse, or human RBC, suggesting species-specific recognition. N-terminal amino acid sequence analysis of the major repeating subunit of SMF-1 displayed 60% similarity with the fimbrial adhesins family comprising K99, F17, 20K, and G fimbriae of E. coli pathogroups, and CupA of P. aeruginosa (Guinée et al, 1976;Rhen et al, 1986;Lintermans et al, 1988;Bertin et al, 1996;Klemm and Schembri 2000;Vallet et al, 2001). This suggests that this fimbrial family extends to other genetically distant nonenteric bacterial genera.…”

“…Purified SMF-1 agglutinated erythrocytes of several animal species and this activity was inhibited by anti-SMF-1 antibodies. The major fimbrial subunit produced by S. maltophilia , a polypeptide of 17 kDa, was found to be highly related to the family of fimbrial adhesins comprised by the G, F17, K99 and 20K fimbriae produced by several Escherichia coli pathogroups, and CupA of Pseudomonas aeruginosa (Guinée et al ., 1976;Rhen et al ., 1986;Lintermans et al ., 1988;Bertin et al ., 1996;Klemm and Schembri, 2000;Vallet et al ., 2001). This relatedness, the ability to agglutinate erythrocytes, and the presence of abundant fimbriae on adhering organisms suggest that the SMF-1 fimbriae may be important for the adhesiveness on abiotic and biotic surfaces, and probably to the pathobiology caused by this emerging pathogen.…”