COMPARISON BETWEEN ENTEROTOXIGENIC ESCHERICHIA-COLI STRAINS EXPRESSING F42, F41 AND K99 COLONIZATION FACTORS

Two enterotoxigenic Escherichia coli (ETEC) strains (coded 567/7 and 103) isolated from piglets with neonatal diarrhea were described as producers of a new adhesin (F42). With the use of molecular biology and immunology techniques such as DNA hybridization with probes for F41 and K99 genes and Western-blotting of the superficial proteins of these strains and standard E. coli strains carrying genes for F41 and K99 adhesins, it was demonstrated that this new adhesin either shares extensive genetic and immunological determinants with F41 adhesin or they are the same fimbriae.371186987

TRANSPOSON MUTAGENESIS AND MEMBRANE-PROTEIN STUDIES IN AN AVIAN COLISEPTICAEMIC ESCHERICHIA-COLI STRAIN

The pathogenicity, antibiotic resistance, plasmid DNA and membrane protein profiles of a colisepticaemic Escherichia coli strain (362) isolated from chickens was studied. It was verified that this strain harboured at least five plasmids. One 88.0 MD plasmid is non conjugative and is responsible for the production of colicin V and serum resistance. The 43.0 MD plasmid is responsible for resistance to bactericidal activity of serum and ampicilin. Curing of these plasmids did not decrease the pathogenicity of the strain. Transposon mutagenesis (Tnpho A) of strain 362 yielded a non-pathogenic derivative strain which had lost a 40.7 kD membrane protein, which is not correlated to the aerobactin and enterochelin systems. We suggest that this protein subunit is involved in the pathogenicity process of avian septicaemic E. coli strains.17191

PLASMID-MEDIATED PRODUCTION OF A NEW COLONIZATION FACTOR (F-42) IN ENTEROTOXIGENIC ESCHERICHIA-COLI

10463564

STUDIES OF THE GENETIC EXPRESSION OF 31A-FIMBRIAE BY 2 BOVINE SEPTICEMIC ESCHERICHIA-COLI STRAINS

Using transposon tnphoA, classical bacterial genetic assays, SDS-PAGE and Western blot of superficial proteins, we have studied the expression of the 31A fimbriae of two bovine wild-type septicaemic Escherichia coli strains. The genes responsible for encoding colonization factor 31A were located in both the plasmid (strain BZ2468) and the chromosome (strain BZ43). The results obtained using HeLa cell cultures led us to believe that the BZ43 strain could have another colonization factor besides 31A, since one mutant, which did not express fimbriae, was still able to adhere to HeLa cells.17436537

A DNA-PROBE TO IDENTIFY ENTEROTOXIGENIC ESCHERICHIA-COLI EXPRESSING PCF0159 COLONIZATION FACTOR

The expression of PCF0159 fimbriae by a ETEC Escherichia coli strain was blocked by using transposon TnphoA. The plasmidial DNA sequence which includes the insertion of the transposon was cloned and used as a DNA probe against E. coli strains expressing different colonization factors and enterotoxins. The DNA probe was specific only for those strains belonging either to the serotype 0159:H4 or carrier strains which expressed PCF0159 fimbriae operons.18335536

Pathogenicity characteristics of uropathogenic Escherichia coli strains

Seventeen wild-type uropathogenic Escherichia coli strains isolated from patients with urinary tract infection (UTI) and one pyelonephritis strain were studied for pathogenicity traits. Their plasmid, outer membrane protein, surface protein and RAPD DNA profiles, hemolysin and colicin production, type of fimbriae expressed and capacity of adhesion to uroepithelial cells were determined in an attempt to correlate these characteristics with pathogenicity. The only characteristic that had a consistent pattern in these types of E. coli was adhesion to uroepithelial cells.19191