Virulence factors of Escherichia coli isolated from bovine clinical mastitis.
Escherichia coli isolates from bovine mastitis were examined for a selection of virulence factors. The strains originated from Finland and Israel, which have differences in the proportion of mastitis caused by E. coli, clinical pictures of coliform mastitis, environmental conditions and herd management. The genes of nine virulence factors were detected by polymerase chain reaction. Presence of K1 and K5 capsules was assessed by use of specific bacteriophages. Serum resistance was tested by a turbidimetric assay. Out of 160 Finnish isolates, 37% had traT, 14% cnf2, 8% cnf1, 11% aer, 9% f17, 8% sfa, 7% pap, 1% afa8D and 1% afa8E. Out of 113 Israeli isolates, 41% had traT, 4% aer, 3% cnf2, 1% cnf1, 1% sfa and 1% f17. Some of the genes were distributed among two major pathotype groups, with either f17 family or sfa, pap and cnf1 as major determinants. Genes for F17a, CS31A, Afa7D and Afa7E were not detected. Altogether 49% of Finnish and 42% of Israeli isolates had at least one virulence gene, but genes other than traT were present in only 24% of Finnish and 5% of Israeli isolates. Serum resistance was more common among Finnish (94/160) than Israeli isolates (19/113). K1 and K5 capsules were not detected.
Kaipainen
T
T
Faculty of Veterinary Medicine, Saari Unit, University of Helsinki, Pohjoinen pikatie 800, 04920 Saarentaus, Finland. tanja.kaipainen@helsinki.fi
Pohjanvirta
T
T
Shpigel
N Y
NY
Shwimmer
A
A
Pyörälä
S
S
Pelkonen
S
S
D000818:Animals; D016667:Bacterial Capsules / Q000235:genetics*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001483:Base Sequence; D001770:Blood Bactericidal Activity; D002417:Cattle; D017931:DNA Primers; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity*; D029968:Escherichia coli Proteins / Q000235:genetics; D005387:Finland; D005798:Genes, Bacterial; D007557:Israel; D008414:Mastitis, Bovine / Q000382:microbiology*; D009391:Nephelometry and Turbidimetry / Q000662:veterinary; D000073718:Pancreatitis-Associated Proteins; D016133:Polymerase Chain Reaction / Q000662:veterinary; D014774:Virulence / Q000235:genetics
D001425:Bacterial Outer Membrane Proteins; D017931:DNA Primers; D029968:Escherichia coli Proteins; D000073718:Pancreatitis-Associated Proteins; C000612141:REG3A protein, human; C036297:TraT protein, E coli