title: Virulence factors of avian Escherichia coli associated with swollen head syndrome.
abstract: Virulence characteristics of 50 strains of Escherichia coli isolated from chickens with swollen head syndrome were examined. The results were the following: in the absence of D-mannose, 74% of strains agglutinated guinea pig erythrocytes, but in the presence of D-mannose 32% agglutinated guinea-pig erythrocytes and 62% agglutinated human erythrocytes. When slide agglutination assays were carried out with antisera to adhesin of bovine and swine origin (K88, K99, F41, F42 987P and 2134P), only 14% of strains agglutinated with antiserum to F41. Colicin V was produced by 78% of the E. coli strains and 80% produced aerobactin. In the serum resistance test, 36 (72%) of strains showed resistance to normal chicken serum. Only seven (14%) strains expressed K1 capsular antigen, while motility was found in 62% of the strains.
authors.affiliation: Departmento de Microbiologia e Imunologia, Instituto de Biologia Universidade Estadual de Campinas, Campinas cep, SP, Brazil.
authors.forename: V R
authors.initials: VR
authors.lastname: Parreira
authors.forename: C W
authors.initials: CW
authors.lastname: Arns
authors.forename: T
authors.initials: T
authors.lastname: Yano