RESUMO
A quantitative microtiter method using chicken plasma is described for determining the degree of complement resistance or sensitivity of avian Escherichia coli isolates. Results obtained with the microtiter method using chicken plasma were compred with results obtained using commercially available standardized guinea pig serum as the source of complement. The test organisms consisted of five isolates of E. coli isolated from chickens. Three isolates were from flocks with colisepticemia; one was from a flock with omphalitis; and one isolate was a non-pathogenic control. Data were accumulated from the five avian E. coli isolates incubated at 35 C with either chicken plasma or guinea pig serum and with heat-inactivated chicken plasma or guinea pig serum. The microtiter results of the chicken plasma and guinea pig serum had a statistically positive correlation. The use of commercially available guinea pig serum in the test system will allow for standardization of this method.
Assuntos
Atividade Bactericida do Sangue , Galinhas/imunologia , Proteínas do Sistema Complemento/imunologia , Escherichia coli/imunologia , Cobaias/imunologia , Animais , Galinhas/sangue , Infecções por Escherichia coli/microbiologia , Infecções por Escherichia coli/veterinária , Cobaias/sangue , Soros Imunes/imunologia , Doenças das Aves Domésticas/microbiologiaRESUMO
Twenty avian Escherichia coli isolates from normal and diseased chickens were compared by use of three virulence tests. These tests included the uptake of Congo red dye, an embryo lethality test, and a quantitative microtiter complement resistance test. A direct correlation was seen between the results of the complement resistance test and the embryo lethality test. The results of the Congo red test did not correlate with the two other tests.
Assuntos
Técnicas Bacteriológicas/veterinária , Galinhas/microbiologia , Vermelho Congo , Escherichia coli/patogenicidade , Animais , Valor Preditivo dos Testes , VirulênciaRESUMO
Cecal samples from 100 broiler flocks were cultured for Escherichia coli and Salmonella. Samples were selected from flocks classified as either "good" or "poor" producers by a production formula. In an attempt to identify predictors of flock productivity, isolates were studied for differences in antibiotic resistances, hemagglutination of erythrocytes, production of colicins, production of siderophores, type of hemolysis, resistance to host complement, and presence of plasmids. S. typhimurium (copenhagen) was isolated from one poor producing flock and three good producers. Salmonella isolates showed no significant differences in the parameters studied. The E. coli isolates showed significant differences only for the presence of plasmids. These data indicate that differences in host intestinal E. coli from good and poor producing flocks do not predict flock productivity.
Assuntos
Galinhas/microbiologia , Escherichia coli/isolamento & purificação , Salmonella/isolamento & purificação , Animais , Ceco/microbiologia , Galinhas/fisiologia , Colicinas/biossíntese , Proteínas do Sistema Complemento/imunologia , Resistência Microbiana a Medicamentos , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/fisiologia , Hemaglutinação , Hemólise , Quelantes de Ferro/metabolismo , Plasmídeos , Salmonella/efeitos dos fármacos , Salmonella/genética , Salmonella/fisiologia , SideróforosRESUMO
Results with four pathogenic avian Escherichia coli isolates and one avirulent isolate in a complement resistance test, a chicken lethality test, and a chicken embryo lethality test were compared. Results of the complement resistance test with these isolates were highly correlated to results of the chicken lethality test of virulence. The chicken embryo test yielded results that were of a medium positive correlation with the chicken lethality results. The results of the complement resistance and chicken embryo lethality tests were highly correlated.
Assuntos
Galinhas , Proteínas do Sistema Complemento/imunologia , Infecções por Escherichia coli/veterinária , Escherichia coli/patogenicidade , Doenças das Aves Domésticas/microbiologia , Animais , Bioensaio , Embrião de Galinha , Escherichia coli/classificação , Infecções por Escherichia coli/microbiologia , Sorotipagem , VirulênciaRESUMO
Three of four virulent avian Escherichia coli isolates transferred a single large molecular-weight R-plasmid to two recipient E. coli strains. Antibiotic resistances transferred included streptomycin (two isolates) and streptomycin-tetracycline-sulfa (one isolate). Production of colicin and siderophores, complement resistance, and embryo lethality present in the virulent isolates were not transferred to recipient organisms. From the results, it appears that the R-plasmids of these virulent avian E. coli are not associated with virulence.
Assuntos
Conjugação Genética , Infecções por Escherichia coli/veterinária , Escherichia coli/genética , Doenças das Aves Domésticas/microbiologia , Fatores R , Animais , Galinhas , Proteínas do Sistema Complemento/imunologia , Resistência Microbiana a Medicamentos/genética , Escherichia coli/efeitos dos fármacos , Escherichia coli/imunologia , Infecções por Escherichia coli/microbiologia , Fenótipo , Virulência/genéticaRESUMO
Complement resistance, antibiotic resistance profiles, and virulence profiles of 80 Escherichia coli isolates from the intestines of normal chickens (40 isolates) and chickens diagnosed as having colisepticemia (40 isolates) were compared. Differences were observed between the two groups for antibiotic resistance, siderophore production, presence of type 1 pili, complement resistance, motility, and size of plasmids. The systemic isolates were more likely to have siderophores and type 1 pili, and to be complement-resistant and motile than were the intestinal isolates. No differences between the two groups were observed for colicin production. Further comparison of the 10 most complement-resistant isolates from the systemic group and 10 most complement-sensitive isolates from the intestinal group revealed a correlation between an isolate's resistance to complement and its ability to kill embryos, express type 1 pili, and be motile. Virulence of avian E. coli strains appears to be correlated with complement resistance and the interaction of this resistance with the ability to produce type 1 pili and be motile.
Assuntos
Galinhas/microbiologia , Proteínas do Sistema Complemento/imunologia , Escherichia coli/patogenicidade , Animais , Antibacterianos/farmacologia , Galinhas/imunologia , Resistência Microbiana a Medicamentos , Escherichia coli/efeitos dos fármacos , Escherichia coli/imunologia , Infecções por Escherichia coli/imunologia , Infecções por Escherichia coli/veterinária , Doenças das Aves Domésticas/imunologia , Doenças das Aves Domésticas/microbiologia , VirulênciaRESUMO
A quantitative microtiter method for determining the degree of complement resistance or sensitivity of microorganisms is described. The microtiter method is compared with a quantitative automated system and the standard plate-count technique. Data were accumulated from 30 avian Escherichia coli isolates incubated at 35 C with either chicken plasma or heat-inactivated chicken plasma. Analysis of data generated by the automated system and plate-count techniques resulted in a classification of the microorganisms into three groups: those sensitive to the action of complement; those of intermediate sensitivity to the action of complement; and those resistant to the action of complement. Although the three methods studied did not agree absolutely, there were statistically significant correlations among them.