Adhesion properties, fimbrial expression and PCR detection of adhesin-related genes of avian Escherichia coli strains.
Forty-nine avian pathogenic Escherichia coli (APEC) strains obtained from chickens suffering from septicemia (24), swollen head syndrome (14) and omphalitis (11), isolated from individuals in different regions of Brazil and from different outbreaks, were studied for their adhesion to trachea epithelial cells, fimbrial expression and hemagglutination capacity to different erythrocyte types. These results were compared with their content of fimbriae-related genes as detected by polymerase chain reaction (PCR) using specific pair of primers. The aim of these assays was to determine the importance of expression of adhesins in the pathogenic strains and to evaluate the presence of adhesin genes either previously described or not yet recognized for APEC strain. Thirty commensal strains isolated from poultry showing no signs of any of the above diseases were used to compare the results with the pathogenic isolates. The PCR assay demonstrated that septicaemic and swollen head syndrome strains had the highest number of adhesion-related genes of recognized importance in pathogenicity. Using different media for growth conditions, 40 different D-mannose resistant haemagglutination patterns were observed in this study, what indicates the expression of a great variability of surface agglutinins in these bacterial strains. Our results also showed that adhesion, whether D-mannose resistant (MRA) or D-mannose sensitive (MSA), is a characteristic observed in both pathogenic and commensal strains. Several strains with positive adherence had no genetic sequences related to the studied adhesin genes what indicates that our APEC strains probably possess a genome with adhesins genes besides those describe elsewhere and that have not yet been described.
Amabile de Campos
Tatiana
T
Department of Microbiology and Immunology, Biology Institute, CP 6109, Campinas State University-UNICAMP, Campinas, São Paulo, Brazil.
Stehling
Eliana Guedes
EG
Ferreira
Alessandra
A
Pestana de Castro
Antonio Fernando
AF
Brocchi
Marcelo
M
Dias da Silveira
Wanderley
W
D018830:Adhesins, Escherichia coli / Q000235:genetics; D000818:Animals; D001422:Bacterial Adhesion / Q000235:genetics; D002645:Chickens / Q000382:microbiology*; D004848:Epithelium / Q000382:microbiology; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D010861:Fimbriae, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D006384:Hemagglutination; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011201:Poultry Diseases / Q000382:microbiology*; D014132:Trachea / Q000382:microbiology
D018830:Adhesins, Escherichia coli