Detection of virulence-associated genes in pathogenic and commensal avian Escherichia coli isolates.

Poultry colibacillosis due to Avian Pathogenic Escherichia coli (APEC) is responsible for several extra-intestinal pathological conditions, leading to serious economic damage in poultry production. The most commonly associated pathologies are airsacculitis, colisepticemia, and cellulitis in broiler chickens, and salpingitis and peritonitis in broiler breeders. In this work a total of 66 strains isolated from dead broiler breeders affected with colibacillosis and 61 strains from healthy broilers were studied. Strains from broiler breeders were typified with serogroups O2, O18, and O78, which are mainly associated with disease. The serogroup O78 was the most prevalent (58%). All the strains were checked for the presence of 11 virulence genes: 1) arginine succinyltransferase A (astA); ii) E.coli hemeutilization protein A (chuA); iii) colicin V A/B (cvaA/B); iv) fimbriae mannose-binding type 1 (fimC); v) ferric yersiniabactin uptake A (fyuA); vi) iron-repressible high-molecular-weight proteins 2 (irp2); vii) increased serum survival (iss); viii) iron-uptake systems of E.coli D (iucD); ix) pielonefritis associated to pili C (papC); x) temperature sensitive haemaglutinin (tsh), and xi) vacuolating autotransporter toxin (vat), by Multiplex-PCR. The results showed that all genes are present in both commensal and pathogenic E. coli strains. The iron uptake-related genes and the serum survival gene were more prevalent among APEC. The adhesin genes, except tsh, and the toxin genes, except astA, were also more prevalent among APEC isolates. Except for astA and tsh, APEC strains harbored the majority of the virulence-associated genes studied and fimC was the most prevalent gene, detected in 96.97 and 88.52% of APEC and AFEC strains, respectively. Possession of more than one iron transport system seems to play an important role on APEC survival.

Genomic and proteomic evaluation of antibiotic resistance in Salmonella strains.

Using Salmonella strains identical to those present in the gastrointestinal tract of different animals we aim to determine and compare the proteome of two serotypes, Salmonella Typhimurium and Enteritidis recovered from faecal samples of wild boars and wild rabbits, respectively. The presence of genes responsible for antibiotic resistance was detected by PCR. Proteomes of the two distinct serotypes were determined using 2-DE in order to identify proteins associated with antibiotic resistance or virulence. Through 2-DE we obtained a total of 229 spots from both strains. All were suitable for MALDI-TOF/TOF and, in correlation with bioinformatic databases, allowed accurate identification and characterization of proteins. S. Enteritidis recovered from wild rabbits was sensitive to all the antibiotics tested in contrast to S. Typhimurium isolated from wild boars which presented a resistance phenotype to ampicillin, streptomycin and chloramphenicol. Nevertheless, despite the different ratio of proteins observed in each proteome according to their biological function, no significant difference was observed in the involvement of these proteins in pathogenicity. Bearing in mind that serotypes are related to infectious processes in humans and animals, it is important to explore the proteome of new strains which might serve as protein biomarkers for biological activity.