Characterisation of avian pathogenic Escherichia coli (APEC) associated with colisepticaemia compared to faecal isolates from healthy birds.
ABSTRACT A total of 114 avian pathogenic Escherichia coli (APEC) isolates were collected from cases of colisepticaemia occurring in broilers (77) and layers (37) within Ireland. In addition 45 strains isolated from faeces of healthy birds were included for comparison. All isolates were serogrouped, and examined for known virulence factors, mostly by PCR. The O78 serogroup represented 55 and 27% of broiler and layer colisepticaemic isolates respectively. All isolates were positive for curli fimbriae (crl, csg) and negative for afimbrial adhesin (afa). S-fimbrial (sfa) sequences were present in 8.8% of septicaemic isolates and 8.9% of healthy bird isolates. The majority of E. coli from cases of colisepticaemia (97.4%) and healthy bird (95.6%) isolates were positive for aerobactin (aer), and temperature sensitive haemagglutinin (tsh) was similarly detected in high numbers in 93.9 and 93.3%, respectively. In comparison to E. coli isolates from the faeces of healthy birds, a significantly higher percentage of isolates from septicaemic cases possessed Type 1 fimbriae (fimC) and increased serum survival (iss) gene sequences. Forty-seven (41.2%) isolates from septicaemic birds possessed P-fimbriae (pap) gene sequences, compared with only 15.6% from E. coli isolated from healthy birds. Haemolysin (hlyE) sequences were detected in 46.7% of isolates from healthy birds in comparison with 6.1% of septicaemic isolates. Sequences encoding colicin V (cvaC) were detected in 99.1% of septicaemic isolates and 82.2% of isolates from healthy birds. The K1 capsule was only present in two septicaemic isolates, both taken from layers. Motility was detected in 36.8% of E. coli isolated from cases of septicaemia, compared with 93.3% of isolates from healthy birds. These results demonstrate the presence of 11 virulence genes in E. coli isolated from cases of colisepticaemia within Ireland, and indicate the prevalence of iss and fimC.
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ABSTRACT: Research has been performed on a total of 121 E. coli strains isolated from broilers corpses of different ages with lesions of colisepticaemia. Classification of strains in APEC pathotype was realized by identifying genes OmpA, iss and fimH by the multiplex PCR technique. The binding of Congo Red was tested on TSA agar. The epidemiological marker followed, respectively the binding of Congo Red, was present in 112 strains, respectively 92.56% of the strains tested. Multiplex PCR technique has allowed detection of the genes OmpA, iss and fimH, which generates the synthesis of some virulence factors specific to APEC strains, in 118 of the strains tested, respectively 97.52%. APEC pathotype (Avian Pathogenic Escherichia coli) includes pathogenic strains for birds, causing extraintestinal infections of septicemic type, starting from the respiratory mucosa. Overwhelming majority of the strains classified in this pathotype is serogroup O78 and binding of Congo Red is an epidemiological marker that can be used for discrimination of pathogenic strains from the commensal ones, especially in the serogroup O78 (1, 2).
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ABSTRACT: Colisepticaemia is a frequently disease of poultry caused by Escherichia coli. The researches have been performed on 128 strains of E. coli isolated from broilers with different ages, from five farms, and from the shed air, only from one farm. The strains have been identified according to their biochemical characters, and then we have tested their hemolytic activity on agar with 5% sheep defibrined blood, fixed the Congo Red in agar TSA and the profile of resistance to antibiotics. This study was to confirm the association between Congo Red binding E coli and colisepticaemia in commercial broilers.
Dataset: Lucrare Cluj 2010