Characterisation of avian pathogenic E. coli (APEC) associated with colisepticaemia compared to faecal isolates from healthy birds
Queen's University Belfast, Béal Feirste, Northern Ireland, United Kingdom Veterinary Microbiology
(Impact Factor: 2.51).
11/2005; 110(3-4):245-53. DOI: 10.1016/j.vetmic.2005.08.001
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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- "In the present study, virulence genotyping of E. coli isolates recovered from broiler chickens revealed the presence of uidA gene (468 bp fragment) in all field isolates (6 serovars) examined in an incidence of 100%. The result concerning the cvaC gene indicated its presence in all field isolates (6 serovars) in an incidence of 97.14% as shown in Table 2. OnlyMcpeake et al. (2005)found similar results (99.1%), while other authors obtained a lower percent- age.Blanco et al. (1997)reported 22% andSiek et al. (2005)reported 66.8%. It is clear from the obtained result that cvaC gene showed the highest percentage (97.14%), "
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ABSTRACT: The current study was carried out to evaluate the phenotypic and genotypic characterization of avian pathogenic Escherichia coli recovered from Riyadh, Saudi Arabia. During the period of 10th February to 30th May 2015, 70 E. coli strains were isolated from chicken farms located in Riyadh, Saudi Arabia. All the strains were tested by phenotypically by standard microbiological techniques, serotyped and the virulence genes of such strains were detected by polymerase chain reaction (PCR). Most of the recovered strains from chickens belonged to serotype O111: K58 25 strains (35.7%), followed by serotype O157: H7 13 strains (18.57%), followed by serotype O114: K90 10 strains (14.29%), then serotype O126:K71 9 strains (12.9%), serotype O78: K80 8 strains (11.43%) and in lower percentage serotype O114: K90 and O119: K69 5 strains (7.14%). The virulence genotyping of E. coli isolates recovered from broilers revealed the presence of uidA gene in all of the field isolates (6 serovars) examined in an incidence of 100%, as well as cvaC gene was present also in all of the field isolates (6 serovars). While iutA gene and iss gene were detected in 5 out of 6 field serovars in incidence of 81.43% and 64.29%, respectively. Phenotypical examination of the other virulence factors revealed that 65 isolates were hemolytic (92.9%), as well as 15 isolates (21.42%) were positive for enterotoxin production. Meanwhile, 21 isolates (30%) were positive for verotoxin production, 58 isolates (82.86%) for the invasiveness and 31 isolates (44.29%) for Congo red binding activities of the examined serotypes.
Available from: Ionica Iancu
- "After that, the interpretation was carried out (Barnes et al. 2003). The fixing of the red Congo dye was made on TSA agar (Trypticase Soy Agar), with an additional 0,15% biliary salts and 0,03% dye, the inseminations having been made through exhaustion, with the bacteriological dowser, in order to obtain isolated colonies (McPeake et al 2005, Rodriguez et al. 2005). 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 (Ewers et al. 2003). "
Available from: Paul Wigley
- "The intestinal E. coli population of birds has previously been identified as an APEC reservoir , . The findings from this study further support this with 36.4–80.0% of systemic VAG profiles also being identified among faecal E. coli of the same flock. "
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ABSTRACT: Colibacillosis is an economically important syndromic disease of poultry caused by extra-intestinal avian pathogenic Escherichia coli (APEC) but the pathotype remains poorly defined. Combinations of virulence-associated genes (VAGs) have aided APEC identification. The intestinal microbiota is a potential APEC reservoir. Broiler chickens are selectively bred for fast, uniform growth. Here we simultaneously investigate intestinal E. coli VAG carriage in apparently healthy birds and characterise systemic E. coli from diseased broiler chickens from the same flocks. Four flocks were sampled longitudinally from chick placement until slaughter. Phylogrouping, macro-restriction pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) were performed on an isolate subset from one flock to investigate the population structure of faecal and systemic E. coli. Early in production, VAG carriage among chick intestinal E. coli populations was diverse (average Simpson's D value = 0.73); 24.05% of intestinal E. coli (n = 160) from 1 day old chicks were carrying ≥5 VAGs. Generalised Linear models demonstrated VAG prevalence in potential APEC populations declined with age; 1% of E. coli carrying ≥5 VAGs at slaughter and demonstrated high strain diversity. A variety of VAG profiles and high strain diversity were observed among systemic E. coli. Thirty three new MLST sequence types were identified among 50 isolates and a new sequence type representing 22.2% (ST-2999) of the systemic population was found, differing from the pre-defined pathogenic ST-117 at a single locus. For the first time, this study takes a longitudinal approach to unravelling the APEC paradigm. Our findings, supported by other studies, highlight the difficulty in defining the APEC pathotype. Here we report a high genetic diversity among systemic E. coli between and within diseased broilers, harbouring diverse VAG profiles rather than single and/or highly related pathogenic clones suggesting host susceptibility in broilers plays an important role in APEC pathogenesis.
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