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
Source: PubMed


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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    • "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). "

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    • "The intestinal E. coli population of birds has previously been identified as an APEC reservoir [5], [9]. 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.
    PLoS ONE 06/2013; 8(6):e67749. DOI:10.1371/journal.pone.0067749 · 3.23 Impact Factor
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    • "Dozois et al. (2000) showed that the tsh gene is found more frequently in cases of high lethality of colibacillosis in chickens, ducks, and turkeys. However, other authors have detected a larger number of positive samples for the same gene in asymptomatic/healthy birds (Mcpeake et al. 2005). A study with faecal samples from symptomatic and asymptomatic chickens showed that the iss, tsh, and iuc genes were actually found at higher frequencies in clinical cases, although none could be classified as exclusively causing the disease, which suggests that other unknown virulence factors , together with environmental factors, may be involved in colibacillosis outbreaks (Vanderkerchove et al. 2005). "
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    ABSTRACT: Birds of the Cracidae family (curassows, guans, and chachalacas) are endemic of the Neotropics and 50 species are currently classified. Brazil has 22 species, seven of which are considered threatened. The Alagoas Curassow (Pauxi mitu) species is considered extinct in the wild; but about 120 birds are alive in captivity. Conservation of this species depends entirely on correct management. Health reports of both wildlife and captive curassows are rare. In this study the presence of Escherichia coli was evaluated in 23 healthy Alagoas Curassows from two private breeding centres. E. coli was isolated from cloacal swabs, and the presence of genes encoding cytotoxic necrotising factor 1 (cnf1), alpha-haemolysin (hly), aerobactin (iuc), serum resistance (iss) and the following adhesions: S fimbriae (sfa), pili associated with pyelonephritis (pap) and temperature-sensitive haemagglutinin (tsh) were investigated. E. coli was isolated from 78.3% (18/23) of the birds, and the percentage of curassows colonized by E. coli was similar between the two facilities. From the 22 E. coli isolates, 15 (68.2%) were positive for at least one virulence factor by PCR, and the most frequently found gene was iss (50%). No curassows had clinical signs of disease. Nevertheless, the presence of some E. coli strains may be a concern to the wildlife in captivity. Additional health surveillance studies are essential to guarantee successful conservation programmes for threatened cracids in Brazil.
    Pesquisa Veterinária Brasileira 04/2013; 33(4):523-527. DOI:10.1590/S0100-736X2013000400017 · 0.36 Impact Factor
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