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Avian intestinal spirochaetosis (AIS) caused by Brachyspira spp., and notably Brachyspira pilosicoli, is common in layer flocks and reportedly of increasing incidence in broilers and broiler breeders. Disease manifests as diarrhoea, increased feed consumption, reduced growth rates and occasional mortality in broilers and these signs are shown in layers also associated with a delayed onset of lay, reduced egg weights, faecal staining of eggshells and non-productive ovaries. Treatment with Denagard® Tiamulin has been used to protect against B. pilosicoli colonisation, persistence and clinical presentation of AIS in commercial layers, but to date there has been no definitive study validating efficacy. Here, we used a poultry model of B. pilosicoli infection of layers to compare the impact of three doses of Denagard® Tiamulin. Four groups of thirty 17 week old commercial pre-lay birds were all challenged with B. pilosicoli strain B2904 with three oral doses two days apart. All birds were colonised within 2 days after the final oral challenge and mild onset of clinical signs were observed thereafter. A fifth group that was unchallenged and untreated was also included for comparison as healthy birds. Five days after the final oral Brachypira challenge three groups were given Denagard® Tiamulin in drinking water made up following the manufacturer's recommendations with doses verified as 58.7 ppm, 113 ppm and 225 ppm. Weight gain body condition and the level of diarrhoea of birds infected with B. pilosicoli were improved and shedding of the organism reduced significantly (p=0.001) following treatment with Denagard® Tiamulin irrespective of dose given. The level and duration of colonisation of organs of birds infected with B. pilosicoli was also reduced. Confirming previous findings we showed that the ileum, caeca, colon, and both liver and spleen were colonised and here we demonstrated that treatment with Denagard® Tiamulin resulted in significant reduction in the numbers of Brachyspira found in each of these sites and dramatic reduction in faecal shedding (p<0.001) to approaching zero as assessed by culture of cloacal swabs. Although the number of eggs produced per bird and the level of eggshell staining appeared unaffected, egg weights of treated birds were greater than those of untreated birds for a period of approximately two weeks following treatment. These data conclusively demonstrate the effectiveness of Denagard® Tiamulin in reducing B. pilosicoli infection in laying hens., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Strangles is one of the most common equine infectious diseases with serious health, welfare and socio-economic impact. However, the detection of Streptococcus equi subspecies equi can be challenging and persistently infected carriers are common. Furthermore, the use of classical microbiology can result in an underestimation of the prevalence of the disease. The difficulties associated with the slow diagnosis of Strangles can result in rapid spread of the disease. Therefore, rapid and economical diagnostic tests are urgently required. Here, two multiplex assays, were developed and validated for the detection of S. equi and S. equi subspecies zooepidemicus, the most common differential diagnosis. Using 59 S. equi and 59 S. zooepidemicus strains collected from various geographical areas, the PCR tests demonstrated a sensitivity of 95% and a specificity of 98%. Furthermore, the assay can be performed directly from clinical swabs. Thus, the assays designed here provide a rapid, reliable and economical solution for the diagnosis of Strangles., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Enteric bacteria with resistance to third and fourth generation cephalosporin antibiotics, especially Escherichia coli bearing the blaCTX-M gene, have been detected in a wide range of food producing animals. However, commercial vaccines for these organisms are not currently available. An autogenous vaccine was prepared from E. coli bearing the blaCTX-M-14 gene and evaluated as a potential control measure to reduce shedding and dissemination of these organisms in cattle. Calves (n=30) received either an autogenous vaccine prepared from E. coli serotype O33 bearing the blaCTX-M-14 gene or a placebo by intramuscular injection on three separate occasions. Two weeks after the final vaccination, all calves were challenged by oral gavage with the O33 CTX-M-14 strain of E. coli (1×10(10) CFU). Faeces, intestinal mucosa and blood samples were taken for enumeration of total and CTX-M-14 E. coli and for assessment of the humoral immune response. The cumulative number of total E. coli excreted at 7 days post-challenge was significantly (p=0.006) lower in the vaccinated group than the placebo group. However, there was no significant difference in the shedding of either CTX-M-14 E. coli or total E. coli between vaccinated and placebo calves throughout the study period. The systemic immune response to E. coli O33 antigen was tested by ELISA and was significantly higher (p<0.001) in vaccinated than placebo calves. However, there was no significant difference in the mucosal immune response. These findings do not support the use of autogenous vaccination for the control of CTX-M-14 E. coli in calves., (Crown Copyright © 2013. Published by Elsevier India Pvt Ltd. All rights reserved.)

Escherichia coli O115 has been isolated from healthy sheep and was shown to be associated with attaching-effacing (AE) lesions in the large intestine. Following previous observations of interactions between E. coli O157 and O26, the aim of the present study was to assess what influence an O115 AE E. coli (AEEC) would have on E. coli O157 colonisation in vitro and in vivo. We report that E. coli O115- and O157-associated AE lesions were observed on HEp-2 cells and on the mucosa of ligated ovine spiral colon. In single strain inoculum, E. coli O115 associated intimately with HEp-2 cells and the spiral colon in greater numbers than E. coli O157:H7. However, in mixed inoculum studies, the number of E. coli O115 AE lesions was significantly reduced suggesting negative interference by E. coli O157. Use of the ligated colon model in the present work has allowed in vitro observations to be extended and confirmed whilst using a minimum of experimental animals. The findings support a hypothesis that some AEEC can inhibit adhesion of other AEEC in vivo. The mechanisms involved may prove to be of utility in the control of AE pathovars., (Crown Copyright © 2011. Published by Elsevier India Pvt Ltd. All rights reserved.)

Recent surveys have shown that Escherichia coli O26 is prevalent in ruminants compared with E. coli O157. These serogroups share common colonisation factors and we hypothesised that prior colonisation by E. coli O26 may show reduced colonisation by E. coli O157. To test this hypothesis, strains of E. coli O26:K60 and O157:H7 were tested in competitive in vitro and in vivo studies. Using an established 6-week-old lamb model, an experimental group of lambs was dosed orally with E. coli O26:K60 and then E. coli O157:H7 four days later. The faecal shedding of O26:K60 and O157:H7 organisms from this experimental group was compared with that from animals dosed with either O26:K60 alone or O157:H7 alone. Shedding data indicated that counts for O157:H7 were unaffected by the competition from O26:K60, whereas the O26:K60 counts were lower when competing with O157:H7.

Escherichia fergusonii has been associated with a wide variety of intestinal and extra-intestinal infections in both humans and animals but, despite strong circumstantial evidence, the degree to which the organism is responsible for the pathologies identified remains uncertain. Thirty isolates of E. fergusonii collected between 2003 and 2004 were screened using an Escherichia coli virulence gene array to test for the presence of homologous virulence genes in E. fergusonii. The iss (increased serum survival) gene was present in 13/30 (43%) of the test strains and the prfB (P-related fimbriae regulatory) and ireA (siderophore receptor IreA) genes were also detected jointly in 3/30 (10%) strains. No known virulence genes were detected in 14/30 (47%) of strains. Following confirmatory PCR and sequence analysis, the E. fergusoniiprfB, iss and ireA genes shared a high degree of sequence similarity to their counterparts in E. coli, and a particular resemblance was noted with the E. coli strain APEC O1 pathogenicity island. In tissue culture adherence assays, nine E. fergusonii isolates associated with HEp-2 cells with a 'localised adherence' or 'diffuse adherence' phenotype, and they proved to be moderately invasive. The E. fergusonii isolates in this study possess both some phenotypic and genotypic features linked to known pathotypes of E. coli, and support existing evidence that strains of E. fergusonii may act as an opportunistic pathogens, although their specific virulence factors may need to be explored.

In a series of experiments involving the inoculation of sheep with Escherichia coli O157:H7, and subsequent detailed histopathological examination of the intestinal mucosa, attaching-effacing (AE) lesions formed by elements of the natural flora were observed in 18% of animals. These incidental AE lesions typically were small and sparse, and were not associated with clinical disease. It was possible to identify further some of the lesional bacteria, revealing that E. coli O115 had formed lesions in one of the seven affected animals, and similarly E. coli O26 had formed some of the lesions in another. As AE strains, source flocks, housing and feed sources were diverse, a common source of lesion-forming bacteria appears to be unlikely. It is postulated that subclinical AE lesions are a mechanism of persistence of AE bacteria in sheep.

The current understanding of the pathogenesis of avian pathogenic Escherichia coli (APEC) in colisepticaemia is limited. This review discusses putative virulence determinants per se, such as a number of surface organelles including fimbriae and flagella; together with other factors such as iron sequestering mechanisms, which are involved in the survival of E. coli in the host rather than initiation of infection. It is concluded that avian colisepticaemia is a multi-factorial disease and that to date only a limited number of virulence factors of APEC have been thoroughly elucidated.