Effect of Fructooligosaccharide Metabolism on Chicken Colonization by an Extra-Intestinal Pathogenic Escherichia coli Strain

Extra-intestinal pathogenic Escherichia coli (ExPEC) strains cause many diseases in humans and animals. While remaining asymptomatic, they can colonize the intestine for subsequent extra-intestinal infection and dissemination in the environment. We have previously identified the fos locus, a gene cluster within a pathogenicity island of the avian ExPEC strain BEN2908, involved in the metabolism of short-chain fructooligosaccharides (scFOS). It is assumed that these sugars are metabolized by the probiotic bacteria of the microbiota present in the intestine, leading to a decrease in the pathogenic bacterial population. However, we have previously shown that scFOS metabolism helps BEN2908 to colonize the intestine, its reservoir. As the fos locus is located on a pathogenicity island, one aim of this study was to investigate a possible role of this locus in the virulence of the strain for chicken. We thus analysed fos gene expression in extracts of target organs of avian colibacillosis and performed a virulence assay in chickens. Moreover, in order to understand the involvement of the fos locus in intestinal colonization, we monitored the expression of fos genes and their implication in the growth ability of the strain in intestinal extracts of chicken. We also performed intestinal colonization assays in axenic and Specific Pathogen-Free (SPF) chickens. We demonstrated that the fos locus is not involved in the virulence of BEN2908 for chickens and is strongly involved in axenic chicken cecal colonization both in vitro and in vivo. However, even if the presence of a microbiota does not inhibit the growth advantage of BEN2908 in ceca in vitro, overall, growth of the strain is not favoured in the ceca of SPF chickens. These findings indicate that scFOS metabolism by an ExPEC strain can contribute to its fitness in ceca but this benefit is fully dependent on the bacteria present in the microbiota

Identification of Novel Pathogenicity Loci in Clostridium perfringens Strains That Cause Avian Necrotic Enteritis

Type A Clostridium perfringens causes poultry necrotic enteritis (NE), an enteric disease of considerable economic importance, yet can also exist as a member of the normal intestinal microbiota. A recently discovered pore-forming toxin, NetB, is associated with pathogenesis in most, but not all, NE isolates. This finding suggested that NE-causing strains may possess other virulence gene(s) not present in commensal type A isolates. We used high-throughput sequencing (HTS) technologies to generate draft genome sequences of seven unrelated C. perfringens poultry NE isolates and one isolate from a healthy bird, and identified additional novel NE-associated genes by comparison with nine publicly available reference genomes. Thirty-one open reading frames (ORFs) were unique to all NE strains and formed the basis for three highly conserved NE-associated loci that we designated NELoc-1 (42 kb), NELoc-2 (11.2 kb) and NELoc-3 (5.6 kb). The largest locus, NELoc-1, consisted of netB and 36 additional genes, including those predicted to encode two leukocidins, an internalin-like protein and a ricin-domain protein. Pulsed-field gel electrophoresis (PFGE) and Southern blotting revealed that the NE strains each carried 2 to 5 large plasmids, and that NELoc-1 and -3 were localized on distinct plasmids of sizes ∼85 and ∼70 kb, respectively. Sequencing of the regions flanking these loci revealed similarity to previously characterized conjugative plasmids of C. perfringens. These results provide significant insight into the pathogenetic basis of poultry NE and are the first to demonstrate that netB resides in a large, plasmid-encoded locus. Our findings strongly suggest that poultry NE is caused by several novel virulence factors, whose genes are clustered on discrete pathogenicity loci, some of which are plasmid-borne

Aislamientos de cepas fúngicas con capacidad de producción de enzimas ligninolíticas

XIII Congreso argentino de microbiología,II Congreso de microbiología agrícola y ambiental;2013Peer Reviewe

Inhibitory effects of Lactobacilli on enteropathogenic Salmonella

The major source of human salmonellosis are farm animals, which may frequently be intestinal carriers of the organism. Lactobacilli isolated from the intestinal tract with efficiency adhesion were selected and studied in assay competitions with different Salmonella serotypes. The growth and lectin production of lactobacilli remained unchanged in several mixed and single culture studies. However, in mixed cultures, the inhibition (bacteriostatic) of viable bacteria of salmonella strains was observed. The adhesion ratio showed significant values for L. animalis, L. fermentum, S. Gallinarum and S. Pullorum. These results indicate the remarkable importance of a specific host interaction in the colonization process by microorganisms. L. animalis was effective in reducing the attachment of S. Gallinarum, S. Pullorum and S. Enteritidis to host-specific epithelial cells, while L. fermentum was able to reduce the attachment of S. Pullorum and S. Gallinarum. Therefore, we suggest that chicken lactobacilli included in this work may be considered potential probiotic microorganisms, and used in the preparation of a probiotic food.Fil: Gusils Leon, Carlos Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ross, Gloria Romina. Universidad Nacional de Tucuman. Facultad de Bioquímica, Química y Farmacia. Instituto de Farmacia. Cátedra de Salud Publica; ArgentinaFil: Draksler, Diana. Universidad Nacional de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Pérez, C. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas; ArgentinaFil: Tous, M. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentin

Immunological evaluation of the intestinal mucosa of broiler chicks treated with Lactobacillus Spp. and challenged with Salmonella Enteritidis

This study aimed at the antibody production by intestinal mucosa of broilers chicks were orally inoculated with Lactobacillus spp. at one and/or 21 days of age, and subsequently challenged with Salmonella enterica, subspecies enterica, serotype Enteritidis (S. Enteritidis). A total number of 288 drug-free broiler chicks was divided into 6 groups (groups A, B, C, D, E, and F), according to age at Lactobacillus spp. inoculation and SE challenge. The intestinal mucosa immune response was determined as the production of immunoglobulin A against S. Enteritidis, and evaluated by the Enzyme-Linked Immunosorbent Assay (ELISA) technique in intestinal washing fluid. Groups treated with Lactobacillus spp. presented higher IgA production only when the chicks were challenged with S. Enteritidis at 21 days of age. Nevertheless, the expected stimulus for intestinal mucosa antibody production induced by Lactobacillus spp was observed in only some of the treated groups, demonstrating that the protocol utilized in the present experiment resulted in few beneficial effects for chicks, particularly during the first days of life

Percent G+C Profiling Accurately Reveals Diet-Related Differences in the Gastrointestinal Microbial Community of Broiler Chickens

Broiler chickens from eight commercial farms in Southern Finland were analyzed for the structure of their gastrointestinal microbial community by a nonselective DNA-based method, percent G+C-based profiling. The bacteriological impact of the feed source and in-farm whole-wheat amendment of the diet was assessed by percent G+C profiling. Also, a phylogenetic 16S rRNA gene (rDNA)-based study was carried out to aid in interpretation of the percent G+C profiles. This survey showed that most of the 16S rDNA sequences found could not be assigned to any previously known bacterial genus or they represented an unknown species of one of the taxonomically heterogeneous genera, such as Ruminococcus or Clostridium. The data from bacterial community profiling were analyzed by t-test, multiple linear regression, and principal-component statistical approaches. The percent G+C profiling method with appropriate statistical analyses detected microbial community differences smaller than 10% within each 5% increment of the percent G+C profiles. Diet turned out to be the strongest determinant of the cecal bacterial community structure. Both the source of feed and local feed amendment changed the bacteriological profile significantly, whereas profiles of individual farms with identical feed regimens hardly differed from each other. This suggests that the management of typical Finnish farms is relatively uniform or that hygiene on the farm, in fact, has little impact on the structure of the cecal bacterial community. Therefore, feed compounders should have a significant role in the modulation of gut microflora and consequently in prevention of gastrointestinal disorders in farm animals