Draft Genome Sequences of Two Strains of Salmonella enterica Serovar Typhimurium Displaying Different Virulence in an Experimental Chicken Model.

Salmonella enterica serovar Typhimurium strains 22495 and 22792, obtained from wild birds, were found to display different virulence attributes in an experimental chicken model. Closed genome sequences were assembled after sequencing with the Roche 454 and Illumina MiSeq platforms. An additional plasmid was present in the more virulent strain 22495.

Comparison of an antigen-capture enzyme-linked immunosorbent assay with bacterial culture for detection of Salmonella in poultry-hatchery environmental samples.

An antigen-capture, monoclonal-antibody-based enzyme-linked immunoassay (ELISA) that detects a broad range of Salmonella serovars in various serogroups was developed and compared with standard culture procedures for detection of Salmonella in 1055 field samples collected from poultry-hatchery environments. The diagnostic sensitivity of the ELISA relative to culture was 99.9% and the diagnostic specificity 99.6%. The extensive culture procedure included nonselective enrichment (NSE) as well as primary selective enrichment (PSE) and delayed secondary enrichment (DSE) with Hajna tetrathionate (TT) and Rappaport-Vassiliadis (RV) selective-enrichment broths. Significantly more Salmonella-positive samples were detected by ELISA and culture at the DSE stage than at the NSE and PSE stages (P < 0.05). Significantly more RV than TT broths were positive for Salmonella by culture and ELISA by the DSE stage (P < 0.05). This ELISA procedure could be a reliable screening test for the detection of Salmonella in hatchery samples.

Une épreuve immuno-enzymatique de capture d'antigène utilisant un anticorps monoclonal détectant un grand nombre de sérovars de Salmonella dans différents sérogroupes a été développée et comparée aux procédures standards de culture pour la détection de Salmonella dans 1055 échantillons prélevés de l'environnement de couvoirs de poulet. La sensibilité diagnostique de l'ELISA comparativement à la culture était de 99,9% et la spécificité diagnostique 99,6%. La procédure de culture incluait un enrichissement non-sélectif (NSE) ainsi qu'un enrichissement primaire sélectif (PSE) et un enrichissement secondaire retardé (DSE) avec les bouillons d'enrichissement sélectifs Hajna tétrathionate (TT) et Rappaport-Vassiliadis (RV). Un nombre significativement plus élevé d'échantillons positifs pour Salmonella fut détecté par ELISA et culture au stade DSE qu'aux stades NSE et PSE (P < 0,05). Un nombre significativement plus grand de bouillons RV que de bouillons TT était positif pour Salmonella par culture et ELISA au stade DES (P < 0,05). Cette procédure ELISA pourrait être une épreuve de tamisage rapide et fiable pour la détection de Salmonella dans les échantillons provenant de couvoirs.(Traduit par Docteur Serge Messier).

Development of an antigen-capture monoclonal antibody-based enzyme-linked immunosorbent assay and comparison with culture for detection of Salmonella enterica serovar Enteritidis in poultry hatchery environmental samples.

An antigen-capture enzyme-linked immunosorbent assay (ELISA) was developed for use as a presumptive screening test for detection of Salmonella enterica serovar Enteritidis and other group D Salmonella in poultry hatchery environments. A mixture of 2 monoclonal antibodies that recognize different forms of the lipopolysaccharide O-antigen was used for specific detection of group D Salmonella. The performance of the ELISA was evaluated in comparison to standard Salmonella culture procedures. Culture for each sample included nonselective enrichment with buffered peptone water and primary selective enrichment and delayed secondary enrichment with both tetrathionate and Rappaport-Vassiliadis broths. One thousand fifty-seven samples were collected from poultry hatcheries over a 5-year period (received in 85 submissions), and S. Enteritidis was recovered from 106 (10%) of them. The diagnostic sensitivity and specificity of the ELISA relative to culture were 97.2% and 99.6%, respectively, on a sample basis and were both 100% on a submission basis. Delayed secondary enrichment increased the number of S. Enteritidis culture and ELISA-positive samples as compared to nonselective enrichment and primary selective enrichment by 25%. A significantly higher (P < 0.05) number of S. Enteritidis culture- and ELISA-positive results were obtained from Rappaport-Vassiliadis broth than from tetrathionate broth or buffered peptone water cultures. The results indicate that this ELISA procedure may be useful for screening poultry hatchery environmental samples for the presence of S. Enteritidis.