Zoonotic bacteria and parasites found in raw meat-based diets for cats and dogs.

Feeding raw meat-based diets (RMBDs) to companion animals has become increasingly popular. Since these diets may be contaminated with bacteria and parasites, they may pose a risk to both animal and human health. The purpose of this study was to test for the presence of zoonotic bacterial and parasitic pathogens in Dutch commercial RMBDs. We analysed 35 commercial frozen RMBDs from eight different brands. Escherichia coli serotype O157:H7 was isolated from eight products (23 per cent) and extended-spectrum beta-lactamases-producing E coli was found in 28 products (80 per cent). Listeria monocytogenes was present in 19 products (54 per cent), other Listeria species in 15 products (43 per cent) and Salmonella species in seven products (20 per cent). Concerning parasites, four products (11 per cent) contained Sarcocystis cruzi and another four (11 per cent) S tenella In two products (6 per cent) Toxoplasma gondii was found. The results of this study demonstrate the presence of potential zoonotic pathogens in frozen RMBDs that may be a possible source of bacterial infections in pet animals and if transmitted pose a risk for human beings. If non-frozen meat is fed, parasitic infections are also possible. Pet owners should therefore be informed about the risks associated with feeding their animals RMBDs.

Bayesian estimation of diagnostic accuracy of a new bead-based antibody detection test to reveal Toxoplasma gondii infections in pig populations.

The success of a Toxoplasma gondii surveillance program in European pig production systems depends partly on the quality of the test to detect infection in the population. The test accuracy of a recently developed serological bead-based assay (BBA) was investigated earlier using sera from experimentally infected animals. In this study, the accuracy of the BBA was determined by the use of sera from animals from two field subpopulations. As no T. gondii infection information of these animals was available, test accuracy was determined through a Bayesian approach allowing for conditional dependency between BBA and an ELISA test. The priors for prevalence were based on available information from literature, whereas for specificity vague non-informative priors were used. Priors for sensitivity were based either on available information or specified as non-informative. Posterior estimates for BBA sensitivity and specificity were (mode) 0.855 (Bayesian 95% credibility interval (bCI) 0.702-0.960) and 0.913 (bCI 0.893-0.931), respectively. Comparing the results of BBA and ELISA, sensitivity was higher for the BBA while specificity was higher for ELISA. Alternative priors for the sensitivity affected posterior estimates for sensitivity of both BBA and ELISA, but not for specificity. Because the difference in prevalence between the two subpopulations is small, and the number of infected animals is small as well, the precision of the posterior estimates for sensitivity may be less accurate in comparison to the estimates for specificity. The estimated value for specificity of BBA is at least optimally defined for testing pigs from conventional and organic Dutch farms.

A novel bead-based assay to detect specific antibody responses against Toxoplasma gondii and Trichinella spiralis simultaneously in sera of experimentally infected swine.

BACKGROUND: A novel, bead-based flow cytometric assay was developed for simultaneous determination of antibody responses against Toxoplasma gondii and Trichinella spiralis in pig serum. This high throughput screening assay could be an alternative for well known indirect tests like ELISA. One of the advantages of a bead-based assay over ELISA is the possibility to determine multiple specific antibody responses per single sample run facilitated by a series of antigens coupled to identifiable bead-levels. Furthermore, inclusion of a non-coupled bead-level in the same run facilitates the determination of, and correction for non-specific binding. The performance of this bead-based assay was compared to one T. spiralis and three T. gondii ELISAs. For this purpose, sera from T. gondii and T. spiralis experimentally infected pigs were used. With the experimental infection status as gold standard, the area under the curve, Youden Index, sensitivity and specificity were determined through receiver operator curve analysis. Marginal homogeneity and inter-rater agreement between bead-based assay and ELISAs were evaluated using McNemar's Test and Cohen's kappa, respectively. RESULTS: Results indicated that the areas under the curve of the bead-based assay were 0.911 and 0.885 for T. gondii and T. spiralis, respectively, while that of the T. gondii ELISAs ranged between 0.837 and 0.930 and the T. spiralis ELISA was 0.879. Bead-based T. gondii assay had a sensitivity of 86% and specificity of 96%, while the ELISAs ranged between 64-84% and 93-99%, respectively. The bead-based T. spiralis assay had a sensitivity of 68% and specificity of 100% while the ELISA scored 72% and 95%, respectively. Marginal homogeneity was found between the T. gondii bead-based test and one of the T. gondii ELISAs. Moreover, in this test combination and between T. spiralis bead-based assay and respective ELISA, an excellent inter-rater agreement was found. When results of samples before expected seroconversion were removed from evaluation, notably higher test specifications were found. CONCLUSIONS: This new bead-based test, which detects T. gondii and T. spiralis antibodies simultaneously within each sample, can replace two indirect tests for the determination of respective antibodies separately, while performing equally well or better.

Immunochemical detection of Salmonella group B, D and E using an optical surface plasmon resonance biosensor.

A surface plasmon resonance biosensor (Biacore) was used to detect Salmonella through antibodies reacting with Salmonella group A, B, D and E (Kauffmann-White typing). In the assay designed, anti-Salmonella antibodies immobilized to the biosensor surface were allowed to bind injected bacteria followed by a pulse with soluble anti-Salmonella immunoglobulins to intensify the signal. No significant interference was found for (mixtures of) 30 non-Salmonella serovars at 10(9) CFU ml(-1). A total of 53 Salmonella serovars were successfully detected at 1 x 10(7) CFU ml(-1), except those of groups C, G, L and P, as expected. The cut-off point was determined with an equicellular mixture of Salmonella enteritidis and Salmonella typhimurium at a final amount of 1.7 x 10(3) CFU per test portion. Although further work is needed to cover the detection of all relevant Salmonella serovars in food-producing animals and food products, this work demonstrates the merits of this alternative biosensor approach in terms of automation, sensitivity, specificity, simple handling and limited hands-on time.