CONICET | Buscador de Institutos y Recursos Humanos

The performance of detection methods(culture methods and polymerase chain reaction assay)and plating media used in the same type of sampleswere determined as well as the specificity of PCRprimers to detected Salmonella spp. contamination inlayer hen farms. Also, the association of farm characteristicswith Salmonella presence was evaluated. Environmentalsamples (feces, feed, drinking water, air, bootswabs)and eggs were taken from 40 layer hen houses.Salmonella spp. was most detected in boot-swabs takenaround the houses (30% and 35% by isolation and PCR,respectively) follow by fecal samples (15.2% and 13.6%by isolation and PCR, respectively). Eggs, drinking water,and air samples were negative for Salmonella detection.Salmonella Schwarzengrund and S. Enteritidiswere the most isolated serotypes. For plating media, relativespecificity was 1, and the relative sensitivity wasgreater for EF-18 agar than XLDT agar in feed andfecal samples. However, relative sensitivity was greaterin XLDT agar than EF-18 agar for boot-swab samples.Agreement was between fair to good depending on thesample, and it was good between isolation and PCR (fecesand boot-swabs), without agreement for feed samples.Salmonella spp. PCR was positive for all strains,while S. Typhimurium PCR was negative. SalmonellaEnteritidis PCR used was not specific. Based in themultiple logistic regression analyses, categorization bycounties was significant for Salmonella spp. presence(P-value = 0.010). This study shows the importanceof considering different types of samples, plating mediaand detection methods during a Salmonella spp. monitoringstudy. In addition, it is important to incorporatethe sampling of floors around the layer hen houses tolearn if biosecurity measures should be strengthenedto minimize the entry and spread of Salmonella in thehouses. Also, the performance of some PCR methodsand S. Enteritidis PCR should be improved, and biosecuritymeasures in hen farms must be reinforced in theregion of more concentrated layer hen houses to reducethe probability of Salmonella spp. presence.