Incidence of Salmonella Enteritidis in chicken layer flocks in Turkey: Results by real-time polymerase chain reaction and International Organization for Standardization culture methods

This study presents Salmonella Enteritidis incidence in chicken layer flocks in Turkey determined by real-time PCR (rPCR) and by International Organization for Standardization (ISO) method 6579:2002/Amd 1:2007. A total of 259 samples, composed of 1,036 individual samples each pooled into 4, including 175 cloacal swab, 14 intestine, 35 gizzard swab, and 35 cecal swab samples, belonging to 6 major companies, were collected from 50 layer flocks and tested by rPCR and ISO culture methods. Overall incidence of Salmonella in layer flocks by rPCR and culture was 61.0 and 55.6%, respectively, where 70.1% of these Salmonella isolates were determined as Salmonella Enteritidis. Incidences of Salmonella Enteritidis in culture-positive samples were 65.3% in cloacal swabs, 50.0% in intestines, 73.9% in gizzard swabs, and 87.5% in cecal swabs. The rPCR results were in 100% agreement (100% sensitivity and specificity) with culture results when cecal swabs were selected as the sample type. The relative accuracy of rPCR was 92.4, 91.4, and 84% for intestine, gizzard, and cloacal swab samples, respectively. As a result, by using rPCR and ISO culture, we determined that the Salmonella Enteritidis incidence in layer flocks in Turkey was high and that the use of cecal swab and intestine samples in Salmonella detection would yield reliable results. To reduce this high Salmonella Enteritidis incidence in layer flocks, Salmonella Enteritidis-specific vaccination should be implemented properly in conjunction with a well-designed biosecurity plan, including verifiable corrective actions.