Comparison of the Polymerase Chain Reaction Using Genus-Specific Oligonucleotide Primers and Microbiologic Culture for the Detection of Salmonella in Drag-Swabs from Poultry Houses

Drag-swab samples were collected from 18 poultry houses at 9 broiler farms. Fifty drag-swab samples were tested for Salmonella by microbiologic culture using selective enrichment and the polymerase chain reaction (PCR) with oligonucleotide primers specific for all members of the genus Salmonella. Drag-swab samples were tested for Salmonella using PCR before and after enrichment. Only one sample was positive by PCR prior to enrichment. Forty-seven of the drag-swabs samples tested after enrichment were positive for Salmonella using PCR, and 29 were positive by microbiologic culture. All but one of the culture-positive samples were positive by PCR; this discordant sample was classified as indeterminate by PCR. Salmonella was identified in houses from all nine farms by PCR and eight of nine farms by microbiologic culture. Salmonella was found in all 18 houses by PCR and in 15 of 18 houses by microbiologic culture. In this study, PCR was significantly (P < .001) more sensitive than culture for environmental monitoring of Salmonella using drag-swabs.