Litter and aerosol sampling of chicken houses for rapid detection of Salmonella typhimurium contamination using gene amplification

Rapid screening of poultry houses for contamination is critical for Salmone lla control. Use of air filter sampling has great potential for efficient a nd reliable monitoring of Salmonella spp., as it could represent an entire poultry house and solve sample-size problems. Two sampling methods (litter and air filter) were compared for detection in four chicken pens inoculated with a S. typhimurium antibiotic resistant strain. Salmonella levels in bo th litter and air filter samples were determined by PCR amplification and b y conventional enrichment. Although amplified DNA was not directly detected , amplified DNA could be detected using a dual probe hybridization sensor. The ratio of the positive samples to total samples determined by gene ampli fication was much lower than that obtained by conventional enrichments (29/ 128 versus 102/728 samples). However, the ratio obtained by gene amplificat ion with air filter samples was greater than that with litter samples (26/6 4 versus 3/64). These results demonstrate that the air filter sampling meth od is an alternative method of Salmonella detection in poultry house using PCR gene amplification protocol.