Aerosol route enhances the contamination of intact eggs and muscle of experimentally infected laying hens by Salmonella typhimurium DT104

Commercial laying hens were infected with Salmonella typhimurium DT104 strain 16 alternatively via the crop (10⁷ cfu per bird) or by an aerosol delivered directly to the beaks using a Collison nebuliser and Henderson apparatus (2 X 10² or 2 X 10⁴ cfu per bird). Infection by both routes caused systemic infection and prolonged contamination of faeces. Contamination rates of eggs and muscle were much higher following the aerosol challenges despite the much lower doses given by this route. The frequency of Salmonella isolation from eggs rose from 1.7% following oral challenge to 14% and 25%, for each of the aerosol challenges respectively, and the frequency of isolation from muscle rose from 0% following the oral challenge to 27% following each of the aerosol challenges.