Environmental reservoirs for Serratia marcescens intramammary infections in dairy cows.

Via special media, Serratia marcescens isolates were found in 3 bedding pack samples and in 2 milking parlor floor samples, and in milk samples from 19 cows during an episode of mastitis in a dairy cow herd. Chromosomal digest patterns of isolated S marcescens were indistinguishable for 18 of the milk samples and all bedding pack samples. Our findings provide strong evidence that the bedding pack was the reservoir of S marcescens associated with the outbreak of intramammary infections. Additionally, our ability to match digest patterns of isolates in the bedding pack and milk confirms the theory that S marcescens is an environmental pathogen capable of causing mastitis.