Efficacy of washing and sanitizing trailers used for swine transport in reduction of Salmonella and Escherichia coli.

Healthy pigs can carry Salmonella in their intestine and may shed this pathogen because of stresses incurred during transportation, contaminating trailer floors and bedding material. If not cleaned and sanitized between trips, trailers and bedding have the potential to infect other farms, the abattoir environment, or other animals with Salmonella. Floors and bedding material from pig trailers were sampled to determine the efficacy of the abattoir-developed washing and sanitizing regime on the level of Salmonella before and after a single haul. Escherichia coli levels were an indicator of high contamination. The study also determined the effect of ambient temperature (during four seasons) and of the distance the pigs traveled in the haulers (> 500 miles or < 500 miles) on bacterial levels. Salmonella was isolated from 80% of the bedding material tested. Of the 188 floor samples taken, 41.5% were positive for Salmonella before washing, and 2.7% were positive after washing and sanitizing. E. coli was isolated from all bedding material and floor samples before washing, but washing and sanitizing significantly decreased levels (P < 0.05) by 2 logs. There was no significant difference (P > 0.05) in the number of Salmonella- or E. coli-positive trailers attributable to distance traveled or season of the year. These results demonstrate that washing and sanitizing the trailers after each load significantly reduced levels of Salmonella and its possible spread by the contaminated trailer and bedding, which ultimately could promote improvement in food safety.