Reduction of Salmonella on a Meat-based Pet Kibble Using Lactobacillus salivarius (L28)

Introduction: Pets carrying Salmonella in their feces may be a potential vehicle for contamination of the household environment, potentially leading to human illness.  Additionally, the pet food itself can be consumed inadvertently by children and pose a direct risk to the consumer.

Purpose: To determine the effect of Lactobacillus salivarius (L28) on the reduction of Salmonella in dry dog food kibble. 

Methods: A cocktail of Salmonella (Enteriditis, Newport, and Typhimurium) was inoculated into a chicken fat coating that was applied to each designated control and treatment sample to yield 10⁶ cfu/g on the product. Each sample was divided into two portions of a control sample and lactic acid bacteria (LAB) treated sample. Treated samples received L28 at concentrations to achieve 10⁶ cfu per 0.5 lb of kibble. After treatment, each portion was allowed to dry at room temperature for 4 hours. Pet kibble grab samples of 25 grams were collected and enumerated for Salmonella on XLD agar with a thin-layer overlay at 0, 4, 24, and 72 hours.

Results: At 0h, the Salmonella counts on the kibble were approximately 6.0 log CFU/g in control and L28 treated samples.  After four hours, both the control and treatments decreased in Salmonella, but the treated showed a 1.47 additional log reduction in comparison to the control. At 72h, the control counts were log 2.8 CFU/g. Furthermore, Salmonella was under the limit of detection after at 72h of treatment with L28. The experiment was replicated three times and there was a statistical difference between the Salmonella counts on the control and LAB treated pet kibble products. 

Significance: The results suggest that L28 may be used to inhibit Salmonella on pet food products, hence reducing the risk of salmonellosis in consumers.