Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 24, 1998
Publication Date: N/A
Interpretive Summary: Listeria monocytogenes is a bacterium that is gaining in importance as the cause of a severe type of food poisoning in humans. Unlike many bacteria, Listeria has the additional trait of being able to grow at refrigeration temperatures. The increasing popularity of poultry among consumers increases the potential health risks from the eating of undercooked and refrigerated poultry products contaminated by Listeria. In the present study, chicks were treated with a commercial product called PREEMPT (formally called CF3), that had previously been shown to protect chicks against Salmonella bacteria, to determine the protective effects of PREEMPT against Listeria infections in chicks. Listeria was not detected in chicks given PREEMPT, while all chicks not given PREEMPT were infected. The conclusion is that PREEMPT protects chicks from infections by Listeria as well as Salmonella. The results of this study are of interest to researchers, growers, and producers of poultry products. Treatment of chicks with PREEMPT sould result in a decreased potential for food poisoning in consumers of poultry products.
Day-of-hatch Leghorn chicks were treated by oral gavage with PREEMPT (formally called CF3), a continuous-flow competitive exclusion culture containing broiler cecal bacteria, followed by an oral challenge with Listeria monocytogenes to determine the effects of PREEMPT on cecal colonization by L. monocytogenes. Increased concentrations of cecal propionic acid in chicks at 3 days of age were indicative of the establishment of the PREEMPT bacteria in the ceca of treated chicks. The average cecal concentration of propionic acid in control chicks in 4 trials was 3.53 +/- 1.4 umol/g of cecal contents, while cecal propionic acid levels in PREEMPT-treated chicks were significantly higher at 26.37 +/- 4.2 umol/g of cecal contents (P<0.001). Ceca from control chicks at 7 days after the oral challenge with L. monocytogenes contained an average (from 4 trials) of log 3.44 +/- 1.4 CFU/g of cecal content, while ceca from chicks given the prophylactic treatment with PREEMPT contained no detectable Listeria CFU. Enrichment of ceca for L. monocytogenes in two trials resulted in 100% of ceca from control chicks testing culture- positive for L. monocytogenes, while none of the ceca from PREEMPT-treated chicks were culture-positive for L. monocytogenes. The results indicated that prophylactic treatment of newly hatched chicks with PREEMPT significantly reduced cecal colonization by L. monocytogenes.