Comparative effect of thymol or its glucose conjugate, thymol-β- d -glucopyranoside, on Campylobacter in avian gut contents.

Campylobacter jejuniis an important human food-borne pathogen that can contaminate meat and poultry during processing. Consequently, strategies are sought to reduce the carriage ofC. jejuniin food animals before they arrive at the abattoir. Thymol is a natural product that reduces survivability ofCampylobacter in vitro, but its rapid absorption from the proximal alimentary tract limits its bactericidal efficacyin vivo. Thymol-β-d-glucopyranoside is more resistant to absorption than free thymol, but its administration to chickens has not been reported. In the present studies, 1 mM thymol-β-d-glucopyranoside was shown to exhibit near equal anti-Campylobacteractivity as 1 mM thymol when incubated anaerobically in avian crop or cecal contentsin vitro, resulting in reductions of 1.10–2.32 log10colony forming units mL−1inC. jejuniconcentrations after 24 h incubation. In a follow-up live animal study, oral administration of thymol-β-d-glucopyranoside, but not free thymol, significantly lowered (>10-fold) recovery ofCampylobacterfrom the crop of market-aged broilers when compared to placebo-treated controls (n= 6 broilers/treatment). Neither thymol-β-d-glucopyranoside nor thymol affected recovery ofCampylobacterfrom cecal contents of the treated broilers. These results indicate that rapid absorption or passage of free thymol from the crop precluded its anti-Campylobacteractivity at this site and throughout the entire gastrointestinal tract. Conversely, lower recovery ofCampylobacterfrom the crop of birds treated with thymol-β-d-glucopyranoside indicates this conjugate was retained and able to be hydrolyzed to biologically active free thymol at this site as intended, yet was not sufficiently protected to allow passage of efficacious amounts of the intact glycoside to the lower gut. Nevertheless, these results warrant further research to see if higher doses or encapsulation of thymol-β-d-glucopyranoside or similar glycosides may yield an efficacious additive to reduce carriage ofCampylobacteras well as other pathogens throughout the avian gut. [ABSTRACT FROM PUBLISHER]