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

Campylobacter jejuni is an important human food-borne pathogen that can contaminate meat and poultry during processing. Consequently, strategies are sought to reduce the carriage of C. jejuni in food animals before they arrive at the abattoir. Thymol is a natural product that reduces survivability of Campylobacter in vitro, but its rapid absorption from the proximal alimentary tract limits its bactericidal efficacy in vivo. Thymol-ß-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-ß-D-glucopyranoside was shown to exhibit near equal anti-Campylobacter activity as 1 mM thymol when incubated anaerobically in avian crop or cecal contents in vitro, resulting in reductions of 1.10-2.32 log10 colony forming units mL(-1) in C. jejuni concentrations after 24 h incubation. In a follow-up live animal study, oral administration of thymol-ß-D-glucopyranoside, but not free thymol, significantly lowered (>10-fold) recovery of Campylobacter from the crop of market-aged broilers when compared to placebo-treated controls (n = 6 broilers/treatment). Neither thymol-ß-D-glucopyranoside nor thymol affected recovery of Campylobacter from cecal contents of the treated broilers. These results indicate that rapid absorption or passage of free thymol from the crop precluded its anti-Campylobacter activity at this site and throughout the entire gastrointestinal tract. Conversely, lower recovery of Campylobacter from the crop of birds treated with thymol-ß-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-ß-D-glucopyranoside or similar glycosides may yield an efficacious additive to reduce carriage of Campylobacter as well as other pathogens throughout the avian gut.

Effects of repeated-low level sodium chlorate administration on ruminal and fecal coliforms in sheep.

Abstract The objective of this study was to evaluate the efficacy of oral sodium chlorate administration on reducing total coliform populations in ewes. A 30% sodium chlorate product or a sodium chloride placebo was administered to twelve lactating Dorper X Blackbelly or Pelibuey crossbred ewes averaging 65 kg body weight. The ewes were adapted to diet and management. Ewes were randomly assigned (4/treatment) to one of three treatments which were administered twice daily by oral gavage for five consecutive days: a control (TC) consisting of 3 g sodium chloride/animal/d, a T3 treatment consisting of 1.8 g of sodium chlorate/animal/d, and a T9 treatment consisting of 5.4 g sodium chlorate/animal/d; the latter was intended to approximate a lowest known effective dose. Ruminal samples collected by stomach tube and freshly voided fecal samples were collected daily beginning 3 days before treatment initiation and for 6 days thereafter. Contents were cultured quantitatively to enumerate total coliforms. There were no significant differences in total coliform numbers (log10 cfu/g) in the feces between treatments (P = 0.832). There were differences (P < 0.02) in ruminal coliform counts (log10 cfu/mL) between treatments (4.1, 4.3 and 5.0 log10/mL contents in TC, T3 and T9 Treatments, respectively) which tended to increase from the beginning of treatment until the 5th day of treatment (P < 0.05). Overall, we did not obtain the expected results with oral administration of sodium chloride at the applied doses. By comparing the trends in coliform populations in the rumen contents in all treatments, there was an increase over the days. The opposite trend occurred in the feces, due mainly to differences among rumen contents and feces in ewes administered the T9 treatment (P = 0.06). These results suggest that the low chlorate doses used here were suboptimal for the control of coliforms in the gastrointestinal tract of ewes.

Comparison of anti-Campylobacter activity of free thymol and thymol-ß-D-glucopyranoside in absence or presence of ß-glycoside-hydrolysing gut bacteria.

Thymol is a natural product that exhibits antimicrobial activity in vitro but in vivo results indicate that absorption within the proximal alimentary tract precludes its delivery to the distal gut. Presently, the anti-Campylobacter activity of thymol was compared against that of thymol-ß-D-glucopyranoside, the latter being resistant to absorption. When treated with 1 mM thymol, Campylobacter coli and jejuni were reduced during pure or co-culture with a ß-glycoside-hydrolysing Parabacteroides distasonis. Thymol-ß-D-glucopyranoside treatment (1 mM) did not reduce C. coli and jejuni during pure culture but did during co-culture with P. distasonis or during mixed culture with porcine or bovine faecal microbes possessing ß-glycoside-hydrolysing activity. Fermentation acid production was reduced by thymol-ß-D-glucopyranoside treatment, indicating that fermentation was inhibited, which may limit its application to just before harvest. Results suggest that thymol-ß-D-glucopyranoside or similar ß-glycosides may be able to escape absorption within the proximal gut and become activated by bacterial ß-glycosidases in the distal gut.

Foodborne Campylobacter: infections, metabolism, pathogenesis and reservoirs.

Campylobacter species are a leading cause of bacterial-derived foodborne illnesses worldwide. The emergence of this bacterial group as a significant causative agent of human disease and their propensity to carry antibiotic resistance elements that allows them to resist antibacterial therapy make them a serious public health threat. Campylobacter jejuni and Campylobacter coli are considered to be the most important enteropathogens of this genus and their ability to colonize and survive in a wide variety of animal species and habitats make them extremely difficult to control. This article reviews the historical and emerging importance of this bacterial group and addresses aspects of the human infections they cause, their metabolism and pathogenesis, and their natural reservoirs in order to address the need for appropriate food safety regulations and interventions.

Ex vivo absorption of thymol and thymol-ß-D-glucopyranoside in piglet everted jejunal segments.

Food-producing animals are reservoirs of Campylobacter, a leading bacterial cause of human foodborne illness. The natural product thymol can reduce the survivability of Campylobacter, but its rapid absorption in the proximal gastrointestinal tract may preclude its use as a feed additive to reduce intestinal colonization of these pathogens. This work examined the ex vivo absorption of thymol and thymol-ß-d-glucopyranoside in everted porcine jejunal segments, as the latter was hypothesized to be more resistant to absorption. A modified gas chromatography and extraction method was developed to determine 1.0-500 mg/L thymol. From 1 and 3 mM solutions, 0.293 ± 0.04 and 0.898 ± 0.212 mM thymol, respectively, p = 0.0347, were absorbed, and 0.125 ± 0.041 and 0.317 ± 0.143 mM thymol-ß-d-glucopyranoside, respectively, p = 0.0892, were absorbed. Results indicate that thymol-ß-d-glucopyranoside was absorbed 2.3 to 2.8 times less effectively than thymol, thus providing evidence that thymol-ß-d-glucopyranoside may potentially be used as a feed additive to transport thymol to the piglet lower gut.