Enhancement of viable Campylobacter detection by chemotactic stimuli.

The effects of chemotactic stimuli on motility ability of viable Campylobacter to pass through a 0.45 microm pore size filter in viscous condition were investigated. Reference strains including C. jejuni ATCC 33291, C. coli MUMT 18407, C. lari ATCC 43675, and C. upsaliensis DMST 19055 were used. The initial numbers of artificially-inoculated viable cells per g of chicken meat were approximately 10 to 10(4). Constituents of mucin plus bile (1:1), varieties of amino acids, and sodium salts were added into a soft-agar-coated membrane filter and incubated at both 37 degrees C and 42 degrees C for 24h. The drop plate method was used to determine numbers of viable Campylobacter at 6, 12, 18, and 24h. After 6h, constituents of mucin plus bile at the concentrations of 1, 5, and 10% demonstrated significant increases in numbers of viable cells (p<0.05). The numbers of the organisms at 42 degrees C were higher than those at 37 degrees C. In contrast, no significant difference in cell numbers was observed by adding amino acids or sodium salts. In addition, the role of starvation on chemotactic responses was also studied. Starved cells showed lower chemotactic response than non-starved cells. This method permitted rapid detection of viable thermophilic Campylobacter.