Biphasic Microtiter Method for Campylobacter Recovery and Enumeration

We developed a biphasic method for recovery and enumeration of campylobacters. The biphasic system was composed of 96-well microtiter plates containing Campy–Line agar prepared 2¥ for all ingredients except for 1¥ agar (0.1 mL per well). Samples were prepared in either twofold or fivefold dilution series across separate 96-well plates and directly transferred (0.1 mL) to the agar-containing microtiter plates to create the biphasic system. Biphasic plates were incubated for up to 48 h at 42C either aerobically or microaerobically in a gas mixture of 5% O2, 10% CO2 and 85% N2. Campylobacter was recovered in the aerobically incubated biphasic plates; however, significantly greater Campylobacter recovery was obtained in the biphasic plates incubated microaerobically (P 0.05). Significantly higher numbers of injured campylobacters from chicken carcass rinse samples were recovered by the biphasic method compared with conventional direct plating techniques (P 0.05).