A 6 x 6 drop plate method for simultaneous colony counting and MPN enumeration of Campylobacter jejuni, Listeria monocytogenes, and Escherichia coli.

A protocol was developed using 96-well plates and multichannel pipettes for serial dilutions, followed by drop plating on agar in a 6 x 6 format. This protocol permits simultaneous plating of six dilutions which greatly decreases the number of plates utilized thereby saving incubator space for organisms such as Campylobacter which require unique environmental conditions.