Research Note: A Modified Most Probable Number Technique to Enumerate Total Aerobes, Enterobacteriaceae, and Salmonella on Poultry Carcasses After the Whole Carcass Rinse Procedure

A modified most probable number (MPN) technique utilizing a single 10-fold dilution series was tested to enumerate the microbiological population from the whole carcass rinse procedure for poultry. Diluent for the MPN series was a general nutrient broth. Resuscitation of damaged cells and pre-enrichment of low numbers of microorganisms was accomplished by the MPN media. The MPN dilution tubes positive for growth were used to calculate the total aerobic bacterial population. Subculturing with tetrathionate enrichment broth and subsequent plating to differential media were used to identify and enumerate Salmonella. Enterobacteriaceae were enumerated by subculture of the MPN positive tubes in brilliant green (BG) bile 2% broth supplemented with 1% dextrose that were then observed for gas production. The aerobic bacterial counts obtained by the modified MPN were similar, yet significantly higher than those obtained with the conventional plate count techniques (P < .05), and both were significantly higher than the three tube MPN counts.