A novel miniaturized most probable number method for the enumeration of Campylobacter spp. from poultry-associated matrices

Abstract

A novel miniaturized most probable number (mMPN) method was developed for the enumeration of thermophilic Campylobacter spp. using a modification of blood-free Bolton broth (supplemented with 25mg/l of sulfamethoxazole) and CampyFood ID agar. The mMPN was evaluated by comparison with direct plating (modified ISO/TS, 10272-2:2006) for the analysis of samples (n=149) representing various poultry matrices (carcases, broiler ceca and feces, scald tank water and feed). A sensitivity of 95%, specificity of 90% and Cohen KAPPA agreement of 0.84 was determined for the mMPN method compared to direct plating. Quantitative comparison found 83% of enumerations to be less than ±1log10 different (Student's t-test P<0.001). Financial analysis showed that the mMPN required 51% less media and 60% less labor than the direct plating protocol. The mMPN provides a method that can be used for complete through-chain analysis that has a single enrichment step and multiple dilutions to extinction for a variety of samples (containing low, medium and high populations).