Characterization of the contribution of water activity and moisture content to the population distribution of Salmonella spp. in commercial poultry houses

Because Salmonella spp. can be spread from the production environment to th e consumer, strategies are required to control Salmonella. One such interve ntion involves control of the distribution of the organism in poultry litte r. In this regard, we have attempted to determine whether Salmonella spp. a re uniformly distributed throughout the litter of commercial poultry houses , or if they are unevenly localized to "hot spots" associated with high sur face litter water activity (A(w)) and high total moisture levels. Of the 86 houses sampled, 48 (55.8%) were positive for Salmonella spp. usin g a combination of the drag swab and targeted litter culturing methods. Dat a are presented that show that elevated A(w) and percentage moisture conten t values representative of targeted litter samples or whole-house moisture status are not statistically predictive of Salmonella contamination, using either drag swab or targeted litter culture results as indicators of contam ination. This study suggests that favorable environmental conditions for th e growth of Salmonella are unequally dispersed in poultry houses. Because t here is not equivalent distribution of salmonella in the surface litter, th e drag swab technique is apparently necessary to adequately survey for Salm onella spp. contamination. The findings further suggest that the developmen t of a methodology to detect areas within houses that possess risk factors favorable for Salmonella growth must also include elevated A(w) and percent age moisture content levels. This capability may enable a grower to detect and intervene in these targeted areas with neutralizing procedures, agents, or other substances to provide significant reduction of Salmonella or othe r poultry-associated food-borne pathogens.