Spatial and temporal analysis of microbial populations in production broiler house litter in the southeastern United States

Abstract

SUMMARY The main objectives of this study were to discern intrahouse spatial and temporal effects on foodborne and nuisance pathogen bacterial levels in actively used commercial broiler litter. The purpose of the study was to provide critical information regarding microbial hot spots, which may be targeted for site-specific litter treatments. A single broiler-concentrated animal feeding operation was monitored throughout 3 consecutive flocks. Salmonella enterica, Listeria monocytogenes, Staphylococcus spp., Enterococcus spp., Clostridium perfringens, and Campylobacter spp. were monitored at specific locations. Additionally, antibiotic resistance characteristics were quantified from bacterial isolates. Clostridium perfringens, Staphylococcus spp., and Enterococcus spp. were consistently present at levels of 7 log10, 12 log10, and 8 log10 cfu/ kg of litter, respectively; whereas S. enterica, Campylobacter spp., and L. monocytogenes were not present or present at low levels compared with other bacteria investigated. Temporally, S. enterica was found early in the flock, whereas C. perfringens, Staphylococcus spp., and Enterococcus spp. levels were greater later in the flock. The effect of flock cycle was noted for S. enterica and L. monocytogenes, which were found at greater frequency with the first flock (summer). Salmonella enterica was more commonly associated with the end walls, but overall it appeared that pathogen levels were difficult to predict.