Evaluation of potential sources and mechanisms of Salmonella contamination of poultry

Abstract

The purpose of the following studies was to investigate the manner in which various factors, common to Poultry production, influence the contamination of Poultry by Salmonella. The extent of broiler farm environmental contamination with Salmonella and the predictive value of such contamination for subsequent flock contamination was investigated. The distribution of various stereotypes associated with broiler farm environmental contamination with Salmonelia and the relationship to subsequent flock isolations was also evaluated. To further investigate possible mechanisms by which Salmonella contamination of live birds may result in the contamination of processed carcasses, an in vitro radioligand adherence assay was developed. Four independent complete drag-swab samplings of the house environment of a 3 1-farrn-broiler production complex resulted in mean isolation frequencies of Salmonella of 43.5% for vacant (awaiting the placement of the next flock) farms and 75.8% for occupied (currently housing chickens) farms. Throughout the four sampling periods, a total of 25 different serotypes were isolated with ftequent simultaneous isolations of multiple serotypes from individual farms. The development of a rapid and repeatable radioligand binding assay to assess Salmonella adherence or binding to broiler skin and muscle tissue was completed in five experiments of two replicate trials each. No significant differences in radiolabeled ('H) Salmonella enteritidis adherence to broiler skin tissue samples were observed with increasing incubation time from 30 minutes to 180 minutes. In two experiments, the individual application of 50 mM acetic acid or 10 % Avgard (V (tri-sodium phosphate) resulted in significant reductions in the ability of 'H-S. enteritidiv to adhere or bind to skin and muscle tissue following a one hour incubation. The results of the environmental sampling of a broiler production facility report a higher frequency of Salmonella isolation on multiple swabs in occupied poultry houses, possibly indicating a quantitatively greater presence of Salmonella in these houses. These results further indicate little predictability or consistency of Salmonella serotype isolation on individual farms over time. With regard to the development of the in vitro radioligand Salmonella adherence assay, this technique may provide a rapid screen for candidate treatments and compounds aimed at reducing Salmonella adherence to poultry carcasses within the processing plant.