EPIDEMIOLOGY OF SALMONELLA CONTAMINATION OF POULTRY MEAT PRODUCTS: KNOWLEDGE GAPS IN THE FARM TO STORE PRODUCTS

Abstract

The ultimate goal of controlling foodborne hazards is to reduce the risk of disease to consumers, and the economic burden related to foodborne illness. A literature review identified four areas of insufficient data on the epidemiology of Salmonella. A cross-sectional study was used to estimate prevalence of enteric bacterial contamination of plant-based animal feed and milk replacer from Maryland and Northern Virginia. All samples were negative for Campylobacter; 0.6% were positive for Salmonella; 5.7 % for E.coli; and 50.6% for Enterococcus. Samples purchased in summer of 2002 were 38 times more likely to be contaminated with Enterococcus than samples purchased in winter of 2002 (p-value<0.001). Enterococcus positive samples were 8 times more likely to be E.coli positive than Enterococcus negative samples. Another cross-sectional study was used to assess the association between the pattern of airflow and the distribution of fecal coliforms and Salmonella in commercial chicken litter. At moderate relative humidity (about 50%), there was a significant association between regions of reduced airflow and increased coliform and Salmonella contamination within a poultry house. An analysis of a PCR technique to validate sensitivity and specificity relative to culture techniques for detecting Salmonella contamination in retail poultry meat was conducted. When only BPW pre-enrichment was used, the PCR test had a sensitivity of 85%. This increased to 89 - 100% when BPW pre-enrichment was followed by selective enrichment with RV or TT-H broth, respectively when conventional culture is the gold standard. A minimum of 12 hours pre-enrichment and 100 cfu was necessary to achieve 100% sensitivity with PCR.

Random poultry meat samples from 10 retail grocery outlets in Maryland were collected in the final cross-sectional study. Overall Salmonella prevalence in poultry meat products was 23% (C.I 15.16 - 30.86). Integrator brand ground chicken meat had an increased Salmonella prevalence compared to non-ground meat products; however this difference was not significant (p=0.0533). Store brand non-ground chicken meat products were 18 times more likely to be contaminated with Salmonella than integrator brands (C.I. 5.41-61.26).