Effect of biosecurity and management practices on the prevalence of Salmonella, Campylobacter, and Clostridium perfringens in a poultry production system
Type of DegreeMaster's Thesis
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Salmonella, Clostridium perfringens, and Campylobacter are responsible for 30% of all foodborne illness cases and 50% of foodborne illness hospitalizations in the United States. Many of these cases and outbreaks have been linked to poultry products as the source of contamination. Because of the significant impact these pathogens have on human health, they are direct targets for pathogen reduction programs at various points during poultry production. Pre-harvest control points are the most recent targets for pathogen control due to increasing costs, regulations and the presence of diseases such as Avian Influenza (AI) and Necrotic Enteritis (NE) caused by C. perfringens. Of particular interest are the specific biosecurity and management practices that influence the transmission of pathogens in the poultry production environment. This study aimed to determine which practices influenced the transmission of Salmonella, C. perfringens, and Campylobacter on commercial poultry farms. In addition, this study collected data on the presence of two novel C. perfringens genes (netB and tpeL) that produce toxins and are associated with the disease NE in poultry. A biosecurity and management survey was sent out to all of the growers for a single Integrator in Alabama. Responses were collected, analyzed and general recommendations for biosecurity and management program improvement were made to Integrator management. A year later, the survey was sent to the same growers to determine if there were any differences in practices. The reported farm characteristics for both surveys were very similar with only two instances of statistical significance. There was no statistical significance between the two surveys for any biosecurity or management practice. These results in conjunction with conversations with the growers indicated that the company did not make any changes to their biosecurity and management program as a result of our recommendations. In addition, compliance with many of the most common biosecurity practices was better than that found by previous studies (Dorea et al., 2010; Vieira et al., 2009; Tablante et al., 2002). After the first survey was sent to the growers and the responses analyzed, four farms from the same Integrator were selected based on the average characteristics indicated by the survey. These four farms were sampled three times at even intervals throughout one grow-out period. During each visit, drag swabs, cloacal swabs and litter samples were obtained from each house and then analyzed for the presence of Salmonella, Clostridium perfringens, and Campylobacter. The total anaerobic and aerobic bacteria counts were also obtained from the litter samples. After the second survey was sent to the growers, the same four farms were again sampled in the same manner as before to determine if any differences in the microbial community could be detected as a result of changes in biosecurity and management practices. Only one instance of statistical significance (p<0.05) was found for all the samples tested for the presence of Salmonella. Recovery of Campylobacter was poor for the first sampling due to the cultivation methods used. After the recovery methods were adjusted, this organism was recovered at much higher levels using cloacal swabs. Campylobacter was not recovered at any point during this study from the drag swab samples. Only two visits (cloacal swabs) were statistically significant (p<0.05) for this organism. Recovery of C. perfringens was statistically significant (p<0.05) for four of the six visits. The anaerobic and aerobic bacteria each had three visits that were significantly different (p<0.05). PCR results for the two novel C. perfringens genes were consistent with previous findings and contribute to the growing body of evidence that suggests that tpeL is not as important of a virulent factor as previously thought and that while netB is an important virulent factor it is inconsistently present in C. perfringens isolates. The results of this study were unable to directly identify which specific biosecurity and management practices influenced bacterial prevalence on the commercial poultry farm. Despite this fact, valuable information was collected regarding common on-farm biosecurity and management practices, their compliance, and the microbial populations taken from a poultry house environment.