CategoryPre-Harvest Pork Safety
Date Full Report Received08/18/2006
Date Abstract Report Received07/21/2008
InvestigationInstitution: Pennsylvania State University
Primary Investigator: Brenda Love
Co-Investigators: Marcos Rostagno
Funded ByNational Pork Board
Salmonella enterica is a bacterium that causes disease in many animals, including swine and human beings. This organism can be transmitted from swine to human beings through direct contact, or through indirect contact such as by eating pork products that have been contaminated with the organism (i.e., foodborne infections). Many European countries have implemented surveillance methods to detect pigs that are shedding Salmonella species as they go to slaughter, and these standards may eventually be adopted by the United States. In addition, diagnostic methods to detect Salmonella species are used to determine cause of illness in sick pigs. The traditional way to detect Salmonella species is to perform bacterial culture in a laboratory. This method, while traditional, widely used and somewhat standardized, can consist of many variations. If the sample probably contains very few bacteria, there can be a pre-enrichment step, where all organisms are allowed to grow to high numbers, followed by a selective enrichment step where the Salmonella are allowed to grow but other types of bacteria are inhibited. Finally, the samples are put onto a solid medium that contains biochemicals which help to identify Salmonella. This is especially useful when the sample is fecal material or intestinal tract, which contains many different types of bacteria.
It has been shown that variations in the steps used, or the type of media used for each of these steps in the culture procedure can greatly affect the amount and types of Salmonella recovered. It has also been shown that the same protocol, used in different laboratories, can result in differences in recovery of Salmonella. This project was conducted in order to evaluate five different culture protocols, used in one laboratory, on samples collected from pigs of known infection status (positive or negative). This research project generated information that can then be used to compare additional culture methods, besides of demonstrating how different culture methods perform for the recovery of Salmonella from naturally contaminated swine fecal samples.
Contact information: Dr. Brenda C. Love, 814-863-1984, Pennsylvania State University Animal Diagnostic Laboratory.