FAYETTEVILLE, Ark. — Researchers at the University of Arkansas have developed a faster method for detecting levels of certain salmonella types, or serovars, on poultry. The research lays the foundation for improved food safety monitoring in poultry products.

Today’s “selective enrichment” salmonella detection methods involve culturing samples taken from processed chicken and chicken products in a laboratory. After they have time to grow, the cultures are evaluated for the presence of salmonella organisms. This method can take up to five days, according to Steven Ricke, director of the UA Center for Food Safety. “As you get away from having to grow the organism, you can cut down on that time,” he said.

Another challenge for the selective enrichment method: It puts growth restrictions on the kinds of organisms that may grow in the cultures. While those cultures are favorable to the growth of salmonella, those cells still have to compete within the culture. “If you can avoid a selective (enrichment) step, it greatly speeds up the process,” said Ricke.

Avoiding selective enrichment also makes results more accurate. As some salmonella serovars compete with other organisms in the lab culture, the level of some serovars can actually decline. “You’d really like to know how many (salmonella) are present, as well as which serovar it is,” explained Ricke.

Some serovars are not pathogenic, and it takes a certain level of salmonella to make humans sick. The UA research team, led by Ricke and collaborator Si Hong Park, used molecular techniques to bypass the selective step. The multiplex polymerase chain reaction (PCR) technique used identified the presence of salmonella DNA in about 36 hours – less than half the time needed for current assays.

The multiplex PCR method also offers other benefits for food safety monitoring. It amplifies the DNA sequences of multiple salmonella serovars, meaning just one test could identify levels of numerous salmonella types. “Considerable time and costs can be saved with this method,” said Ricke. Further, the research team standardized its test so it could identify as few as 46 copies of salmonella chromosomes within a sample. “That equals 46 cells, which is a pretty low level, depending on the sample size.”

The next step for the UA researchers is to scale up the test so it can be used in a poultry processing plant. This will involve developing a test kit that can be used in plant diagnostics. Continuing to decrease the test time is also a goal, said Ricke, who added tests delivering results in less than a day would be ideal.

“We’re quite a ways from there, but this project is a big step,” he said.

Poultry products are regarded as a primary source of infection for foodborne salmonellosis, according to the Centers for Disease Control and Prevention. Poultry parts are more likely to be contaminated with salmonella than whole birds, according to the USDA, which released new salmonella testing protocol in January. The research was funded by a grant from the U.S. Poultry & Egg Harold E. Ford Foundation, or USPOULTRY Foundation.