DIY Staph Testing

Sherod says The Schwan Food Company chose the 3M plates because they are accurate, easy to use, and require much less space than conventional plates. She adds that they also eliminate the time-consuming and labor-intensive media preparation required with traditional pour plates. “Testing with Petrifilm plates also gives us critical data we need to maintain our HACCP programs.”

The results of testing with Petrifilm plates determine the next steps taken, Sherod says. “We have internal specifications that govern our procedures. If Staph aureus organisms are present at certain levels in a particular ingredient, work in process, or finished product, we do secondary testing to determine whether enterotoxin is present.”

Schwan uses the Staph enterotoxin 2 or SET 2 method for secondary testing. At this stage, some companies may seek support from an outside laboratory to provide secondary testing or confirm their in-house results.

Making Necessary Corrections

A predetermined corrective action plan is another important aspect of an effective in-house testing program. Sherod recommends having a written plan ready before beginning the testing. If S. aureus is detected at unacceptable levels, then appropriate action can be taken.

“If our in-house testing indicates conditions are out of specification, we do a root cause analysis to find the ingredient, work in process, or finished product of concern. If the problem were in an ingredient, we would go back to the supplier to address the situation with them. If the problem were internal, we would revisit our good manufacturing processes with personnel who were working in the area where the problem occurred or take other appropriate corrective actions based on the root cause investigation,” Sherod says.

By following these steps, testing for S. aureus and managing the results can be done easily in house. Using proven equipment and count plates can facilitate the process by providing valuable time and labor savings.

Huemoeller is a market development supervisor at 3M; reach her at [email protected].

References

1. Downes FP, Ito K, eds. Compendium of Methods for the Microbiological Examination of Foods. 4th ed. Washington, D.C.: American Public Health Association; 2001.
2. Jay JM. Modern Food Microbiology. 6th ed. Gaithersburg, Md: Aspen Publishers; 2000.