The products are packed under the Frankly Fresh label in a variety of sizes with the affected code dates between March 19 and April 23, 2011. They were sold in California and Nevada stores.
The company says the bacterium was discovered during a routine sampling program by the FDA and Frankly Fresh.
Shoppers are urged to return the salads to stores for a full refund.
Listeria monocytogenes can cause serious and sometimes fatal infections in people with weakened immune systems.
So far, no illnesses have been reported.
The Associated Press contributed to this report.