National supermarket chain Kroger (NYSE: KR) is recalling certain spinach shipments from stores in 15 different states, as worries abound that some packages of the leafy vegetable may be contaminated with listeria bacteria, the company said in a press release. Kroger has already removed all suspect units from its shelves and is requesting customers who’ve already purchased the product to return it for a refund or replacement.

Listeria most severely affects pregnant women, babies, the elderly, and those with weak immune systems, and it can be deadly if ingested and left untreated.

The recall includes 10-ounce packages of Kroger Fresh Selections Tender Spinach, UPC code 0001111091649, with a “best if used by” date of Sept. 16, the company said.

Stores in Alabama, Georgia, Illinois, Indiana, Kansas, Kentucky, Michigan, Missouri, Nebraska, North Carolina, Ohio, South Carolina, Tennessee, Virginia, and West Virginia were all involved in recalls, according to the company.