This weekend, McDonald's restaurants in the U.S. removed tomatoes from many menu items, and numerous other chains in Canada have now done the same, including:

• Burger King
• Kelsey's
• Swiss Chalet
• Milestones

Many airlines have also removed tomatoes from their in-flight meals.

McDonald's restaurants in Canada stopped serving sliced tomatoes on the weekend after three varieties -- red plum, red roma and round red tomatoes -- were linked to a salmonella infection discovered in 16 U.S. states.

The restaurant chains say they have removed tomatoes as a precaution only, as no incidents of the outbreak have been found in Canada. However, Tim Hortons cites a supply issue, saying the American Food and Drug Administration's investigation into the outbreak has caused supply issues in the delivery chain.

Danya Proud, spokesperson for McDonald's in the U.S., said Monday that the company will continue putting grape tomatoes in salads since no illnesses have been linked to that variety.

On Saturday, the FDA alerted American consumers and restaurateurs of a nationwide outbreak of an uncommon type of Salmonella -- serotype Saintpaul -- linked to tomatoes, advising that their consumption should be limited.

Cherry tomatoes, tomatoes with the vine still attached and any grown at home are not included in the FDA warning. No Canadian tomatoes have been associated with the outbreak, according to a Canadian Food Inspection Agency's press release.

Since mid-April, there have been 145 reported cases of salmonellosis in the States caused by this particular strain. At least 23 related hospitalizations have been reported but no deaths have been linked to the outbreak.

Salmonella can cause serious and sometimes fatal infections, particularly in young children, elderly people and those who are sick. Symptoms include fever, diarrhea, nausea, vomiting and abdominal pain.

With files from The Canadian Press