At least 20 people have been hospitalised owing to salmonella poisoning in Durban, KwaZulu-Natal, eNCA reported on Saturday.
Lancet Laboratories reportedly alerted doctors in the region about cases in both children and adults.
Food that has been affected include orange juice, eggs, fresh vegetables, frozen dinners, dairy products and peanut butter, based on tests by the laboratory.
Lancet says non-typhoidal salmonella species are the leading cause of bacterial food-borne illnesses.
Salmonella infection (salmonellosis) is a common bacterial disease that affects the intestinal tract. Salmonella bacteria typically live in animal and human intestines and are shed through faeces. Humans become infected most frequently through contaminated water or food, according to Mayo Clinic.
Symptoms usually include vomiting, stomach cramps and diarrhoea.
According to The Mercury, the outbreak started at the Old Town Italy restaurant in Umhlanga.
The restaurant's famous Hollandaise sauce - made from raw egg - is reportedly the source of the outbreak.
But according to Times LIVE, other instances of salmonellosis have been reported in the area.
Four children attending a Cowies Hill creche were reportedly confirmed by doctors to have salmonellosis.
In addition, seven people who attended a private lunch spent almost a week at Hillcrest Private Hospital after eating a dessert made with egg.
A restaurant in Florida Road was reportedly closed for two days after its patrons reported falling ill.
Many pharmacies in the greater Durban area have reported a sudden spike in the demand for diarrhoea medication, Times Live reported.
Lancet Laboratories urged people to practice proper hygiene and food safety.
"Food needs to be kept below 4C.
"People have also been urged to wash their hands and fresh foods before consuming.
"The public is also advised to properly cook food until it's well done," the laboratory said.