The Salt Lake County Health Department said tests pointed to bacteria commonly found on skin that can be introduced to food when prepared with bare hands and not heated or cooled properly.
Nicholas Rupp, a spokesman for the health department, had no details about what was served to those who fell ill Sunday night or how it was prepared.
The bacteria are different from the more dangerous, drug-resistant staph bacteria found in hospitals.
Emergency crews were called to the shelter Sunday night after receiving reports of multiple people vomiting at the Road Home shelter. More than 50 were hospitalized but were all released by Monday.
The shelter did not serve any meals over the weekend, but many who stay there overnight eat at the same nearby kitchens and dining halls, including the St. Vincent de Paul Dining Hall.
Rupp said the health department is not taking any disciplinary action against the dining hall but it may step up its surprise inspections from the two visits a year the kitchen receives now to ensure proper protocols are being followed.
The dining hall has co-operated with the investigation and the suspected food poisoning appears to have been an isolated incident, the department said.
A message seeking comment from the St. Vincent de Paul Dining Hall was not returned Friday.
Health department inspectors visited the dining hall Monday morning and reported only one violation — that water in a sink used for hand washing did not reach 100 degrees Fahrenheit within 30 seconds.