Heartlands Hospital has reported 34 cases of salmonella in the June outbreak
Three people who caught salmonella died after an outbreak at a Birmingham hospital two months ago.
Officials from Public Health England are investigating an outbreak of the disease at Heartlands Hospital which saw dozens infected with the food poisoning bug.
There were 43 cases in the West Midlands, 34 of which were connected to an outbreak at the Bordesley Green hospital in June.
The hospital confirmed three people who had suffered from salmonella had died, but in two cases the disease was not the cause of death.
The third has been referred to the coroner's court and will be the subject to an inquest.
A Hospital spokeswoman said: "We can confirm that we have tested both food and water at the Heartlands site and have ruled these out as the root cause of the infection.
"We are working with the Health Protection Agency to investigate the other two cases, which includes the possibility of the infection being community acquired."
Eight wards were closed while the hospital took all steps to deal with the infection.
Public Health England is examining 156 cases across the country - including Hampshire, London and Cheshire - to discover the cause of the outbreak.
Dr Paul Cleary, a consultant epidemiologist leading the investigation, said they were making good progress and hoped to shortly have more conclusive evidence.
Professor Anthony Hilton, head of biological and biomedical science at Aston University, said if the cases across the country were related, the next step would be to identify common risk factors which link infected individuals.
"This might be consumption of a contaminated food or ingredient or even a common exposure at an event or activity.
"Compiling food and exposure histories of cases occurring over several months can be complex and time consuming, depending on the quality of the information available, and it may be some time before we know the true extent of the outbreak and the causative link, if any."
Public Health England's advice is to wash hands thoroughly before handling, preparing and eating food. Importantly, make sure all food is cooked properly before eating.