A dirty kitchen appliance used to blend and puree food has been blamed as the source of a salmonella outbreak at the Burnside War Memorial Hospital in Adelaide's eastern suburbs.

Health Minister Jack Snelling today said the number of patients with gastroenteritis linked to the private hospital since July had increased to 16.

SA Health said a stab mixer had now been identified as a source of the contamination after testing ruled out imported fish earlier this month.

The development prompted Mr Snelling to issue a warning to kitchen staff, urging that appliances be properly dismantled, cleaned and sanitised.

SA Health's director of food safety and nutrition Fay Jenkins said hospital staff incorrectly believed the appliance was clean, but admitted she was "a bit shocked that it was so dirty".

"Due to the way it was constructed, the mixer was unable to be dismantled, which meant thorough cleaning and sanitising could not occur and harmful bacteria were able to survive within the appliance," she said.

"The stab mixer has since been removed from the Burnside War Memorial Hospital kitchen and further actions have been taken to prevent potential cross contamination."

SA Health has issued a warning to kitchen staff, urging that appliances be properly dismantled, cleaned and sanitised after this appliance caused a salmonella outbreak. ( SA Health )

Mr Snelling said he understands that the hospital now intends to only use mixers that can be dismantled for cleaning.

"In the particular case of this mixer, a technician actually had to be brought in to pull the mixer apart to enable it to be cleaned properly," he said.

"These mixers that otherwise appear perfectly clean, lurking inside them can be some very, very nasty germs.

"This is a very important time to give a warning out to all South Australians, but especially those in commercial kitchens, to make sure that their mixers are able to be properly cleaned, that there isn't food residue building up in parts of the mixer that can't be accessed."

Ms Jenkins said the Burnside hospital is, like public hospitals, subject to auditing but said that, in the case of private hospitals, that process is not carried out by the department.

"A mixture of the local councils provide that service," she said.

"This sort of thing should have been picked up and they were looking at whether it was being cleaned properly and it appeared to be, but it's not until we actually took it apart and looked at it and actually took some samples that we found it wasn't being cleaned properly."

Mr Snelling said details about the case would be passed on to Consumer Affairs to make a decision about identifying the brand of mixer responsible.

"It might not be just this brand, it could be a number of brands."

In a statement the hospital said a further 30 tests conducted throughout the kitchen returned negative results for salmonella.

The hospital apologised to patients that fell ill because of the dirty appliance.

"We continue to accept responsibility, keep patients informed and express our regret to those who became ill with gastroenteritis following exposure at the hospital," the statement read.

"The Burnside War Memorial Hospital's priority always is the provision of safe, contemporary care for every patient.