They also believe their inquiries will help determine if the two cases are linked in any way.
On June 5, a baby in the Special Care Baby Unit at the Women’s and Children’s Hospital returned a positive swab for Serratia marcescens.
The infant is reported to be in a stable condition.
That came after two babies at the Flinders Medical Centre were confirmed to have the infection earlier this week.
A number of other babies at Flinders have been found to have the bug on their skin but are not considered infected.
Deputy Chief Medical Officer Mike Cusack said until a connection between the cases was ruled out, authorities would act as if they were linked and take all necessary precautions.
“Clearly that’s a possibility and that’s one we’re actively investigating,” he said on Saturday.
“The likelihood is that is not the case. Though we have to treat it as it is until we’ve proven otherwise.”
Serratia can cause urinary and respiratory issues, and lead to pneumonia.
Dr Cusack said despite the rarity of infections, it was quite common for people to carry the bug.
“It’s a very common organism in the environment,” he said.
“So as we stand here there will be this bug and other on the environment and on our skins.”
“The key issue is in a hospital and in an intensive care unit you’ve got very vulnerable children and their immune systems have not yet fully developed.
“So when you’ve got bugs on the skins, there is a risk that those bugs can gain entry to the body and cause a serious infection.”
Dr Cusack said the parents of the infected babies were understandably worried.
“That’s why it’s our job to undertake this investigation as quickly as possible to get the answers the parents need,” he said.