Dunedin Hospital is confident an antibiotic-resistant bacteria is contained.
One more sample has screened positive for vancomycin-resistant enterococcus, taking the total number of people affected to six.
In all the cases the bacteria is in, or on, a patient's body but they are not sick because they have not developed an infection.
"The majority of the large number of screening results have now come back and it appears that the infection has been contained thanks to the hard work of our staff," says Southern DHB chief medical officer, Nigel Millar.
All patients colonised with VRE have been isolated whilst in hospital, and measures have been taken to control the situation.
This is the first time VRE has been identified in a Southern DHB facility. It has been an increasing problem in other DHBs in New Zealand and across the world.
"VRE stems from the overuse of antibiotics and we need to reduce antibiotic resistance by monitoring the use of antibiotics, prescribe antibiotics correctly and aim to reduce overall use.
"We have all have a role to play in reducing substantially our use of antibiotics and that includes health professionals and patients," Dr Millar said.