Four patients at Wakari Hospital in Dunedin have screened positive for an antibiotic resistant bacteria.
Vancomycin-resistant enterococcus, also known as VRE, can occasionally cause infections in the urinary tract, blood stream and wounds.
Southern District Health Board said four patients tested positive for VRE, but were not sick and had not developed an infection.
However, it was still taking the positive results very seriously, it said.
It was screening patients who had come into close contact or shared a room with the four patients at the hospital.