Cuckmere Ward is no longer taking in new patients and the movements of staff and patients have been restricted after the patients were diagnosed with clostridium difficile toxin-associated diarrhoea (CDATD), usually caused by the use of antibiotics which disturb the natural balance of bacteria in the bowel.
The infection control team is investigating these affected patients and the ward will be deep-cleaned with hypochlorite solution.
Tina Lloyd, lead infection control nurse at East Sussex Hospitals NHS Trust, said the trust had successfully reduced the numbers of patients with the bug, with a rate below the national average and the government-set limit.
Clostridium difficile is a bacteria present in the intestine of around three per cent of healthy adults.
If this bacteria remains within the gut it will not cause any harm.
CDTAD causes toxins in the gut which produce symptoms such as watery diarrhoea, abdominal pain and fever.
It most commonly affects elderly patients with other underlying conditions and a full recovery is usual.