Markham Stouffville Hospital declared an outbreak of the potentially fatal bacteria C. difficile recently, the first to hit the Toronto-area hospital in a number of years.

The outbreak, which was declared on Dec. 20, affected an inpatient unit and a surgery unit.

Hospital spokeswoman Lisa Joyce refused Friday to say how many patients were affected by the outbreak. She also stressed that the units were not closed due to the outbreak.

"We have never closed units or restricted admissions to those units," she said. "There was an outbreak in the units but they were not closed."

However, it is limiting visitors to two per patient.

Joyce said that there were no deaths related to the 10-day-old outbreak.

C. difficile causes diarrhea and other intestinal diseases. It is brought on when antibiotics taken by a person kill off both "bad" and "good" bacteria. When the good bacteria are killed, this can cause the C. difficile to grow and release toxins that can damage the bowel.

It usually afflicts patients whose immune systems are already compromised, which include the elderly and those already sick.

Joyce said the number of patients has not grown substantially since the outbreak was first detected.

The hospital was confident that it has the bacteria under control, and was working within the guidelines of health officials to staunch the spread.

"Our frontline staff right up to our vice-president are so involved with this and are so committed to getting this under control so that it doesn't transmit any further," Joyce said. "I am fully confident we are doing everything we can."

A handful of hospitals have reported outbreaks recently. Last week, a patient with C. difficile died at the Greater Niagara General Hospital.