Police have charged a man with a number of offences after he produced a knife and assaulted staff at a medical facility in South Brisbane overnight. It is understood that Mater Hospital security staff were notified of the man after he was refused service due to his behaviour about 7.40pm in the reception area. It is alleged that the 28-year-old man produced a knife, threatened security staff and threw a chair and coffee table in the direction of two staff.