Methicillin resistant staphylococcus aureus, or MRSA, is a bacteria and a resistant form of staphylococcus aureus. MRSA can exist without affecting people's health. Information on the incidence of such asymptomatic carriage is not routinely reported. For the purpose of the surveillance, prevention and control of this infection, the Health Protection Surveillance Centre collects data on MRSA bacteraemia as part of the European antimicrobial resistance surveillance system, which collects data on the first episode of blood stream infection per patient per quarter and was designed to allow comparison of antimicrobial resistance data between countries and possibly between regions.
Since 1 January 2004, MRSA bacteraemia has been included in the list of notifiable diseases under the Infectious Diseases Regulations 1981, as amended. The reporting process is done on a quarterly basis from laboratories to the Health Protection Surveillance Centre via the European antimicrobial resistance surveillance system. The cases reported by the centre refer to hospitalised cases and are not representative of the general population. MRSA infections occur almost exclusively in hospital practice in Ireland, among hospital inpatients or patients who have frequent contact with hospitals. Community-acquired MRSA infections are generally caused by strains of MRSA bacteria which are different to strains associated with hospitals. The national MRSA reference laboratory carried out a preliminary study in 2005 to look for evidence of community-acquired strains of MRSA in Ireland. It identified five patients with such strains, four of whom appear to have acquired the infection outside Ireland. Current evidence suggests that MRSA is still confined to hospitals in Ireland.