All Wales surveillance of methicillin-resistant Staphylococcus aureus (MRSA): The first year's results.

Over the last five years, hospitals in Wales have experienced difficulties with increasing numbers of isolates of methicillin-resistant Staphylococcus aureus (MRSA). Continuous total population surveillance of MRSA was introd uced with the objectives of gaining an understanding of. the extent and var iation in time acid place of its occurrence, the burden of disease and poss ible risk factors associated with its isolation and resistance to other ant ibiotics. All first isolates of MRSA from both hospital and community setti ngs and all isolates of methicillin-sensitive Staphylococcus aureus (MSSA) associated with bacteraemia and cerebrospinal fluid (CSF) isolates detected in medical microbiology laboratories in Wales were collected via CoSurv, a set of interconnected database modules for communicable disease control. A data set was collected on each isolate and the patient associated with tha t isolate and compiled centrally at CDSC (Wales) for all-Wales analysis of the MRSA situation. Surveillance started in January 1996 and at the end of the first year, 2700 new isolates of MRSA had been reported from hospital a nd community settings, giving a rate of 92.43/100 000 population. The incid ence of MRSA from bacteraemias and CSF was 5.20/100 000 compared with 12.70 /100 000 for MSSA. MRSA from bacteraemia and CSF was significantly more com monly associated with male patients than MSSA. MRSA patients were significa ntly older. For all MRSA isolates, the highest reporting rate was in men ag ed 75+ (647.21/100 000). The highest incidence of invasive disease was also in men aged 75+ (45.69/100 000). Isolates from postsurgical patients were more likely to be involved in invasive disease (OR=2.59, P<0.001) than stra ins from other sources. The majority of isolates were resistant to at least two antibiotics in addition to methicillin, most frequently erythromycin a nd the fluoroquinolones. Very little resistance to fusidic acid, mupirocin or rifampicin was reported. Continuous total population surveillance has pr ovided a minimum incidence of MRSA in Wales and has allowed a simple and in telligible picture of the problem to be determined, which has been fed back to hospitals to assist decisions on control.