Prevalence and risk factors for meticillin-resistant Staphylococcus aureus in adult emergency admissions--a case for screening all patients?

In this study we describe the prevalence and frequency of risk factors for meticillin-resistant Staphylococcus aureus (MRSA) colonization in emergency admissions during a one-year MRSA screening programme. Overall, 7801/13 826 (56.4%) adult emergency admissions by 6469 patients were screened for MRSA. Of those screened, 670/7801 (8.6%) admissions by 433 patients (6.7%) were colonized with MRSA. Risk factors studied were previous hospital admission, previous MRSA colonization and residence in care homes. Patients with any risk factor (MRSA positive: 366/3952 (9.3%) vs MRSA negative: 67/2450 (2.7%), P<0.001), advanced age (mean ages for MRSA positive and negative patients were 74.4 and 56.2 years, respectively (P<0.001)), and increasing frequency of hospital admissions (P<0.001), patients from care homes (41/184, 22.2%) and previous MRSA colonization (232/1855, 12.5%) had a significantly higher MRSA colonization rate. The cost of the screening programme was nearly 24,500 pounds. It was noticed that there was a substantial reduction in hospital-acquired MRSA and MRSA bacteraemia during the study period. The study was not designed to establish whether this reduction was causally associated with the screening programme. We conclude that there is a high MRSA colonization rate among emergency admissions, especially those with risk factors. Using a selective risk factor based screening strategy more than 60% of the patients would have to be screened but still 3952/6469, 67 (15.5%) MRSA carriers would have been missed. Screening of all emergency admissions to detect MRSA colonization is preferable to selective screening, relatively inexpensive, and might reduce the MRSA colonization rate of hospital-acquired MRSA and MRSA bacteraemia among emergency admissions.