How many patients do you need to screen for methicillin-resistant Staphylococcus aureus to find a positive? Results from a screening programme in a UK teaching hospital

Abstract number: O196

Jones G., Sutton J.K., Aplin S., Browning D.

Objectives: Screening for methicillin-resistant Staphylococcus aureus (MRSA) became mandatory in the UK for all elective and day case admissions from April 2009 and will be mandatory for all emergency admissions from April 2011. Data to assess the effectiveness of this strategy at an individual hospital level are lacking. We analyzed our screening programme data to determine the number needed to test (NNT) to detect a colonised patient across a range of clinical specialties, and develop a risk assessment strategy for MRSA screening.

Methods: MRSA screens of nose and groin were performed using chromogenic agar, with additional sites such as wounds and catheters included when present. In our hospital, MRSA screening data were resolved prospectively to individual patient level as opposed to a commonly utilized approximation using matched census (admission) data. Screening data were mapped to a patient administration system database containing relevant speciality codes. Mismatches where no screening results existed for individual patients were investigated weekly and included identification of patients in specific categories excluded from screening. Screening efficiency by specialty was fed back weekly to clinical teams to drive improved performance. Rates of MRSA positivity and NNT to detect a positive patient were determined for each specialty.

Results: For the 12 months from October 2008, the laboratory performed >160,000 MRSA swabs on 51,855 individuals costing 600,000 Euros. Screening efficiency for elective admissions improved from 60% to 99% (2228/2249) and for emergency admissions from 76% to 97% (2996/3077). Overall, 1.2% of hospital admissions were MRSA positive, with 1.6%, 0.7% and 0.6% being MRSA positive in emergency, elective and day case cases respectively. The highest MRSA positivity rates were seen in emergency cases in hepatology (4.3%), interventional radiology (3.7%) and vascular surgery (3.3%). 1.5% of elective vascular surgery patients were MRSA positive. The lowest MRSA positivity rate was in day case orthopaedics where 1,006 patients were screened without detecting a single positive patient. NNT to detect a positive ranged from 24 to >1,006 depending on clinical speciality and admission type.

Conclusions: Accurate data on results of MRSA screening can be used to assess both risk for individual patient admissions and the cost effectiveness of screening in specific patient groups, and to enhance the efficiency of the screening process.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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