Researchers Investigate Rate of Patients Missed by MRSA Screening Programs

Targeted screening of patients at high risk for methicillin-resistant Staphylococcus aureus (MRSA) carriage is an important component of MRSA control programs, which rely on prediction tools to identify those high-risk patients. Most previous risk studies reported a substantial rate of patients who are eligible for screening, but failed to be enrolled. The characteristics of these missed patients are seldom described. Pasricha, et al. (2013) aimed to determine the rate and characteristics of patients who were missed by a MRSA screening programme at our institution to see how the failure to include these patients might impact the accuracy of clinical prediction tools.

From March 2010 through June 2010 all patients admitted to 13 internal medicine wards at the University of Geneva Hospital (HUG) were prospectively screened for MRSA carriage. Of 1,968 patients admitted to the ward, 267 patients (13.6 percent) failed to undergo appropriate MRSA screening. Forty-one (2.4 percent) screened patients were MRSA carriers at admission. On multivariate regression, patients who were missed by screening were more likely to be aged<50 years (OR 2.4 [1.4-3.9]), transferred to internal medicine from another ward in the hospital (OR 2.8 [1.1-7.1]), and have a history of malignancy (OR 3.2[2.1-5.1]). There was no significant difference in the rate of previous MRSA carriage between screened and unscreened patients.

The researchers say their findings highlight the potential bias that missed patients may introduce into MRSA risk scores. They add that reporting on the proportions and characteristics of missed patients is essential for accurate interpretation of MRSA prediction tools. Their research was published in Antimicrobial Resistance and Infection Control. 

Reference: Pasricha J, Harbarth S, Koessler T, Camus V, Schrenzel J, Cohen G, Pittet D, Perrier A and Iten A. Methicillin-resistant Staphylococcus aureus risk profiling: who are we missing? Antimicrobial Resistance and Infection Control 2013, 2:17 doi:10.1186/2047-2994-2-17