Active surveillance for MRSA: The debate goes on

There are two new studies in the Journal of Hospital Infection, both from Europe, that add fuel to the MRSA active surveillance debate. The first examines national and local data in France prior to a 2009 recommendation from the French Society of Hospital Hygiene that MRSA screening be done in all ICUs for all patients with previous hospitalization, invasive devices, or previous antibiotic therapy. The authors point out that in a national point prevalence survey done in 2006, MRSA accounted for 6% of HAIs in ICUs, while Pseudomonas aeruginosa accounted for 15%. At their university hospital, the authors then analyzed one year of surveillance data from adult ICUs where active surveillance for MRSA and P. aeruginosa is performed on admission and then weekly. Colonization rates were 19% for P. aeruginosa vs. 4% for MRSA. P. aeruginosa accounted for 8% of infections, while MRSA accounted for 0.5%. Further analysis revealed that 50% of the patients who acquired P. aeruginosa after admission were the result of cross-transmission. Even if all MRSA was acquired via cross-transmission, Pseudomonas was 3 fold more likely to be transmitted than MRSA.

The second study is from an academic medical center in Ireland with an occupancy rate of 105% (i.e., 5% of admitted patients are boarders in the Emergency Department awaiting ward beds). The authors sought to determine whether patients identified as previously colonized or infected with MRSA wait longer for a hospital bed once the decision to admit from the ED has been made. Patients previously identified as colonized or infected are flagged in the hospital information system as is done in many hospitals. Patients were who flagged waited 2.5 hours longer for a hospital bed than those who were not. Thus, crowding in Emergency Departments is exacerbated by a MRSA active surveillance program.

Although much of the debate on MRSA active surveillance focuses on whether the intervention is effective in reducing transmission of MRSA in the inpatient setting, that is only one of the important issues. Other important questions are whether the intensity of resources required by active detection and isolation (ADI) are merited to control this organism when other important pathogens are more common, and the adverse unintended consequences of ADI, as pointed out by these studies.