MRSA admission screening in a low prevalence setting - much ado about nothing?

Area of Science:

• Infectious Diseases
• Hospital Epidemiology
• Clinical Microbiology

Background:

• Rising rates of Methicillin-resistant Staphylococcus aureus (MRSA) necessitated updated screening and isolation protocols.
• A significant increase in newly diagnosed MRSA patients in 2007 prompted a review of existing surveillance strategies.

Purpose of the Study:

• To prospectively assess the effectiveness of new MRSA admission screening and pre-emptive isolation guidelines.
• To evaluate the yield of targeted MRSA screening in a low-prevalence hospital setting.

Main Methods:

• A one-year surveillance study (April 2008-March 2009) was conducted in a tertiary-care hospital and affiliated facilities in Eastern Switzerland.
• Patients were risk-stratified for MRSA screening and isolation based on epidemiological and personal risk factors.
• Admission screening involved nasal, throat, and axillary/inguinal swabs, supplemented by other samples as indicated.

Main Results:

• MRSA admission screening identified 3.7% of patients as positive (Number Needed to Screen: 27).
• Pre-emptive isolation identified 6.3% of patients as positive (Number Needed to Isolate: 16).
• Only 22.2% of newly diagnosed MRSA cases were detected through admission screening; the majority were identified via clinical samples during hospitalization. Patients with wounds constituted 80% of MRSA-positive individuals. Axillary/inguinal swabs did not improve screening sensitivity.

Conclusions:

• In low MRSA prevalence environments, risk-based admission screening has limited sensitivity for detecting new MRSA cases.
• The findings underscore the continued importance of adhering to standard precautions for effective MRSA transmission prevention.
• Targeted screening strategies may miss a significant proportion of MRSA infections, emphasizing the need for comprehensive infection control measures.