Methods for screening for methicillin-resistant Staphylococcus aureus carriage.

Area of Science:

• Clinical Microbiology
• Infectious Disease Control
• Hospital Epidemiology

Background:

• Hospital admission screening for methicillin-resistant Staphylococcus aureus (MRSA) carriage is a standard infection control measure.
• The effectiveness of MRSA control programs is presumed to improve with rapid screening result reporting and clear action plans for positive cases.

Purpose of the Study:

• To evaluate the effectiveness and cost-efficiency of different MRSA screening methods.
• To compare culture-based methods with polymerase chain reaction (PCR) based diagnostics for MRSA detection.

Main Methods:

• Direct inoculation of pooled swabs (nose, throat, perineal) onto MRSA-selective chromogenic agar.
• Confirmation of presumptive MRSA colonies using latex agglutination.
• Evaluation of selective enrichment broth methods.
• Assessment of PCR-based methods for same-day MRSA detection.

Main Results:

• MRSA-selective agar with latex agglutination provides results for >95% of true positives within 24 hours, sufficient for initial decisions.
• Antimicrobial susceptibilities are available the day after initial culture results.
• PCR methods offer same-day results but are more costly and may have higher false-positivity rates.
• The clinical cost-effectiveness of PCR, especially point-of-care tests, requires further investigation.

Conclusions:

• Culture-based methods, particularly chromogenic agar with latex agglutination, are effective and provide timely results for MRSA screening.
• While PCR offers speed, its higher cost and unproven cost-effectiveness limit its widespread adoption for MRSA screening.
• Further studies are needed to establish the clinical cost-effectiveness of rapid PCR and point-of-care MRSA tests.