What percentage of the general population carries Methicillin-resistant Staphylococcus aureus (MRSA)?

MRSA Carriage Rates in the General Population

The prevalence of MRSA carriage in the general population is approximately 0.8-1.5% of people, while overall Staphylococcus aureus nasal colonization affects about 22-37% of the general population. 1, 2, 3, 4

General Population Carriage Rates

Staphylococcus aureus Colonization

• Approximately 22-37% of the general population carries Staphylococcus aureus nasally 1
• National Health and Nutrition Examination Survey (NHANES) 2001-2002 data showed:
  • 31.6% (approximately 86.9 million persons) of the non-institutionalized US population was colonized with S. aureus 2, 3
  • This represents nearly one-third of the US population carrying the organism 2

MRSA Colonization

• MRSA prevalence among S. aureus isolates was 2.58% 2
• Overall MRSA carriage in the general population:
  • 0.84% in the US (approximately 2.2 million persons) 2, 3
  • 1.5% in a UK community-based survey 4

Variation by Demographics and Risk Factors

Age-Related Differences

• Among individuals with S. aureus isolates, those aged 65 years or older had the highest MRSA prevalence (8.28%) 2
• People younger than 65 years were more likely to carry S. aureus in general, but older adults were more likely to carry MRSA specifically 3

Racial/Ethnic Differences

• Hispanics had the highest prevalence of colonization with S. aureus but were less likely to have MRSA when colonized 2
• Persons of black race and those of Mexican birth had lower risk for S. aureus colonization 3
• Hispanic persons had significantly less risk of MRSA colonization compared to white persons 3

Other Risk Factors for MRSA Carriage

• Women, persons with diabetes, and those who were in long-term care in the past year were more likely to have MRSA colonization 3
• Prior history of MRSA infection, recent hospitalization, antibiotic exposure, and comorbidities such as immunosuppression increase the risk 1

Regional Variations

• In the Asia-Pacific region, countries with the highest community-associated MRSA prevalence were India (16.5%-23.5%), Vietnam (7.9%), and Taiwan (3.5%-3.8%) 5
• The Netherlands maintains an impressively low prevalence of MRSA (approximately 0.03% of patients) through their "search and destroy" approach 6

High-Risk Subgroups

• Children aged ≤6 years: 0.5%-40.3% MRSA carriage rate 5
• Household members of MRSA carriers: 13.0%-26.4% carriage rate 5
• Healthcare workers: 6.1% MRSA colonization rate 1
• Emergency department patients: 7.8% MRSA colonization rate 1

Clinical Implications

Understanding MRSA carriage rates is crucial for:

• Guiding preoperative screening protocols, particularly for high-risk surgeries like cardiac and orthopedic procedures 6
• Implementing appropriate decolonization strategies for carriers before surgery 6
• Developing targeted infection control measures in healthcare settings 6

The relatively low prevalence of MRSA in the general population (0.8-1.5%) should not lead to complacency, as more than 2.2 million people in the US alone carry this resistant organism, making vigilance in infection control protocols essential 2.