What Is MRSA Colonization?


MRSA colonization is when bacteria reside on an individual, but there are no signs or evidence of infection. An individual colonized with MRSA bacteria is called a MRSA carrier. These individuals are unaware they are harboring MRSA. 

MRSA colonization places you at risk for a MRSA infection.

MRSA Infections can develop days to years after initial colonization. 

Why Is MRSA Colonization Important?

  • Colonized individuals are at risk to develop a MRSA infection, and have the potential to transfer MRSA bacteria to others.
  • MRSA colonization remains for years. In one study 20% of patients colonized with MRSA remained colonized after 4 years.1
  • MRSA Infections can develop days to years after initial colonization. It is not known if delayed infections stem from the initial colonization or from new exposures. 
  • MRSA colonization in our communities – is a risk factor for skin and other serious infections. 
  • MRSA colonization in the hospital setting – is a significant concern in the following areas:
    • Pre-surgical setting – colonization has the potential to increase post-surgical infections.
    • Intensive care units – critically ill patients are in a weakened state to fight infection.

1-2% of the U.S. population is colonized with MRSA bacteria.

How Common Is MRSA Colonization?

  • 1-2% of the U.S. population is colonized with MRSA bacteria.
  • However, in specific populations, 20% or more of the individuals are colonized with MRSA. Populations with a high colonization rate range in age from infants2 to the elderly in long-term care.3  

MRSA Colonization: Can You Work or Attend School?

MRSA colonization typically does not cause work or school limitations.  This is because:

  • MRSA colonization is not distributed evenly over one’s body.  
  • Easily washed areas tend to be void of bacteria, i.e. washed hands.  
  • Good hygiene will prevent the spread of MRSA. This includes regular hand washing, and keeping fingernails trimmed.


1 Duration of colonization with methicillin-resistant Staphylococcus aureus. Robicsek A, et al. Clin Infect Dis. 2009;48(7):910.
Relationship Between Maternal and Neonatal Staphylococcus aureus Colonization. Natalia Jimenez-Truque, et al. April 2012 online edition of Pediatrics.
3 Quantitative analysis and molecular fingerprinting of methicillin-resistant Staphylococcus aureus nasal colonization in different patient populations: a prospective, multicenter study. Mermel LA, et al. Infect Control Hosp Epidemiol. 2010 Jun;31(6):592-7.