Staphylococcus aureus



Methicillin-resistant Staphylococcus aureus (MRSA) is a type of Staphylococcus (staph) bacteria that is resistant to certain antibiotics called beta-lactams. These antibiotics include methicillin and other more common antibiotics such as oxacillin, penicillin, and amoxicillin. In the community, most MRSA infections are skin infections and may appear as red boils or pimples. More severe or potentially life-threatening MRSA infections occur most frequently among patients in healthcare settings and may initially present as symptoms such as fever and pain at the site of infection. While 25% to 30% of people are colonized in the nose with staph, less than 2% are colonized with MRSA. (citation)


Like MRSA, Vancomycin-intermediate Staphylococcus aureus (VISA) and Vancomycin-resistant Staphylococcus aureus (VRSA) are types of staph bacteria that are resistant (or have intermediate resistance) to certain antibiotics. Because of their resistance to antibiotics, VISA/VRSA infections can be more difficult to treat.  VISA/VRSA infections may affect the skin or may get into the bloodstream, causing a more serious type of infection.
Enterococci are a type of bacteria found naturally in the environment, as well as in the human intestines and the female genital tract. When these bacteria develop resistance to vancomycin, they become Vancomycin-resistant Enterococci (VRE). Most VRE infections occur in people who are hospitalized.

Factors that increase a patient’s risk of developing an infection caused by a MDRO may vary depending on the type of organism.  In general, risk factors include underlying health conditions, a weakened immune system, prolonged hospitalization, exposure to an invasive device such as a ventilator or catheter, recent surgery, and frequent antibiotic use.

MDROs are transmitted via direct contact with an infected person or indirect contact with contaminated objects/surfaces in the environment of an infected person. It is important that both the patient and the healthcare providers take the appropriate steps to help prevent an infection caused by a MDRO.

Infection Prevention

Because colonization (presence of an organism in/on the body without showing any symptoms) with a MDRO generally precedes infection (presence of an organism in/on the body causing tissue invasion or damage and actively causing symptoms), interventions primarily target two broad areas:

  • Preventing transmission from colonized persons to uncolonized persons
  • Preventing infection in colonized persons, which includes:
    • Strategies aimed at preventing device-associated and procedure-associated infections (e.g., central line-associated bloodstream infections, surgical site infections).  These strategies are general, so they apply to patients with or without a MDRO.
    • Decolonization strategies

To prevent the transmission of MRSA, doctors, nurses, and other healthcare providers can do the following things:

  • Clean their hands with soap and water or an alcohol-based hand rub before and after touching the patient or the patient’s environment.
  • Implement contact precautions, including the use of gown and gloves for patient care and use of dedicated non-essential items such as blood pressure cuffs and stethoscopes.
  • Identify previously colonized or infected patients.
  • Ensure that the facility has a mechanism for rapidly communicating positive laboratory results from the laboratory to clinical areas.
  • Provide ongoing education to improve adherence to hand hygiene, improve adherence to contact precautions, and to better understand the problem.
  • Facilities may also implement additional strategies including active surveillance testing, decolonization programs, or chlorhexidine bathing.


Reporting Requirements

In January 2013, the Centers for Medicare and Medicaid Services (CMS) began requiring acute care hospitals participating in their Hospital Inpatient Quality Reporting Program to report MRSA bacteremia facility-wide using the National Healthcare Safety Network (NHSN). These data are publicly available on Hospital Compare.

In September 2015, the VDH reporting regulations were updated to align state reporting requirements with the CMS Hospital Inpatient Quality Reporting Program. Under the new regulations, hospitals are reporting MRSA bacteremia LabID event data to VDH through the NHSN. For more information on these data and the state regulation mandating their reporting, please see the VDH Reporting Regulations page.

Other CMS quality reporting programs require MRSA bacteremia LabID event reporting from long-term acute care hospitals (January 2015 to present) and inpatient rehabilitation facilities (January 2015 to present).

Impact in the United States

Estimated burden in healthcare facilities in the United States:


  • An estimated 9,700 hospital-onset MRSA bloodstream infections occur annually in United States hospitals. (citation)
  • More than 80,000 invasive MRSA infections occurred in the United States in 2011. (citation)
    • Of those, nearly 18% were hospital-onset infections (cultured more than 3 days after hospital admission).
    • Invasive MRSA infections are reportable diseases in Virginia.
  • According to the latest CDC National and State HAI Progress Report, in 2014, acute care hospitals experienced a 13% reduction in hospital-onset MRSA infections compared to 2011.
    • Virginia hospitals have experienced a 9% decline in hospital-onset MRSA infections between 2011 and 2013.
  • Of the HAIs reported to the National Healthcare Safety Network from 2009-2010: (citation)
    • Nearly 20% of pathogens reported from all HAIs were the following multidrug-resistant organisms: MRSA (8.5%); vancomycin-resistant Enterococcus (3%); extended-spectrum cephalosporin–resistant K. pneumoniae and K. oxytoca(2%), E. coli (2%), and Enterobacter spp. (2%); and carbapenem-resistant P. aeruginosa (2%), K. pneumoniae/oxytoca (<1%), E. coli (<1%), andEnterobacter spp. (<1%).
    • 44-59% of healthcare-associated S. aureus infections were caused by MRSA.
    • 62-83% of healthcare-associated Enterobacter faecium infections were resistant to vancomycin.


  • There are nearly 19,000 deaths each year due to invasive MRSA infections. (citation)
  • Patients with bloodstream infections or surgical site infections caused by MRSA have a higher risk of death compared with patients with infections caused by a strain of Staphylococcus aureus (staph) that does not have resistance to antibiotics. (citation)


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