Methicillin-Resistant Staphylococcus Aureus (MRSA)
and Multidrug-Resistant Organisms (MDROs)


Multidrug-resistant organisms (MDROs) are bacteria that are not able be treated with certain types of antibiotics and require treatment with other medicines that may be less effective, more toxic, and more expensive. There are several types of MDROs that may be found in healthcare facilities, including carbapenem-resistantEnterobacteriaceae (CRE), methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-intermediate or vancomycin resistant Staphylococcus aureus (VISA/VRSA), and vancomycin-resistant Enterococci (VRE). It is possible to carry a MDRO in or on your body but not show any symptoms; this is called colonization. Symptoms of an active infection will depend on the type of organism, the site of infection, and individual risk factors.

Acinetobacter baumannii is a type of bacteria commonly found in soil and water that can become resistant to many commonly prescribed antibiotics. Infections caused by these bacteria rarely occur outside of healthcare settings and can cause a variety of diseases, ranging from pneumonia to serious blood or wound infections.

Enterobacteriaceae is a family of bacteria that include E. coli, Enterobacter, Klebsiella, Salmonella, and several other common types of bacteria. If these bacteria develop resistance to carbapenems, a class of antibiotics, they become carbapenem-resistant Enterobacteriaceae (CRE). CRE are very difficult to treat because they are usually resistant to almost all available antibiotics. CRE may cause a variety of infections ranging from gastrointestinal illness to pneumonia to invasive infections of the bloodstream or other body organs.

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-resistantStaphylococcus 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-resistantEnterococci (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.

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Estimated burden of MDROs in healthcare facilities in the United States:

  • Morbidity
    • 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 in Virginia.
    • According to the latest CDC National and State HAI Progress Report, acute care hospitals have experienced an 8% 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.
  • Mortality
    • 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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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 Public Reporting 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).

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Prevention Strategies for Healthcare Providers

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.

CDC MRSA Prevention Collaborative Toolkit – contains background on epidemiology of MRSA as well as core and supplemental prevention strategies

Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA) for the Treatment of Methicillin-Resistant Staphylococcus Aureus Infections in Adults and Children (2011)

SHEA/IDSA Compendium of Strategies to Prevent Healthcare-Associated Infections in Acute Care Hospitals – MRSA

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Tools and Resources

General Resources – MDROs and Drug Resistance
ABCs of Antibiotics – an infographic on antibiotic resistance (APIC)

Antibiotic Resistant Threats in the United States, 2013 (CDC) – report that highlights 17  antibiotic-resistant bacteria and fungi that pose urgent, serious, or concerning threats to human health in the United States

Antibiotic stewardship webpage

CDC Grand Rounds: Getting Smart About Antibiotics (August 21, 2015)

CDC Vital Signs report (March 2014) – Antibiotic Prescriptions in Hospitals: Proceed with Caution

  • Information on antibiotic prescribing practices in hospitals and ways to improve these practices to prevent allergic reactions, drug-resistant infections, and Clostridium difficile diarrhea.
  • MMWR March 4, 2014 science behind the CDC Vital Signs report on improving antibiotic prescription practices for hospitalized patients.

CDC Vital Signs report (August 2015) – Stop Spread of Antibiotic Resistance

  • Information on antibiotic resistance and the need for regional coordination to improve antibiotic use and infection control activities so that patients are better protected.
  • MMWR August 4, 2015: science behind the CDC Vital Signs report on estimated effects of a coordinated approach for action to reduce antibiotic-resistant infections in healthcare facilities.

Drug Resistance and Antibiotic Stewardship fact sheet

Eastern Virginia Medical School (EVMS) – educational resources for healthcare consumers about antibiotic resistance

  • Nighmare Bacteria: The Threat of Antibiotic Resistance (video)
  • Nightmare Bacteria: The Discovery of Penicillin & Emergence of MRSA (video)
  • Nightmare Bacteria: Tracking the Patterns (video)
  • “Danger Ahead: The Rise in Antibiotic Resistance” (article)

NHSN Multidrug-resistant Organism and Clostridium difficile Infection (MDRO/CDI) Module  – protocol, training, forms, analysis resources, and other materials for performing infection surveillance, laboratory-identified (LabID) event reporting, prevention process and active surveillance testing outcome measures. Prevention process measures include hand hygiene and gown and gloves use adherence. MDROs monitored include MRSA, VRE,Klebsiella spp., and Acinetobacter spp.  Click on the appropriate healthcare setting and select the MDRO/CDI link to access the training, protocols, forms, analysis resources, and other support materials

For more patient resources, please see the Consumer and Public Information page

Acinetobacter baumannii
APIC Guide to the Elimination of Multidrug-Resistant Acinetobacter baumannii Transmission in Healthcare Settings

CDC website – Acinetobacter

Carbapenem-resistant Enterobacteriaceae (CRE)

CDC toolkit

CDC website – CRE

CDC Vital Signs Report: Making Health Care Safer – Stop Infections from Lethal CRE Germs Now (March 2013) – information on what CRE are, how they are spread, and what the federal government, states and communities, healthcare administrators, healthcare providers, and patients can do to prevent them

CRE in Virginia Hospitals: Results from Laboratory and Hospital Infection Preventionist Surveys (July 2014) – results from surveys administered in 2013 to Virginia laboratories and hospital (acute care and long-term acute care) infection preventionists. Describes current CRE identification, surveillance, and prevention practices in Virginia hospitals.

CRE in Virginia – Results from a Survey of Hospital Infection Preventionists (September 2014) – Slides from a VDH webinar presented on September 24, 2014 that shares results from CRE surveys of laboratorians and hospital infection preventionists

CRE: Detect and Protect (April 2013) – Powerpoint presentation developed by VDH for healthcare personnel in acute care or long-term care facilities to provide an overview of CRE epidemiology, surveillance, and prevention strategies

CRE fact sheet for assisted living facilities and nursing homes

General CRE fact sheet

Guidance for Control of Infections with Carbapenem-Resistant or Carbapenemase-Producing Enterobacteriaceae in Acute Care Facilities, MMWR, March 20, 2009

Health Advisory from CDC: New Carbapenem-Resistant Enterobacteriaceae Warrant Additional Action by Healthcare Providers (February 14, 2013)

Morbidity and Mortality Weekly Report (MMWR) – March 6, 2013 – more detailed information on methodology of Vital Signs report

Summary Recommendations for Acute and Long-Term Care Facilities for Control of CRE (April 2013) – document developed by VDH that summarizes the 2012 CDC CRE toolkit and discusses when to call the local health department

APIC Guide to the Elimination of Methicillin-Resistant Staphylococcus Aureus Transmission in Hospital Settings, Second Edition, 2010

APIC Guide to the Elimination of Methicillin-Resistant Staphylococcus Aureus (MRSA) in the Long-Term Care Facility, 2009

CDC website – MRSA

General MRSA fact sheet

MRSA fact sheet for assisted living facilities and nursing homes

OSHA Hospital e-Tool: MDRO/MRSA module – information to help stop the spread of MRSA among employees and others working in healthcare and other industries.

Personal prevention of MRSA skin infections – for patients

SHEA Patient Education Guide (MRSA)– fact sheet that educates patients and their families about 7 types of HAIs (including MRSA) and how to work with healthcare professionals to prevent them.

Vancomycin-resistant Enterococci (VRE)
CDC website – VRE

SHEA Patient Education Guide (VRE) – fact sheet that educates patients and their families about 7 types of HAIs (including VRE) and how to work with healthcare professionals to prevent them.

General VRE fact sheet

VRE fact sheet for assisted living facilities and nursing homes

Vancomycin-intermediate or Vancomycin-resistant Staphylococcus Aureus (VISA/VRSA)
CDC clinical reminder (2010) – discusses the important role of clinical laboratories in the diagnosis of VRSA cases to ensure prompt recognition, isolation, and management by infection control personnel

CDC website –VISA/VRSA

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(Gorwitz RJ et al. Journal of Infectious Diseases. 2008:197:1226-34.)

Magill SS, Edwards JR, Bamberg W, et al. Multistate Point-Prevalence Survey of Health Care–Associated Infections. N Engl J Med 2014;370:1198-208. To access the full article, link through this website: (click top link)