How is MRSA Spread in Hospitals?

For Healthcare Professionals

October 14, 2019


One of the first “superbugs,” MRSA has been a major concern for hospitals for nearly 60 years. MRSA is a common bacterium that can cause deadly infections, but its antibiotic-resistant nature makes those infections difficult to treat — especially in healthcare environments with vulnerable patient populations.

Thanks to better screening and prevention, hospital-acquired MRSA infections have declined significantly in recent years, but the CDC still lists it among the top “Antibiotic Resistance Threats in the United States.” Roughly 80,461 people develop severe MRSA infections each year, and 11,285 of them die.

How is MRSA spread in hospitals, and how can potentially fatal staph infections be prevented? 

What Is MRSA? 

MRSA is a strain of Staphylococcus aureus (or staph), a common bacteria that people carry on their skin, particularly the moist skin inside their noses. When staph finds a way into the body it can cause painful skin infections that produce open boils or cellulitis. In cases where staph enters the lungs or bloodstream, it can cause deadly infections in major organs, joints and bones.

Minor boils or abscesses caused by MRSA can sometimes be treated by simply draining the site, but more serious infections require antibiotics. Therein lies the problem with MRSA — doctors are running out of effective antibiotics to treat it.

Scientists first discovered S. aureus in the 1800s, but there were no medications to treat it until the 1940s, when antibiotic medicines like penicillin were first introduced. Over the next couple of decades, S. aureus bacterium began to evolve and develop a resistance to certain antibiotics. Methicillin, a form of penicillin, was introduced in 1959 to treat staph infection, but within a few years, new strains developed that could resist the new drug as well. These strains are called methicillin-resistant Staphylococcus aureus, or MRSA.

If caught early enough, MRSA can still be treated by several other antibiotics, including vancomycin. In 2002, scientists discovered vancomycin-resistant S. aureus strains, thankfully thus far, infection cases of this nature have been rare.

How Is MRSA Spread in Healthcare Environments?

MRSA infections occur in even the cleanest hospitals or nursing homes. That’s because MRSA is typically spread by people, and hospitals are full of patients, visitors, and healthcare workers who might unknowingly carry and transmit the bacteria.

MRSA is usually spread by direct contact with:


  • an infected wound
  • contaminated hands
  • contaminated surfaces or linens
  • a “colonized” person — someone who carries MRSA but does not have signs of an infection (even a healthcare worker)


Approximately 30 percent of people carry staph bacteria in their nasal passages, according to the CDC, and two percent carry MRSA in their noses. MRSA colonization rates are higher among hospital patients than in the general population. The CDC estimates that roughly 5 percent of inpatients carry MRSA, and one study found that up to 13 percent of ICU patients are MRSA carriers on admission.

Most of those people never know they’re colonized, because they never get sick, but they can easily transmit staph to others. With one sneeze or absentminded wipe of the nose, they can spread the bacteria to others — or to themselves. DNA tests reveal that roughly 80 percent of MRSA wound infections are caused by MRSA bacteria from the person’s own nose.

Hospital patients are at a greater risk of MRSA infections than the general population, because MRSA needs a way into the body to cause illness. Wounds, burns, and surgical sites make patients vulnerable to MRSA infection. So does invasive medical equipment, such as feeding tubes, IV drips, ventilators, catheters, and even intravenous medications. 

At the same time, hospital patients might have other serious health problems that compromise their immune system’s ability to fight the bacteria. They’re also positioned in close quarters with a large group of people and touched regularly by healthcare workers.

An Ounce of Prevention

Most MRSA infections can be successfully treated, just not with first-line antibiotics. However, many people don’t recover, and with more frequent use of second-line treatments, there is a higher chance this superbug will learn to resist them too. As staph bacteria continue to evolve, MRSA could become an even bigger problem for hospitals and communities. 

The best way to beat MRSA is to stop infections before they start. Yet, even as staph infection prevention becomes more important than ever, progress has stalled. Hospital-acquired MRSA bloodstream infections declined steadily from 2005 to 2013, dropping 17.1 percent per year, according to the CDC. From 2013 to 2016, no significant changes were detected. (The CDC will plans to publish new MRSA data later this year.)

Understanding how MRSA spreads is the first step to better prevention, and the CDC recommends that hospitals educate patients and workers about how to prevent infection. Healthcare providers should follow proper prevention protocols, including proper handwashing and glove use and implementing evidence-based guidelines for device- and procedure-related infections. The CDC also recommends that whenever possible, hospitals should use single-use medical equipment (i.e., disposable digital thermometers) or dedicated patient-care equipment (e.g., a blood pressure cuff or stethoscope that’s only used on one person). At the very least, equipment should be properly cleaned and disinfected in between patients.

For MRSA-colonized or infected patients, the CDC recommends that hospitals use contact precautions, including the use of personal protective clothing (gowns, caps, masks) for healthcare workers and visitors. However, the CDC acknowledges that some studies have questioned the efficacy of contact precautions, and suggests that hospitals take additional prevention measures, including decolonizing high-risk patients.

Skin can be decolonized using CHG antiseptic wipes on the surgical site prior to surgery, but since MRSA is most likely to colonize in the nose, that might not be enough to prevent infection. Nasal decolonization can be achieved with antibiotic ointments, such as mupirocin, but MRSA is becoming resistant to those medications as well. Alternatively, nasal antiseptic products like Nozin® Nasal Sanitizer® antiseptic may also reduce the risk of MRSA infections without contributing to superbug resistance.

The CDC recommends a decolonization protocol — CHG wash or wipes, plus an intranasal anti-staphylococcal antibiotic/antiseptic — for all patients undergoing high-risk surgeries, all ICU patients, and any non-ICU patient with CVC or a midline catheter. Both the Society for Healthcare Epidemiology of America (SHEA) and Health Research and Educational Trust (HRET) also support MRSA decolonization for high-risk patients.

The Case for Universal Decolonization

Medical researchers, healthcare organizations, and informed patients all deserve a pat on the back for working to decrease the transmission of MRSA, but as progress has plateaued, new strategies should be considered. These strategies should focus on eliminating MRSA at the source, including in individuals who are spreading the bacterium without displaying symptoms themselves. 

For example, studies suggest universal decolonization could further reduce MRSA infection rates, especially in intensive care units. In one study by the University of California Irvine — involving 43 hospitals, 74 ICUs and 74,256 patients — researchers evaluated three MRSA-prevention strategies: 


  • MRSA screening and isolation of infected/colonized patients
  • MRSA screening and targeted decolonization of infected/colonized patients
  • Universal decolonization/no screening


The study found that universal decolonization was significantly more successful at reducing bloodstream MRSA infections than either targeted decolonization or screening/isolation. That’s good news for patients, and for healthcare workers who might be able to avoid the time-consuming task of donning protective clothing before entering certain patient rooms.

Universal decolonization is just one way to potentially reduce MRSA infections. As hospitals continue to introduce innovative staph prevention protocols, and as the CDC and other research organizations continue studying this resilient bacteria, the medical community will continue finding ways to reduce the spread of MRSA.


Health Professionals:
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