Methicillin-resistant staphylococcus aureus, commonly known as MRSA, is a form of contagious bacterial infection. People sometimes call it a superbug because it is resistant to numerous antibiotics. This resistance makes it challenging to treat.
In healthy people, MRSA does not usually cause a severe infection, but older people, individuals with health conditions, and those with a weakened immune system may be at risk.
Experts consider this infection to be a “serious” threat. If it develops resistance to other antibiotics, it will be harder to treat and may become an “urgent” threat.
In this article, find out what MRSA is, why it happens, and why it causes concern.
What is a superbug? Click here to learn more.
MRSA is a common and potentially serious infection that has developed resistance to several types of antibiotics. These include methicillin and related antibiotics, such as penicillin, vancomycin, and oxacillin. This resistance makes MRSA difficult to treat.
Methicillin is an antibiotic that is related to penicillin. It was once effective against Staphylococci (staph), a type of bacteria.
Over time, staph bacteria have developed a resistance to penicillin-related antibiotics, including methicillin. These resistant bacteria are called methicillin-resistant staphylococcus aureus, or MRSA.
Although doctors can no longer use methicillin to treat MRSA, this does not mean that the infection is untreatable. Some antibiotics are effective in treating it.
What is antibiotic resistance? Find out here.
Staph bacteria cause infections that can lead to complications ranging in severity from mild to life threatening.
- bloodstream infections
- surgical site infections
In some cases, MRSA can be life threatening.
MRSA infections can be healthcare-associated or community-associated. In 2008, about 86% of all invasive MRSA infections in the U.S. were healthcare-associated. This classification means that they occurred or started in a healthcare setting.
The type of treatment for MRSA will depend on the following factors:
- the type and location of the infection
- the severity of the symptoms
- the antibiotics to which the strain of MRSA responds
The bacteria that cause MRSA are resistant to some but not all antibiotics. A doctor will prescribe medication that is suitable for the particular infection that occurs.
A person should make sure that they take the whole course of antibiotics exactly as the doctor prescribes. Some people stop taking the drugs after the symptoms disappear, but this can increase the risk of the infection coming back and becoming resistant to treatment.
MRSA results from infection with bacterial strains that have acquired resistance to particular antibiotics.
MRSA is contagious
MRSA can spread from person to person through direct skin-to-skin contact or when a person with MRSA bacteria on their hands touches an object that another person then touches.
MRSA bacteria can survive for a long time on surfaces and objects, including fabrics and door handles.
In 2000, scientists investigated how long resistant staph could survive on five common hospital fabrics. They injected the fabrics with colony-forming units of staph and observed the reactions over the following days.
They found that the bacteria could survive for:
- 4–21 days on 100% smooth cotton (clothing)
- 2–14 days on 100% cotton terry (towels and washcloths)
- 1–3 days on a 60% cotton, 40% polyester blend (scrub suits, lab coats, and clothing)
- 1–40 days on 100% polyester (privacy drapes, curtains, and clothing)
- 40 to longer than 51 days on 100% polypropylene plastic (splash aprons)
These results demonstrate the need for thorough contact control and meticulous disinfection procedures to limit the spread of bacteria.
MRSA frequently causes illness in people with a compromised immune system who spend time in the hospital and other healthcare facilities.
This type is called healthcare-associated MRSA or hospital-acquired MRSA.
MRSA is more likely to happen in a hospital because:
- Infections can easily spread when there are many people in a limited space.
- People in the hospital may have a higher risk of contracting the infection.
- When people are older or have certain health conditions, they may be less able to resist infection.
A person will have a higher risk of developing healthcare-associated MRSA in the hospital if they have had surgery recently or if they have:
- a weakened immune system
- an open wound
- a catheter or intravenous drip
- burns or cuts to the skin surface
- a severe skin condition
- frequent antibiotics as part of their treatment
A person may have a weakened immune system if they:
- have been a patient in a hospital for a long time
- have had an organ transplant
- are undergoing kidney dialysis
- are receiving cancer treatment or have certain types of cancer
- are using medications that affect immune function
- inject recreational drugs
- have had surgery within a year of previous hospitalization
MRSA is less common outside a healthcare setting. If it does occur, it is more likely to be a skin infection, although some people develop pneumonia and other infections.
Factors that increase the risk of developing community-associated MRSA include:
- living with a lot of people, such as on a military base, in jail, or on a campus
- having regular skin-to-skin interaction with other people, for example, in contact or collision sports, such as soccer
- doing a job or hobby that increases the risk of cuts or grazes to the skin
- regularly injecting drugs
- having low adherence to personal or environmental hygiene
- previous antibiotic use
People can reduce the risk by practicing appropriate hand washing, keeping wounds clean, avoiding sharing personal items — such as towels and razors, and seeking early treatment if any symptoms of an infection appear.
Children can develop MRSA through an open wound. Find out how to recognize it and what to do.
The symptoms of MRSA will depend on the area of the body that is infected.
Many people carry MRSA bacteria in their mucosa, for instance, inside the nose, but they may never develop symptoms that indicate an active infection.
Staph skin infections, including MRSA, appear as a bump or sore area of the skin that can resemble an insect bite.
The infected area might be:
Symptoms of a serious MRSA infection in the blood or deep tissues may include:
- a fever of 100.4°F or higher
- muscle pain
- swelling and tenderness in the affected body part
- chest pain
- a cough
- a headache
- a rash
- inability to heal wounds
Tips to prevent MRSA depend on whether it is healthcare-associated or community-associated:
Preventing healthcare-associated MRSA infection
The following guidelines can help patients, healthcare workers, and visitors prevent MRSA infections from spreading in the hospital:
- using soap and water or an alcohol-based hand rub
- covering any wounds with a clean dressing
- following the advice of healthcare professionals about using or caring for catheters and other devices
- disposing of dressings and other material responsibly
It may be necessary for a patient with an MRSA infection to stay in their room until treatment is complete.
Preventing community-associated MRSA infection
People can reduce the risk of community-associated MRSA outside of hospitals by:
- washing the hands regularly
- keeping the fingernails short
- avoiding popping or pricking spots or skin lesions
- washing the hands after changing a dressing or cleaning a wound
- avoiding sharing soaps, lotions, creams, and cosmetics with others
- avoiding sharing towels and uniforms
- avoiding sharing personal items, such as razors, nail files, toothbrushes, combs, and hairbrushes
- using disinfectants, detergents, and other products to keep surfaces clean
- laundering fabric items before sharing them with another person
Experts are concerned about MRSA and other bacteria that have developed resistance to certain antibiotics. However, a growing awareness of hygiene procedures appears to have helped reduce the number of cases.
In 2011, there were 80,461 severe MRSA infections in the U.S. and 11,285 deaths.
However, from 2005 to 2014, the Centers for Disease Control and Prevention (CDC) estimate that the overall number of invasive MRSA infections fell by 40%, and the number of cases that started in healthcare settings fell by 65%. They note that this decrease is probably due to improved guidelines relating to hygiene and contact.
If I have had MRSA once, does that mean that I can get it more easily or more severely next time?