MRSA (Methicillin-Resistant Staphylococcus aureus)

What MRSA is

Staphylococcus aureus (staph) commonly lives on the skin and in the nose. Over time, some strains became resistant to beta-lactam antibiotics, including methicillin, penicillin, amoxicillin, oxacillin and most cephalosporins. These are called MRSA. MRSA is not more aggressive than ordinary staph in most cases, but fewer antibiotics work against it.

There are two broad types:

How MRSA spreads

• direct skin-to-skin contact with an infected wound or a carrier
• sharing towels, razors, sports equipment or clothing
• contaminated surfaces, especially in gyms and locker rooms
• in healthcare settings, through hands and equipment

Risk is higher with the "5 Cs": Crowding, frequent skin Contact, Compromised skin (cuts and scrapes), Contaminated items and lack of Cleanliness.

Symptoms

MRSA skin infection

• a red, swollen, painful bump, often like a pimple or boil
• warm to the touch
• filled with pus or draining fluid
• often with a yellow or white center or head
• may be mistaken for a spider bite
• sometimes fever

See boils and abscess.

Invasive MRSA infections

• Bloodstream infection and sepsis: fever, chills, low blood pressure, confusion
• Pneumonia: can be severe, especially after flu
• Bone and joint infections (osteomyelitis and septic arthritis): deep pain, swelling and fever
• Heart valve infection (endocarditis)
• Surgical wound infections

Diagnosis

MRSA is confirmed by culture: a swab or sample of pus, blood, sputum or other fluid is grown in the lab and tested against antibiotics. Rapid PCR tests can detect MRSA within hours, including nasal swabs used to screen hospital patients.

Treatment

Skin abscesses

• Incision and drainage: the most important treatment for an abscess. A doctor numbs the area, makes a small cut and drains the pus. Do not squeeze or cut it yourself
• Antibiotics are added for larger abscesses, spreading cellulitis, fever, multiple sites, very young or old patients, or weak immunity. Oral options that usually work against MRSA include trimethoprim-sulfamethoxazole, doxycycline, clindamycin and linezolid
• keep the wound covered and follow up if it does not improve within 48 to 72 hours

Serious infections

Hospital treatment with IV antibiotics such as vancomycin or daptomycin, removal of infected lines or devices, and surgery to drain or clean infected tissue.

Recurrent infections

When boils keep coming back, doctors may recommend decolonization: mupirocin ointment in the nose and chlorhexidine body washes for several days, sometimes for all household members, along with cleaning personal items and surfaces.

Prevention

• wash hands with soap and water or use alcohol-based hand sanitizer
• keep cuts and scrapes clean and covered until healed
• do not share towels, razors, clothing or sports equipment
• shower after sports and wash uniforms in hot water
• clean shared gym equipment before and after use
• take antibiotics only when prescribed and finish the course as directed
• in hospitals, follow hand hygiene and ask staff if they have washed their hands

Frequently asked questions

What does MRSA look like?

An MRSA skin infection usually looks like a red, swollen, painful bump or boil that is warm and may have a yellow or white center filled with pus. It is often mistaken for a spider bite. Spreading redness or fever suggests the infection is getting worse.

How do you get MRSA?

MRSA spreads through skin contact with an infected wound or a carrier, and by sharing items such as towels, razors and sports equipment. It is more common in hospitals, gyms, locker rooms, prisons, military settings and households where someone has it.

Is MRSA contagious?

Yes. MRSA can spread through direct contact and contaminated items. Covering wounds, washing hands and not sharing personal items greatly reduce spread. People who carry MRSA without symptoms can still pass it on.

Can MRSA be cured?

Yes. Most MRSA skin infections are cured by draining the abscess, sometimes with antibiotics that still work against it. Serious infections need hospital treatment with IV antibiotics. Carriage can come back, and decolonization helps people with recurrent infections.

Is MRSA dangerous?

Most MRSA infections are skin infections that respond well to treatment. MRSA can be dangerous when it enters the bloodstream, lungs, bones or heart valves, especially in people who are hospitalized, older or have weak immunity.