What does being MRSA (Methicillin-resistant Staphylococcus aureus) positive mean?

MRSA Positive: Understanding Methicillin-Resistant Staphylococcus aureus Infection

MRSA positive means you are infected or colonized with a strain of Staphylococcus aureus bacteria that is resistant to methicillin and other common antibiotics, which can cause serious infections requiring specific antibiotic treatment and infection control measures. 1

What is MRSA?

MRSA (Methicillin-resistant Staphylococcus aureus) is a type of bacteria that has developed resistance to many antibiotics, including:

• Methicillin
• Other beta-lactam antibiotics (penicillins and cephalosporins)
• Often multiple other antibiotic classes (erythromycin, tetracycline, etc.) 1

There are two main types of MRSA:

1. Hospital-Associated MRSA (HA-MRSA):

   • Acquired in healthcare settings
   • Often resistant to multiple antibiotics
   • Typically causes more severe infections

2. Community-Associated MRSA (CA-MRSA):

   • Acquired in community settings
   • Genetically distinct from HA-MRSA
   • Often carries the Panton-Valentine Leukocidin (PVL) gene, which can make infections more aggressive 1

MRSA Colonization vs. Infection

Being MRSA positive can mean one of two things:

MRSA Colonization:

• Bacteria are present on your body (commonly in the nose, throat, armpits, or groin) without causing illness
• You are a carrier who can potentially spread MRSA to others
• Approximately 30% of people carry Staphylococcus aureus in their nose, with a smaller percentage carrying MRSA
• Being colonized increases your risk of developing an actual MRSA infection 2

MRSA Infection:

• Bacteria have invaded tissues and are causing active disease
• Common MRSA infections include:
  • Skin and soft tissue infections (most common)
  • Pneumonia (particularly severe with PVL-positive strains)
  • Bloodstream infections
  • Surgical site infections
  • Endocarditis 1

Clinical Implications of Being MRSA Positive

Health Risks:

• Higher risk of developing invasive infections
• Infections may be more difficult to treat due to antibiotic resistance
• Potentially higher mortality rates, especially with invasive infections like pneumonia or bloodstream infections 1, 3

Treatment Challenges:

• Standard antibiotics like methicillin, oxacillin, and most cephalosporins will not work
• Treatment requires specific antibiotics such as:
  • Vancomycin (traditional first-line therapy)
  • Linezolid
  • Daptomycin
  • Combination therapies may be needed for severe infections 1

Infection Control Measures:

• Healthcare facilities implement special precautions for MRSA-positive patients:
  • Contact isolation
  • Dedicated equipment
  • Enhanced environmental cleaning
  • Healthcare worker hand hygiene
• These measures help prevent spread to other vulnerable patients 1

Management of MRSA Positivity

For Colonization:

• Decolonization may be recommended in certain situations:
  • Recurrent MRSA infections
  • Before certain surgeries
  • In outbreak settings
  • For healthcare workers
• Decolonization typically involves:
  • Nasal mupirocin ointment
  • Chlorhexidine body washes
  • Sometimes oral antibiotics 2, 4

For Active Infection:

• Prompt identification and appropriate antibiotic therapy
• For mild skin infections: incision and drainage may be sufficient
• For severe infections: intravenous antibiotics effective against MRSA
• For pneumonia: aggressive supportive care often needed, especially with PVL-positive strains 1

Special Considerations

PVL-Positive MRSA:

• PVL is a toxin produced by some MRSA strains
• Associated with more aggressive infections, especially pneumonia
• Symptoms include high fever, rapid progression, and respiratory failure
• Requires aggressive treatment and intensive care support 1

Community vs. Hospital MRSA:

• CA-MRSA often causes skin infections in otherwise healthy people
• HA-MRSA more commonly affects people with healthcare exposure or weakened immune systems
• Treatment approaches may differ based on the type 1

Prevention of MRSA Spread

• Regular handwashing with soap and water
• Covering wounds with clean, dry bandages
• Not sharing personal items like towels or razors
• Cleaning shared equipment (especially in gyms)
• Following healthcare provider instructions if you are MRSA positive 5

Being MRSA positive requires attention to prevent both personal complications and transmission to others. With proper management and treatment, most MRSA infections can be successfully treated, though the bacteria may persist in a colonized state.