What causes MRSE (Methicillin-Resistant Staphylococcus epidermidis) infection?

How MRSE Infection is Acquired

Methicillin-Resistant Staphylococcus epidermidis (MRSE) infection is primarily acquired through healthcare contact, particularly via implanted medical devices, but can also spread in community settings through direct skin-to-skin contact or contact with contaminated surfaces. 1, 2

Transmission Pathways

MRSE is part of the normal human skin flora but becomes problematic when it enters the body through breaks in the skin barrier. The main transmission routes include:

Healthcare-Associated Transmission

• Medical devices: MRSE has a strong ability to adhere to and form biofilms on implanted medical devices such as:

  • Intravascular catheters
  • Prosthetic joints
  • Heart valves
  • Vascular grafts 1, 2

• Healthcare environment:

  • Contaminated medical equipment
  • Environmental surfaces in healthcare facilities
  • Clothing of healthcare personnel 2

• Person-to-person transmission:

  • Skin of healthcare workers to patients
  • Between patients via healthcare workers' hands 2

Community-Associated Transmission

Similar to community-associated MRSA (CA-MRSA), MRSE can spread in community settings through:

• Direct skin-to-skin contact
• Sharing of personal items (towels, razors)
• Contact with contaminated surfaces 3

Risk Factors for MRSE Infection

Patient-Related Factors

• Immunocompromised status:

  • HIV/AIDS
  • Malignancy
  • Transplant recipients
  • Patients on immunosuppressive therapy 2

• Presence of indwelling devices:

  • Central venous catheters
  • Prosthetic heart valves
  • Joint prostheses 1, 2

• Recent hospitalization or healthcare facility exposure 2

• Prior antibiotic use, particularly beta-lactams 1

Microbiological Factors

• Antibiotic resistance: MRSE has acquired resistance to multiple antibiotics, making infections difficult to treat 2

• Biofilm formation: MRSE's ability to form biofilms on medical devices protects it from antibiotics and host immune responses 4

• Resistance mechanism: Similar to MRSA, MRSE carries the mecA gene that encodes for penicillin-binding protein 2a (PBP2a), conferring resistance to beta-lactam antibiotics 4

Prevention Strategies

Healthcare Settings

• Hand hygiene: Strict adherence to hand hygiene protocols by healthcare workers
• Contact precautions: For patients with known MRSE infections
• Environmental cleaning: Regular disinfection of surfaces and equipment
• Antimicrobial stewardship: Appropriate use of antibiotics to prevent further resistance 1

Device-Related Interventions

• Aseptic technique during device insertion
• Minimizing device use and duration when possible
• Proper care and maintenance of indwelling devices 2

Clinical Implications

MRSE infections are particularly concerning because:

• They often affect vulnerable patients (immunocompromised, critically ill)
• They're difficult to diagnose (may be dismissed as contaminants)
• They're challenging to treat due to antibiotic resistance
• They can cause serious infections including bacteremia, endocarditis, and device-related infections 2

Common Pitfalls in Managing MRSE

1. Dismissing S. epidermidis as a contaminant: While often a contaminant in blood cultures, persistent isolation of MRSE should prompt evaluation for true infection, especially in patients with implanted devices 2

2. Inadequate source control: Failure to remove infected devices when necessary can lead to persistent infection

3. Inappropriate antibiotic selection: Using beta-lactams alone against MRSE will likely fail; appropriate antibiotics like vancomycin, linezolid, or daptomycin should be considered for serious infections 1

4. Failure to recognize community spread: Like MRSA, MRSE can spread in community settings, particularly among individuals with risk factors 3

Understanding these transmission pathways and risk factors is essential for preventing and managing MRSE infections effectively.