What patients are at high risk for Methicillin-resistant Staphylococcus aureus (MRSA) infections due to co-morbidities?

High-Risk Comorbidities for MRSA Infection

Patients with immunosuppression, diabetes mellitus, chronic obstructive pulmonary disease, congestive heart failure, and those on hemodialysis are at significantly higher risk for MRSA colonization and subsequent infection. 1

Key Risk Factors for MRSA Infection

Patient Demographics and History

• Age ≥60 years significantly increases risk of MRSA infection and associated mortality 2
• Previous MRSA infection or colonization within the past year is one of the most reliable predictors for future MRSA infection 1
• Recent hospitalization (within the preceding year) increases risk of MRSA colonization 1
• Residence in long-term care facilities substantially increases MRSA risk 1

Medical Comorbidities

• Diabetes mellitus - particularly significant in diabetic foot infections 1, 3
• Chronic kidney disease, especially patients on hemodialysis 1, 3
• Chronic obstructive pulmonary disease (COPD) 1
• Congestive heart failure 1
• Immunosuppression from any cause (disease or medication-related) 1
• Hemiplegia has been identified as an independent risk factor 3
• Chronic liver failure 1

Healthcare Exposures

• Receipt of antibiotics within 3 months before admission, especially beta-lactams, carbapenems, and quinolones 1
• Prolonged hospital/chronic facility stays 1
• Recent invasive procedures 1, 3
• Presence of invasive medical devices (central venous catheters, hemodialysis catheters) 1
• Prior surgery, particularly recent major abdominal surgery 1, 3

Additional Risk Factors

• Open wounds or skin breakdown 1
• Total parenteral nutrition 1
• HIV infection 1
• Necrotizing pancreatitis 1

Special Populations at Increased Risk

Community-Associated MRSA Risk Groups

• Children <2 years old 1
• Athletes (particularly contact-sport participants) 1
• Injection drug users 1
• Homosexual males 1
• Military personnel 1
• Inmates of correctional facilities, residential homes, or shelters 1
• Veterinarians, pet owners, and pig farmers 1

Clinical Implications and Management

Empiric Antibiotic Selection

• Consider empiric MRSA coverage when:
  • Patient has prior history of MRSA infection/colonization 1
  • Local MRSA prevalence is high (>30% for moderate infections) 1
  • Infection is severe enough that treatment failure would pose unacceptable risk 1

Antibiotic Options for MRSA

• For serious infections: vancomycin, linezolid, daptomycin (except for pneumonia) 4
• For skin and soft tissue infections: trimethoprim-sulfamethoxazole, clindamycin, doxycycline 1
• Newer agents: ceftaroline, tedizolid, dalbavancin, and oritavancin 4

Infection Control Measures

• Implementation of MRSA monitoring programs 1
• Use of contact precautions for MRSA-colonized and MRSA-infected patients 1
• Proper cleaning and disinfection of equipment and environment 1
• Education of healthcare workers, patients, and families about MRSA 1

Pitfalls and Caveats

• MRSA strains may develop resistance to multiple antibiotics, including vancomycin in some cases 5
• Elderly patients (≥60 years) with MRSA bacteremia have significantly higher mortality rates 2
• Patients with multiple comorbidities have substantially worse outcomes with MRSA infection 2
• The distinction between healthcare-acquired and community-associated MRSA infections has become increasingly blurred 1
• Patients with diabetes and foot infections require special attention as MRSA is a common pathogen 1
• Some patients with MRSA colonization may clear their infection despite antibiotics not covering this organism, but this should not be relied upon 1