Overview
Definition:
Methicillin-resistant Staphylococcus aureus (MRSA) colonization refers to the presence of MRSA on the skin or in the nares without causing active infection
Eradication protocols aim to eliminate this carriage state to prevent subsequent invasive infections in the individual or transmission to others.
Epidemiology:
Pediatric colonization rates vary geographically and by setting, with higher prevalence in community-acquired MRSA (CA-MRSA) strains
Nasal colonization is most common, but skin, groin, and axilla can also harbor MRSA
Risk factors include frequent healthcare contact, participation in contact sports, and crowded living conditions.
Clinical Significance:
Asymptomatic colonization is a precursor to invasive MRSA infections, including skin and soft tissue infections (SSTIs), pneumonia, and bacteremia
Eradication is crucial in specific pediatric populations, such as those with atopic dermatitis, recurrent SSTIs, or those undergoing invasive procedures, to reduce infection risk and prevent transmission in healthcare and community settings.
Indications For Eradication
High Risk Patients:
Children with recurrent MRSA skin and soft tissue infections
Individuals with invasive devices (e.g., catheters, shunts)
Patients undergoing elective surgery or chemotherapy.
Household Contacts:
Consider eradication if a household member has recurrent MRSA infections or if there are vulnerable individuals in the home.
Outbreaks:
During MRSA outbreaks in schools, daycares, or healthcare facilities to limit transmission.
Specific Conditions:
Children with atopic dermatitis, cystic fibrosis, or other conditions predisposing to MRSA colonization and infection.
Diagnostic Approach
Specimen Collection:
Nasal swabs (anterior nares) are the gold standard for detecting colonization
Swabs from other sites (e.g., wounds, skin lesions, groin) may be collected if clinically indicated.
Laboratory Testing:
Cultures should be performed on appropriate media
Identification of Staphylococcus aureus and susceptibility testing for methicillin resistance (using oxacillin or cefoxitin disc diffusion or agar dilution) are essential
Molecular methods (e.g., PCR) can also detect the mecA gene.
Interpretation:
Positive cultures for MRSA confirm colonization
Negative cultures do not entirely rule out transient colonization, but are generally reliable
Repeat testing may be considered if clinical suspicion remains high.
Eradication Protocols
Nasal Decolonization:
Mupirocin 2% ointment applied intranasally twice daily for 5-7 days is the mainstay
Bacitracin or retapamulin are alternatives
Application should cover the anterior nares.
Skin Decolonization:
Antimicrobial washes (e.g., chlorhexidine gluconate 4% or dilute bleach baths) can be used for widespread skin carriage
Dilute bleach baths (1/4 cup bleach per 40 gallons water) for 10-15 minutes, 2-3 times weekly, are effective.
Systemic Antibiotics:
Rarely indicated for colonization alone
Considered for widespread or refractory colonization, or in conjunction with treatment of active infection
Oral antibiotics like trimethoprim-sulfamethoxazole or doxycycline may be used, but are associated with resistance development and side effects.
Environmental Decontamination:
Emphasis on hand hygiene, surface cleaning, and laundry practices to prevent re-colonization and transmission
Disinfection of personal items like razors, towels, and sports equipment.
Considerations In Pediatrics
Age Appropriateness:
Dosages and formulations for topical agents must be age-appropriate
Mupirocin is generally safe in infants and children
Dilute bleach baths require parental supervision.
Adherence:
Protocols require strict adherence by caregivers and children
Education on proper application techniques and duration is crucial
Written instructions and visual aids are beneficial.
Resistance Monitoring:
Potential for resistance development to topical agents, especially with prolonged or improper use
Surveillance and judicious use of antibiotics are important.
Follow Up:
Post-eradication cultures may be considered after completion of therapy to confirm clearance, especially in high-risk individuals or those with recurrent infections
Repeat eradication attempts may be necessary if colonization persists.
Complications Of Eradication Attempts
Topical Resistance:
Development of resistance to mupirocin or other topical agents, limiting future treatment options.
Allergic Reactions:
Contact dermatitis or other hypersensitivity reactions to topical antimicrobials or skin cleansers.
Disruption Of Normal Flora:
Alteration of the skin microbiome, potentially increasing susceptibility to other pathogens.
Treatment Failure:
Persistence of colonization despite adherence to protocols, requiring re-evaluation of the regimen or consideration of alternative strategies.
Key Points
Exam Focus:
Understand indications for MRSA eradication in pediatric patients
Recall the standard regimen for nasal decolonization (mupirocin)
Differentiate between topical and systemic approaches.
Clinical Pearls:
Emphasize patient/caregiver education for adherence
Consider skin and environmental decontamination alongside nasal treatment
Use systemic antibiotics judiciously for colonization alone.
Common Mistakes:
Incorrect dosage or duration of topical antibiotics
Underestimating the importance of environmental control and hand hygiene
Over-reliance on systemic antibiotics for asymptomatic colonization.