Overview
Definition:
Methicillin-resistant Staphylococcus aureus (MRSA) is a type of bacteria that has developed resistance to certain antibiotics, specifically beta-lactam antibiotics including penicillin, methicillin, and oxacillin
Pediatric skin and soft tissue infections (SSTIs) caused by MRSA are a significant public health concern due to their potential for morbidity and spread
These infections commonly present as localized abscesses, cellulitis, or impetigo.
Epidemiology:
Community-acquired MRSA (CA-MRSA) strains are now the most common cause of S
aureus SSTIs in children, surpassing hospital-acquired strains in many regions
Factors contributing to the rise include increased skin-to-skin contact, poor hygiene, crowded living conditions, and sharing of personal items
Incidence varies geographically, but MRSA SSTIs are prevalent globally.
Clinical Significance:
MRSA skin infections in children can lead to severe local complications like abscesses, cellulitis, and bacteremia, and in rare cases, more serious invasive diseases such as pneumonia, osteomyelitis, endocarditis, and sepsis
Prompt and appropriate management is crucial to prevent these complications, reduce transmission, and guide effective antibiotic stewardship.
Clinical Presentation
Symptoms:
Localized pain and tenderness at the site of infection
Erythema and swelling
Presence of a pustule or boil, often with purulent drainage
Fever and malaise may be present, especially with more extensive infections
Symptoms can rapidly progress from a small red bump to a painful abscess.
Signs:
A fluctuant or palpable mass indicating an abscess
Erythematous, warm, and tender skin overlying the infected area
Purulent discharge expressed from the lesion
Possible surrounding cellulitis with ill-defined borders
Systemic signs of infection like fever (temperature >38.0°C or 100.4°F), tachycardia, or lethargy may be present in severe cases.
Diagnostic Criteria:
Diagnosis is typically made clinically based on the appearance of the lesion and epidemiological context
Definitive diagnosis requires laboratory confirmation by culture and susceptibility testing of purulent material obtained from the lesion
Clinical suspicion for MRSA is high in immunocompromised hosts, those with recent healthcare exposure, or in endemic communities.
Diagnostic Approach
History Taking:
Detailed history of lesion onset, progression, and associated symptoms
Inquiry about fever, chills, or systemic illness
Exposure history: contact with individuals with similar infections, participation in contact sports, attendance at daycare or school
Previous antibiotic use and response
Allergies
Underlying medical conditions (e.g., atopy, immunocompromise)
Recent hospitalizations or antibiotic use.
Physical Examination:
Thorough examination of the skin, paying attention to the morphology and extent of the lesion
Palpation for fluctuance and tenderness
Assessment of surrounding cellulitis
Evaluation for satellite lesions or multiple lesions
Examination of lymph nodes for regional adenopathy
General assessment for signs of systemic illness, including vital signs.
Investigations:
Culture and Gram stain of purulent material from the lesion is the gold standard for diagnosis and susceptibility testing
If bacteremia is suspected, blood cultures should be obtained
Complete blood count (CBC) with differential may show leukocytosis
Inflammatory markers like C-reactive protein (CRP) can be elevated
Imaging is rarely needed for uncomplicated SSTIs but may be considered for deep abscesses or suspected osteomyelitis (X-ray, ultrasound, MRI).
Differential Diagnosis:
Bacterial abscesses caused by other organisms (e.g., methicillin-susceptible Staphylococcus aureus (MSSA), Streptococcus pyogenes)
Folliculitis
Furuncle
Carbuncle
Hidradenitis suppurativa
Insect bites
Viral exanthems
Ecthyma
Allergic reactions.
Management
Initial Management:
The cornerstone of management for localized, uncomplicated MRSA skin abscesses is incision and drainage (I&D)
This provides source control and rapidly relieves pain and pressure
Prompt I&D is often preferred over antibiotics alone for fluctuant abscesses
Wound care includes cleaning, packing if necessary, and dressing changes.
Medical Management:
Antibiotics are indicated for patients with signs of systemic illness (fever, malaise), extensive cellulitis without a clear abscess, rapidly progressing infection, immunocompromised status, or failure of I&D alone
For uncomplicated SSTIs, oral antibiotics with MRSA coverage should be initiated
Common choices include trimethoprim-sulfamethoxazole (TMP-SMX), clindamycin, doxycycline, or linezolid
For severe infections or those with bacteremia, intravenous antibiotics such as vancomycin, linezolid, or daptomycin are necessary.
Surgical Management:
Incision and drainage (I&D) is the primary surgical intervention for fluctuant MRSA skin abscesses
The procedure involves making an incision into the abscess cavity to release purulent material, followed by gentle irrigation and debridement of any necrotic tissue
Packing of the cavity may be necessary to promote healing by secondary intention
Careful surgical technique is required to minimize scarring and promote functional recovery.
Supportive Care:
Pain management with analgesics such as acetaminophen or ibuprofen
Elevation of the affected limb to reduce swelling
Application of warm compresses to promote drainage and comfort
Strict hand hygiene and wound care to prevent spread and re-infection
Patient and family education on recognizing signs of worsening infection and proper wound care.
Complications
Early Complications:
Spread of infection to deeper tissues leading to cellulitis, fasciitis, or osteomyelitis
Bacteremia with metastatic seeding to distant sites (e.g., endocarditis, pneumonia, meningitis, septic arthritis)
Recurrence of the abscess
Sepsis.
Late Complications:
Chronic wound healing issues or scarring
Deformity if infection affects joint or bone
Persistent or recurrent infections
Development of MRSA colonization, increasing risk of future infections.
Prevention Strategies:
Promote meticulous hand hygiene practices among children and caregivers
Education on not sharing personal items (towels, razors, sports equipment)
Proper wound care for minor cuts and abrasions
Prompt recognition and treatment of skin lesions
Encourage showering after physical activities and sports
Judicious use of antibiotics to prevent resistance development.
Prognosis
Factors Affecting Prognosis:
Timeliness and appropriateness of treatment
Presence of systemic signs of infection
Underlying host immune status
Virulence of the specific MRSA strain
Development of complications like bacteremia or metastatic infection.
Outcomes:
With prompt and appropriate management, including I&D and targeted antibiotics when indicated, most children with MRSA skin infections have an excellent prognosis and achieve full recovery
Recurrence is possible if preventative measures are not maintained or if treatment is incomplete
Invasive MRSA infections carry a higher morbidity and mortality risk.
Follow Up:
Follow-up is recommended to ensure complete resolution of the infection, assess wound healing, and evaluate for any signs of recurrence or complications
For patients with severe infections or recurrent episodes, further evaluation for underlying risk factors or immunocompromise may be warranted
Education on prevention strategies should be reinforced at follow-up visits.
Key Points
Exam Focus:
MRSA is the most common cause of S
aureus SSTIs in children
Incision and drainage (I&D) is the primary treatment for fluctuant abscesses
Antibiotics are indicated for systemic illness, extensive cellulitis, or failure of I&D
Common oral antibiotics for MRSA SSTIs include TMP-SMX and clindamycin
Vancomycin is a first-line IV option for severe infections.
Clinical Pearls:
Always suspect MRSA in pediatric skin infections presenting as boils or abscesses, especially in community settings
Differentiate between a simple furuncle and a larger, fluctuant abscess requiring I&D
Do not prescribe antibiotics alone for a simple, fluctuant abscess
drainage is key
Reinforce hand hygiene and wound care education with families.
Common Mistakes:
Treating a simple, fluctuant MRSA abscess with antibiotics alone without drainage
Delaying I&D when indicated, leading to complications
Inadequate wound care and follow-up
Prescribing antibiotics that do not cover MRSA for suspected MRSA infections
Over-reliance on systemic antibiotics without source control.