NCLEX Review Guide: Impetigo in Pediatric Patients

Definition and Causative Agents

• Impetigo is a highly contagious superficial bacterial skin infection commonly affecting children ages 2-5 years, characterized by honey-colored crusted lesions or fluid-filled vesicles. It primarily affects the face (particularly around the nose and mouth) and extremities, and can spread through direct contact with lesions or contaminated objects.
• Two primary causative organisms are Staphylococcus aureus and Group A beta-hemolytic streptococci (Streptococcus pyogenes), with S. aureus being the most common pathogen in both bullous and non-bullous impetigo types.

Types of Impetigo

• Non-bullous impetigo (impetigo contagiosa): The most common form (70% of cases), characterized by small red papules that rapidly evolve into vesicles and pustules that rupture and form the classic honey-colored crusts. Primarily caused by S. aureus or Streptococcus pyogenes.
• Bullous impetigo: Characterized by fragile, fluid-filled bullae (blisters) that rupture easily, leaving a thin, varnish-like coating. Almost exclusively caused by S. aureus strains that produce exfoliative toxin.
• Ecthyma: A deeper form of impetigo that extends into the dermis, causing painful fluid or pus-filled sores that develop thick crusts and can leave scars. Usually caused by Group A streptococci, sometimes with S. aureus.

Signs and Symptoms

• Initial presentation includes erythematous macules that progress to vesicles or pustules, which rupture and develop into the characteristic honey-colored crusts with surrounding erythema. Lesions are typically painless but may be pruritic (itchy).
• Bullous impetigo presents with clear fluid-filled vesicles that enlarge to form flaccid bullae up to 2 cm in diameter. After rupturing, they leave a thin, varnish-like coating or crust with a collarette of skin around the periphery.
• Regional lymphadenopathy may be present, particularly with more extensive infections. Systemic symptoms like fever are uncommon unless there's a secondary infection or complication.

Risk Factors and Predisposing Conditions

• Children aged 2-5 years are most commonly affected due to immature immune systems, frequent skin trauma from play, and close contact in daycare or school settings.
• Predisposing factors include poor hygiene, crowded living conditions, warm humid climate, skin trauma (cuts, insect bites, abrasions), and pre-existing skin conditions like atopic dermatitis, scabies, or pediculosis.
• Children with compromised immune systems, diabetes mellitus, or malnutrition have increased susceptibility to impetigo and may develop more severe infections.

Diagnostic Approach

• Diagnosis is primarily clinical, based on the characteristic appearance of lesions. In typical cases, laboratory tests are not necessary for diagnosis.
• When diagnosis is uncertain or in cases of treatment failure, bacterial culture and sensitivity testing of exudate from intact vesicles or from beneath crusts can identify the causative organism and guide antimicrobial therapy.
• Differential diagnoses include contact dermatitis, herpes simplex, varicella, tinea infections, scabies, and allergic reactions. The presence of honey-colored crusts or intact bullae helps distinguish impetigo from these conditions.

Potential Complications

• Post-streptococcal glomerulonephritis is a serious potential complication of streptococcal impetigo, occurring in approximately 5% of cases, typically 1-2 weeks after the skin infection. It presents with hematuria, proteinuria, edema, hypertension, and decreased urine output.
• Cellulitis may develop if the infection spreads to deeper skin layers, presenting with expanding erythema, warmth, tenderness, and possibly fever. This requires prompt treatment with systemic antibiotics.
• Rare but serious complications include septicemia, osteomyelitis, septic arthritis, and scarlet fever. Children with compromised immune systems are at higher risk for these complications.

Pharmacological Management

• Topical antibiotics are first-line treatment for localized, uncomplicated impetigo. Mupirocin (Bactroban) 2% ointment applied three times daily for 5-7 days is the preferred agent. Retapamulin and fusidic acid are alternatives where available.
• Oral antibiotics are indicated for widespread impetigo (>5-10 lesions), multiple affected family members, or when topical therapy is impractical. First-line options include:
  • Cephalexin: 25-50 mg/kg/day divided QID for 7 days
  • Dicloxacillin: 25-50 mg/kg/day divided QID for 7 days
  • Clindamycin: 20-30 mg/kg/day divided TID for 7 days (for MRSA or penicillin-allergic patients)
• For MRSA-suspected infections, appropriate options include trimethoprim-sulfamethoxazole (TMP-SMX), clindamycin, or doxycycline (for children >8 years). Culture and sensitivity testing guide therapy in resistant cases.

Nursing Interventions and Patient Education

1. Perform gentle cleansing of affected areas with warm water and mild soap to remove crusts before applying topical antibiotics. Soaking with warm compresses for 15-20 minutes can help soften and remove crusts.
2. Apply prescribed topical antibiotic using clean gloves, covering the lesions completely and extending slightly beyond the affected area.
3. Administer oral antibiotics as prescribed, emphasizing the importance of completing the full course even if lesions improve.
4. Implement infection control measures including hand hygiene, keeping the child's fingernails short and clean, and using separate towels and linens for the affected child.
5. Monitor for signs of complications including spreading redness, increased pain, fever, or changes in urine appearance (hematuria).

Prevention and Health Teaching

• Educate families about proper hand hygiene techniques, including washing hands with soap and water for at least 20 seconds, especially after touching lesions and before eating.
• Advise on environmental measures including daily cleaning of toys, changing and washing linens, towels, and clothing used by the infected child in hot water, and not sharing personal items.
• Teach parents to recognize early signs of impetigo and seek prompt treatment to prevent spread. Emphasize the importance of completing the full course of antibiotics to prevent recurrence and antibiotic resistance.
• For children with recurrent impetigo, consider screening for and treating nasal carriage of S. aureus with intranasal mupirocin and chlorhexidine baths.

Impetigo vs. Other Skin Conditions

Antibiotic Selection Confusion

• Topical vs. Oral Therapy: Topical antibiotics (mupirocin) are appropriate for limited disease (fewer than 5-10 lesions), while oral antibiotics are indicated for widespread disease, systemic symptoms, or involvement of multiple family members.
• MRSA Considerations: In communities with high MRSA prevalence, empiric therapy should include MRSA coverage (TMP-SMX, clindamycin) rather than beta-lactams like cephalexin or dicloxacillin.
• Penicillin vs. Anti-staphylococcal Penicillins: Regular penicillin is effective only against streptococcal impetigo, while anti-staphylococcal penicillins (dicloxacillin, oxacillin) or first-generation cephalosporins are needed for staphylococcal impetigo.

Post-Streptococcal Glomerulonephritis vs. Rheumatic Fever

• Both are non-suppurative sequelae of streptococcal infections, but post-streptococcal glomerulonephritis (PSGN) can follow skin infections (impetigo) or throat infections, while rheumatic fever only follows streptococcal pharyngitis (not impetigo).
• PSGN typically occurs 1-2 weeks after skin infection, presenting with hematuria, proteinuria, edema, and hypertension. Rheumatic fever occurs 2-3 weeks after pharyngitis with manifestations including carditis, arthritis, chorea, erythema marginatum, and subcutaneous nodules.
• Antibiotic treatment of impetigo does not prevent PSGN but does prevent spread of nephritogenic strains to others. In contrast, timely antibiotic treatment of streptococcal pharyngitis can prevent rheumatic fever.

Clinical Judgment Tips for Impetigo Questions

• NCLEX questions on impetigo often focus on recognition of characteristic lesions, appropriate treatment selection, infection control measures, and identification of complications.
• When answering questions about impetigo treatment, remember the extent of infection guides therapy choice (topical for limited, oral for widespread), and local resistance patterns affect antibiotic selection.
• For prioritization questions, focus on preventing spread of infection, proper medication administration, and monitoring for complications like post-streptococcal glomerulonephritis.

Common Pitfalls

Quick Knowledge Check

Essential Concepts

• Pathophysiology: Impetigo is a highly contagious superficial bacterial skin infection caused primarily by S. aureus and Group A streptococci, with two main types: non-bullous (honey-colored crusts) and bullous (fluid-filled blisters).
• Assessment: Diagnosis is primarily clinical based on characteristic lesions. Risk factors include young age (2-5 years), poor hygiene, crowded conditions, warm climate, and breaks in skin integrity.
• Treatment: Topical mupirocin for limited disease; oral antibiotics (cephalexin, dicloxacillin, or clindamycin) for widespread disease or complications. Gentle removal of crusts improves treatment efficacy.
• Complications: Post-streptococcal glomerulonephritis is the most significant potential complication, occurring 1-2 weeks after infection. Cellulitis and systemic spread are rare but serious complications.
• Prevention: Hand hygiene, environmental cleaning, not sharing personal items, and prompt treatment of skin breaks help prevent impetigo. Children should be excluded from school until 24 hours after starting appropriate antibiotics.