impetigo Flashcards
What is impetigo?
Impetigo is a common, superficial, highly contagious bacterial skin infection characterized by pustules and honey-colored crusted erosions.
Which layers of the skin does impetigo affect?
Impetigo affects the superficial layers of the epidermis.
What are the common pathogens that cause impetigo?
The common pathogens are Staphylococcus aureus and Streptococcus pyogenes (Group A beta-hemolytic streptococci).
What are the two types of impetigo?
Non-bullous (school sores) and bullous impetigo.
What is ecthyma?
Ecthyma is a deep form of impetigo that causes deeper erosions of the skin into the dermis.
What is impetiginisation?
Impetiginisation refers to the secondary infection of wounds or other skin lesions with the same pathogens that cause impetigo.
Who is most commonly affected by impetigo?
Impetigo is most common in young children but can occur at any age.
What skin conditions can predispose someone to impetigo?
Atopic dermatitis, contact dermatitis, scabies, and chickenpox.
What bacteria can cause non-bullous impetigo?
Non-bullous impetigo can be caused by Staphylococcus aureus, Streptococcus pyogenes, or both bacteria together.
How does non-bullous impetigo typically occur?
It occurs when a disruption in skin integrity allows bacteria to invade through the interrupted surface.
Which bacteria causes bullous impetigo, and what toxins does it produce?
Bullous impetigo is caused by Staphylococcus aureus, which produces exfoliative toxins (exfoliatins A and B).
What do exfoliative toxins target in bullous impetigo?
They target intracellular adhesion molecules (desmoglein-1) in the epidermal granular layer.
Where is non-bullous impetigo most commonly found?
Non-bullous impetigo is most commonly found on the face or extremities, but it can occur on any part of the body.
How does bullous impetigo present?
It presents as quickly appearing superficial, small or large thin-roofed bullae that tend to rupture and ooze yellow fluid, leaving a scaly rim (collarette).
How does non-bullous impetigo initially present?
It begins with a single erythematous macule that evolves into a pustule or vesicle.
What are “kissing lesions” in non-bullous impetigo?
“Kissing lesions” occur where two skin surfaces are in contact and lesions spread through autoinoculation.
Where is bullous impetigo usually found?
Bullous impetigo is usually found on the face, trunk, extremities, buttocks, and perineal regions.
What is scarlet fever, and how is it related to impetigo?
Scarlet fever is an illness caused by toxins from Streptococcus pyogenes, which can complicate impetigo.
What topical treatments can be used for impetigo?
Dress or bathe affected areas with potassium permanganate, gentian violet (GV) paint, betadine solution, or saline, or wash with betadine shampoo.
How can the spread of impetigo to others be prevented?
Do not share towels or ointments, and change clothes, towels, and sheets frequently.
What should be avoided in the topical care of impetigo, and what should be used instead?
Avoid using Vaseline; use aqueous cream instead.
What oral antibiotic is recommended for severe cases of impetigo in adults?
Cloxacillin 250-500 mg four times daily for 7-10 days
What is the recommended dosage of cloxacillin for children with severe impetigo?
50-100 mg/kg/24 hours, divided into four doses for 7-10 days.
What is an alternative antibiotic for severe impetigo, and what is the adult dosage?
Erythromycin 250-500 mg four times daily for 7-10 days.
What is the recommended dosage of erythromycin for children with severe impetigo?
25-50 mg/kg/24 hours, divided into four doses for 7-10 days
