bubble_chart Overview

Impetigo Contagiosa, also known as pustular sore or contagious pustular dermatitis, commonly referred to as yellow-water sore (impetigo), is one of the most common suppurative skin diseases caused by pyogenic cocci. It is primarily characterized by superficial pustules and crusts, spreads rapidly upon contact, frequently occurs during summer and autumn on exposed areas, and is prone to outbreaks among groups of children.

bubble_chart Etiology

It is mainly caused by coagulase-positive Staphylococcus aureus infection, mostly by group II type 71 strains, followed by beta-hemolytic streptococcus. It can also be a mixed infection of both bacteria, and rarely caused by other bacteria such as Staphylococcus epidermidis, Bacillus subtilis, etc.

Most patients are children and infants. Due to anatomical and physiological weaknesses such as delicate skin, poor local resistance, susceptibility to minor trauma, and easy skin contamination, children are prone to pyogenic bacterial infections. Especially in newborns, the skin is thin and tender, secretory functions are not fully developed, immunity is low (IgG levels are below normal), and neurological functions are immature, making them susceptible to systemic spread after infection, leading to outbreaks in groups. In adults, when suffering from certain diseases that reduce the body's resistance, general weakness, or cutaneous pruritic skin diseases that lower the resistance of a specific skin area, as well as various irritations and skin trauma, pyogenic cocci can easily take advantage and cause infection.

In families or nurseries, close contact among children makes it easy for epidemics to occur. It can also spread indirectly through contaminated towels, daily necessities, toys, clothing, etc.

bubble_chart Pathological Changes

The pathological changes show that the pustules are located between the stratum corneum and the granular layer, containing fibrin and a large number of neutrophils. Pyogenic cocci are easily found within the pustules, especially at the edges. The epidermis exhibits significant intercellular edema (spongiosis) and abundant neutrophils. The dermis shows interstitial edema, vascular dilation, and infiltration of neutrophils and lymphocytes.

bubble_chart Clinical Manifestations

Pestilence Impetigo is prevalent in summer and autumn, mostly occurring in children. It is highly pestilent and easily spreads among family members, commonly seen in exposed areas. Due to different infecting cocci, the clinical manifestations vary. Infections caused by Staphylococcus aureus mainly present as bullous impetigo. Initially, there are scattered bright red papules or blisters, which rapidly expand to the size of a broad bean or larger. The fluid inside the blisters, initially clear, becomes turbid and turns into pus, forming pustules surrounded by erythema. Sometimes, the upper part of the pustule contains clear fluid, while the lower part appears crescent-shaped due to the deposition of turbid yellow pus at the base, forming a characteristic feature of the disease. The blister walls are very thin, loose, and prone to rupture, leading to erosions that dry into yellow crusts. Occasionally, pus under the crust may spread to the surrounding areas, forming new pustules around the original lesions, sometimes arranged in rings or chains, known as annular impetigo. It commonly occurs on exposed areas such as the face and limbs, accompanied by cutaneous pruritus, and generally lacks systemic symptoms.

Infections caused by hemolytic streptococci or mixed infections with Staphylococcus aureus mainly present as crusted impetigo. It often occurs on exposed areas such as the face, corners of the mouth, lips, nostrils, ears, and limbs. Thin-walled blisters appear on an erythematous base and quickly develop into pustules surrounded by erythema. After the pustules rupture, the pus dries to form thick, honey-yellow crusts. New lesions continuously appear around the existing ones, accompanied by cutaneous pruritus, and often spread to other parts of the body due to scratching. In a few cases, the nasal cavity, oral cavity, and tongue mucosa may also be affected. Severe cases may be accompanied by lymphadenitis, furunculosis, erysipelas, or lymphangitis. Systemic symptoms such as fever and fear of cold may occur, and acute nephritis may be induced. In rare cases, severely debilitated children or newborns may develop sepsis, leading to death.

bubble_chart Diagnosis

Based on the clinical characteristics of the lesion, the season of onset, age, location, primary lesion being pustules with surrounding erythema, clear fluid on top and turbid fluid at the bottom of the pustules, absence of scarring after healing, high contagiousness, laboratory findings showing increased total white blood cell count and neutrophils, and bacterial culture of pus revealing Staphylococcus aureus and Streptococcus, the diagnosis is generally not difficult.

bubble_chart Treatment Measures

Patients should pay attention to general health, maintain skin hygiene, keep clothing clean, bathe frequently in summer, and especially ensure frequent hand washing, trimming nails short, and avoiding scratching the affected areas to prevent widespread skin damage. Isolate patients to prevent pestilence.

1. Systemic Therapy: Generally, patients do not require internal medication; maintaining cleanliness and using only antibacterial topical medications is sufficient. However, for those with severe symptoms, extensive skin lesions, accompanied by fever and purulent bacterial infections, or those who have not responded to long-term topical treatment, sulfonamides and antibiotic preparations may be administered. For severe cases, it is best to conduct pus culture and drug sensitivity tests to select the most effective antibiotics. Neonatal impetigo should be treated as a severe infection, using cefazolin V, or alternatively, erythromycin, penicillin, and compound formula sulfamethoxazole, among others.

2. Local Therapy: Local treatment should adhere to the principles of sterilization, anti-inflammation, itch relief, drying, astringency, and preventing further spread. Before applying medication, use a sterilized needle to puncture blisters or pustules and absorb the fluid with sterile cotton balls, taking care not to spill the fluid onto healthy skin. Clean the affected area with 0.1% rivanol, 3% hydrogen peroxide, 1/2000 Coptis Rhizome solution, or 1/5000 potassium permanganate solution to remove pus scabs. For eliminating dampness and erosion, a 1/5000 potassium permanganate solution wet compress may also be used. Then, apply sulfur calamine lotion, 1% Chinese Gentian violet solution, 0.5% neomycin solution, or alternatively, 10% ichthammol ointment, Bactroban ointment, as well as erythromycin or chloramphenicol ointment, among others. Apply medication twice daily.

bubble_chart Differentiation

Sometimes it needs to be differentiated from the following diseases:

1. Ecthyma. After ecthyma ruptures, it forms an ulcer surface and leaves shallow scars after healing. It mostly occurs on the lower legs and is common in adults.

2. Pemphigus. Pemphigus is primarily characterized by blisters, with pustules resulting from secondary infections. Nikolsky's sign is positive, and it mainly occurs in adults. A necessary seasonal disease pathological examination can help differentiate.

3. Infected eczema. Infected eczema has a history of eczema, with polymorphic lesions such as erythema and papules visible on the skin, along with redness, swelling, and inflammatory manifestations. Pustules and crusts are secondary lesions.

4. Chickenpox. It is more common in winter and spring, often accompanied by systemic symptoms such as fever, discomfort, and headache before and in the early stages of the disease. The rash is mainly small blisters, mostly centripetally distributed, with various lesions such as erythema, papules, and crusts visible simultaneously. The oral mucosa is often affected.

5. Papular urticaria. It is characterized by papules or blisters appearing on wheal-like erythema, occurring on the trunk and limbs in batches, recurring repeatedly, and causing intense itching.

6. Neonatal impetigo. Neonatal impetigo occurs in newborns, with large pustules and severe systemic symptoms.