Cutaneous Diphtheria

Cutaneous diphtheria occurs when C. diphtheriae invades skin wounds or by autoinoculation from nasal/pharyngeal/laryngeal diphtheria. Acute patients usually have laryngeal or other diphtheria first; chronic cases have only skin lesions—ulcers covered by gray-white pseudomembrane.

Common Symptoms

Inflammatory cell infiltration; eschar; variola-like lesions; eczema

Causes and Pathogenesis

(1) Etiology: Corynebacterium diphtheriae is a Gram-positive coryneform rod. Main sources are patients and carriers; transmission is via droplets, contaminated hands/food to nose/mouth, but cutaneous diphtheria usually enters via broken skin, or by autoinoculation from nasal/pharyngeal/laryngeal lesions. (2) Pathogenesis: same as above.

Treatment

Drug therapy, supportive therapy

Preventive Measures

1. Control sources: isolate/treat patients until symptoms resolve and two nasopharyngeal cultures are negative; minimum 2 weeks if culture unavailable. Culture contacts and observe 7 days. Unimmunized toddlers receive purified toxoid + antitoxin. Morning checks in nurseries/schools; treat carriers with penicillin 5-7 days. Disinfect secretions (double-volume 5% cresol soap/phenol 1 h), boil utensils 15 min, or soak. 2. Cut transmission: soak patient items in 20% chloride of lime (double volume) 1 h, or 5000 ppm chlorine disinfectant 30 min. 3. Active immunization: DPT at 3, 4, 5 months, booster 1.5-2 years, purified DT at 7 and 15 years; Schick-positive children over 8 also vaccinated. Susceptible close contacts may receive 1000-2000 U diphtheria antitoxin plus toxoid for emergency protection. 4. Schick test: 0.1 ml diphtheria toxin intradermally on left forearm (1/50 MLD) and heat-inactivated control on right; negative = immunity, positive = no immunity, pseudopositive = immunity + allergy, mixed = antitoxic non-immunity + allergic reaction. 5. Passive immunization: antitoxin for weak/contacts who cannot receive toxoid; adults 1000-20000 U IM, children 1000 U, lasting 2-3 weeks; skin-test before use; give penicillin simultaneously. Serum antitoxin level ≥10 U/L is protective; incidence correlates inversely with population immunity (85-95% in some Chinese areas).

Department to Visit

It is recommended to visit the Dermatology department; an appointment can be booked on this platform before the visit.

Warm reminder: The above information is for health science reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek medical attention at a regular hospital promptly.