What is the effect of treatment for Tinea capitis, a fungal infection of the scalp, specifically regarding its impact on the microorganism responsible for the infection?

From the Guidelines

The primary goal of treating Tinea capitis is to eradicate the causative microorganism, resulting in both clinical and mycological cure as quickly and safely as possible. Tinea capitis (scalp ringworm) is treated with oral antifungal medications, typically griseofulvin, terbinafine, itraconazole, or fluconazole, which work by directly killing the dermatophyte fungi causing the infection 1. The standard treatment involves oral griseofulvin (15-20 mg/kg/day for children < 50 kg and 1 g per day for children > 50 kg) for 6-8 weeks or terbinafine (children < 20 kg: 625 mg per day; 20-40 kg: 125 mg per day; > 40 kg: 250 mg per day) for 2-4 weeks 1. These medications penetrate the hair shaft and skin to reach the fungi, disrupting their cell membranes or inhibiting ergosterol synthesis, which leads to fungal cell death. While treatment does reduce spore shedding as a secondary effect, the primary mechanism and purpose is to kill the causative organisms.

Key Considerations

• The choice of systemic therapy should be directed by the causative dermatophyte and/or local epidemiology 1.
• Treatment must be continued for the full prescribed duration even if symptoms improve earlier to ensure complete eradication of the infection.
• Adjunctive therapy includes antifungal shampoos containing ketoconazole or selenium sulfide to reduce transmission.
• The end point of treatment is mycological rather than clinical cure; therefore repeat mycology sampling is recommended until mycological clearance is achieved 1.

Treatment Failure and Second-Line Therapy

In cases of treatment failure, initially consider lack of compliance, suboptimal absorption of drug, relative insensitivity of the organism, and reinfection 1. If there has been no initial clinical improvement, proceed to second-line therapy, which may include itraconazole, fluconazole, or voriconazole. Itraconazole is safe, effective, and has activity against both Trichophyton and Microsporum species 1.

Additional Measures

Children receiving appropriate therapy should be allowed to attend school or nursery, and index cases due to T. tonsurans warrant screening of all family members and close contacts and treatment for those positive cases 1. In asymptomatic carriers with a high spore load, systemic treatment is generally justified.

From the FDA Drug Label

Medication must be continued until the infecting organism is completely eradicated as indicated by appropriate clinical or laboratory examination. Clinical relapse will occur if the medication is not continued until the infecting organism is eradicated. The effect of treatment for Tinea capitis with griseofulvin is to eradicate the infecting organism, as indicated by clinical or laboratory examination 2.

• The treatment should be continued until the organism is completely eradicated.
• Dermatophyte infections caused by certain species of fungi, such as Microsporum and Trichophyton, can be treated with griseofulvin 2.
• Griseofulvin will not eradicate associated bacterial or yeast infections 2.

From the Research

Effect of Treatment on Tinea Capitis

The treatment for Tinea capitis, a fungal infection of the scalp, has been studied extensively. The primary goal of treatment is to eradicate the microorganism responsible for the infection.

• The standard treatment for Tinea capitis is oral griseofulvin, which has been shown to be effective in treating the infection 3, 4, 5.
• However, newer oral antifungal agents such as terbinafine, itraconazole, and fluconazole have also been found to be effective in treating Tinea capitis 3, 6, 7.
• These newer agents have the advantage of a shorter treatment duration, typically 2-4 weeks, compared to griseofulvin, which is usually taken for 6-8 weeks 6, 7.
• The efficacy of these treatments has been compared in several studies, with results showing that terbinafine, itraconazole, and fluconazole are comparable to griseofulvin in terms of efficacy and safety 5, 7.

Microorganism Response to Treatment

The microorganism responsible for Tinea capitis, typically Trichophyton tonsurans or Microsporum canis, is susceptible to the antifungal agents used to treat the infection.

• Griseofulvin has been shown to be effective against Trichophyton tonsurans and Microsporum canis, with a cure rate of 76-92% 4, 5, 7.
• Terbinafine, itraconazole, and fluconazole have also been found to be effective against these microorganisms, with cure rates ranging from 78-94% 5, 7.
• The use of adjunctive therapy, such as sporicidal shampoos, may also aid in removing adherent scales and hastening the eradication of viable spores from the scalp 6.