Current treatment of dermatophytosis

The aim of this review is to discuss topical and systemic antifungal treatment of dermatophyte infections with current antifungal drugs.     

Unusual aspects of granulomatous dermatophytosis

Described are three male patients showing bizarre manifestations of granulomatous dermatophytosis, all in the hand region. One had a small infiltrated nodular lesion near the thumb which was mistaken for a common insect bite. The second had a violaceous-yellowish plaque, also on the thumb, composed of 2–3 small subcutaneous nodules. The third case had five reddish intracutaneous nodules on the dorsum of the hand. Puncture of these nodules revealed the presence of fungal elements and culture yielded T. rubrum in all cases. Each patient was also found to have a fingernail affected by the same agent. Histologic sections in each case showed granulation tissue in the dermis and hypodermis, mainly in the vicinity of hair fragments with spores. These lesions appeared to be variants of Majocchi's granuloma trichophyticum.     

Animal dermatophytosis. Recent advances

The proportion of positive samples in relation to the number of samples examined from cases of dog and cat dermatophytosis varies considerably from one investigation to another. In dogs, it ranges between 4% and 10% and few studies show higher prevalences. On the other hand, the percentages of positive cultures cited in the reviewed literature from dogs with or without suspected dermatophytosis are quite similar. In dogs with suspected lesions of dermatophytosis, with few exceptions, Microsporum canis is the most common species isolated. Trichophyton mentagrophytes and Microsporum gypseum are less frequently isolated. In cats the prevalence of dermatophytes is usually higher than in dogs, and it is usually higher than 20%. However the frequency of positive findings is higher in cats with suspected dermatophytosis than in cats without visible lesions, with the exception of asymptomatic infected cats and transient carrier cats. Cats are accepted as the principal reservoir for M. canis. Griseofulvin is the drug of choice in canine and feline dermatophytosis.     

Immunology

It has been known for the past 85 years that mucosal responses can be stimulated by local presentation of antigen and that the gut immune system is capable of mounting both primary and secondary responses to potentially harmful antigens while avoiding the expression of damaging responses to harmless dietary proteins. How these types of responses are induced and regulated remains unclear. In the gut attention has for some time been focused on Peyer's patches (PP) due to evidence that they play a vital role in the induction of humoral and cellular responses. Moreover, it has been established that MHC class II molecules are found in the gut mucosa on a variety of cell types outside PP, namely the lamina propria (LP). Fed antigens have also been detected in the LP and studies have shown that LP cells can stimulate allogeneic mixed lymphocyte responses and are capable of presenting soluble protein antigen to naïve T cells. This article reviews the present understanding of the possible roles of PP and LP in intestinal immunity in terms of induction, regulation, surveillance of immune responses and the antigen presenting cell types involved.     

Human dermatophytosis caused by Trichophyton equinum

A case of dermatophytosis caused by Trichophyton equinum is reported. A 25-year-old man employed at a breeding center of a horse racing course was infected on the left arm in August, 1981. The lesion had a vesicle or a small pustule accompanied by severe itching. The fungal elements of the scale were identified by microscopic observation. Griseofulvin administration was found to be very effective for treating this infection. In a mycological examination, T. equinum was isolated mainly on cycloheximide-chloramphenicol Sabouraud's dextrose agar and chloramphenicol potato dextrose agar. Equine dermatophytosis was quite prevalent at this race course, so that this area as well as equipment used for the maintenance and care of the horse was very likely to be the source of the patient's infection.