Clinical presentation, etiology, and treatment outcomes of mycetoma: A 25-year retrospective study in Southern Thailand

TL;DR

A 25-year study in southern Thailand found that mycetoma is caused by diverse fungi and bacteria, with modest treatment success and frequent complications.

Contribution

The study provides the first detailed 25-year analysis of mycetoma in southern Thailand, revealing distinct regional epidemiology and treatment challenges.

Findings

Eumycetoma was more common than actinomycetoma, caused by diverse fungi like Exophiala jeanselmei and Scedosporium.

Cure rates were modest at 54%, with 10% recurrence and 3% requiring amputation despite combined medical and surgical treatment.

Histopathology was more reliable than culture for diagnosing mycetoma, especially for actinomycetoma.

Abstract

Mycetoma is a chronic subcutaneous infection caused by fungi (eumycetoma) or filamentous bacteria (actinomycetoma). Although recently recognized by the World Health Organization as a neglected tropical disease, data from Southeast Asia are scarce. Previous reports from Thailand were limited and outdated.

We conducted a 25-year retrospective study (2000–2025) at a tertiary referral hospital in southern Thailand. Patients were identified from hospital records and confirmed by histopathology and/or culture. Fifty patients met inclusion criteria: 31 (62%) had eumycetoma and 19 (38%) had actinomycetoma. The median age was 50 years (IQR 41.8-58.0), and 62% were male. The foot was the most common site (80%), with bone involvement in 28%. Sinus tracts occurred in 43%, but visible grains were recorded in only 12%. Histopathology (performed in 86%) reliably distinguished fungal from bacterial etiologies, whereas culture yield was low, especially for actinomycetoma (27%). Among eumycetoma, identified pathogens included dematiaceous fungi such as Exophiala jeanselmei and hyaline molds such as Scedosporium and Fusarium. Among the few culture-positive actinomycetoma cases, all isolates were Nocardia spp. Itraconazole was the main antifungal, whereas trimethoprim-sulfamethoxazole was used for actinomycetoma. Surgery was performed in 66% of patients. At a median follow-up of 21 months (IQR 7.5–46.0), 54% achieved cure, 24% improved, 10% recurrence, and 3% required amputation.

Mycetoma in southern Thailand is uncommon but clinically significant. Unlike classical endemic regions, eumycetoma predominated and was caused by diverse fungi rather than Madurella mycetomatis. Despite combined medical and surgical therapy, cure rates were modest and complications frequent. These findings highlight regional differences in epidemiology and underscore the need for strengthened diagnostics, access to effective therapy, and region-specific neglected tropical disease strategies in Southeast Asia.

Mycetoma is a neglected tropical disease that causes chronic swelling, sinus tract formation, and disability. It is well known in the “mycetoma belt” of Africa, India, and Latin America, but little is known about its patterns in Southeast Asia. We reviewed 25 years of cases at a large referral hospital in southern Thailand. Fifty patients were identified, most of them middle-aged farmers. The disease usually affected the foot and sometimes spread to the bone. Unlike classical endemic regions where Madurella mycetomatis predominates, we found eumycetoma caused mainly by a variety of fungi, including dematiaceous molds such as Exophiala jeanselmei, as well as hyaline molds like Scedosporium and Fusarium. For actinomycetoma, cultures were often negative, but when positive they consistently grew Nocardia species. Treatment required long courses of antifungal or antibacterial drugs, often combined with surgery. Despite intensive management, many patients experienced relapse or long-term complications, and some required amputation. Our findings demonstrate that mycetoma in Thailand has distinctive causes and clinical features, differing from global trends. Recognizing these differences is important for improving diagnosis, treatment, and prevention strategies tailored to Southeast Asia.

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