Cutaneous Infection Caused by Mycobacterium marinum in Thailand: A 14-Year Retrospective Cohort Analysis of Clinical Characteristics, Complication Risks, and Treatment Efficacy

Background: Mycobacterium marinum (M. marinum) is an atypical mycobacterial strain causing skin infections. Limited research has evaluated its clinical presentation and treatment outcomes. This retrospective cohort study examined the characteristics and treatment outcomes of cutaneous M. marinum infection at a tertiary care hospital in Thailand. Methods: This study reviewed patients diagnosed with M. marinum infection between 2005 and 2019. Patients were followed for 1 year after being cured. Factors associated with complications were analyzed using binary logistic regression. Results: The cohort comprised 20 males and 7 females (mean age = 45.5 ± 15.4 years). A history of fish or water exposure was reported in 59.3% of the patients. Most patients developed hand lesions (81.5%), with plaques and nodules as the primary morphologies (51.9% and 29.6%, respectively). A sporotrichoid pattern was observed in one-third of the patients (29.6%). Tenosynovitis occurred in 22.2% of patients, with a female preponderance (adjusted p = 0.028), advanced age (p = 0.032), and prior steroid injections at the lesion site (p = 0.007) being common factors. The mean duration of cure was 5.6 ± 3.1 months, with immunosuppression significantly associated with a longer duration (p = 0.047). Doxycycline and clarithromycin were the most effective antibiotics. Surgical debridement combined with oral antibiotics successfully treated all tenosynovitis patients, with no recurrence during the 1-year follow-up. Conclusions: Aquagenic contact history aids in diagnosing M. marinum infection. Females, patients with a history of intralesional corticosteroid injection, and older patients are predisposed to tenosynovitis. Treatment duration is prolonged in immunocompromised patients.