Hyperthermia is a promising potential adjunct to treating sporotrichosis: A refractory case of HIV sporotrichosis and in vitro experiments on Sporothrix spp.

Abstract Background Hyperthermia is a common monotherapy for sporotrichosis, but only in patients with special conditions, such as pregnancy and nursing. However, hyperthermia has not been used more widely for sporotrichosis in clinical practice. Patients/Methods An HIV‐positive adult male with lymphocutaneous sporotrichosis caused by Sporothrix globosa that did not respond to conventional itraconazole therapy lasting >2 months received adjunctive therapy with local hyperthermia. To simulate the effects of heat exposure on the growth and morphology of Sporothrix spp. in vitro, S. globosa , S. schenckii and S. brasiliensis were exposed to intermittent heat (42°C) for 1 h a day for 7 or 28 days and observed under transmission electron microscopy. Results Itraconazole combined with local hyperthermia significantly improved the lesions, and the patient was successfully cured of sporotrichosis, with no recurrence after 2 years of follow‐up. Cultures of Sporothrix spp. treated with 7 days of daily heat exposure in vitro showed obvious decreases in colony diameters, but not numbers, compared with untreated cultures ( p < .001). After 28 days of heat exposure in vitro, Sporothrix spp. were unable to thrive ( p < .001), and ultrastructural alterations, including loose cell wall structure, incomplete cell membrane, disrupted vacuoles and fragmented nuclei, were noticeable. Conclusions Our case findings and in vitro experiments on Sporothrix spp., together with a literature review of previous sporotrichosis cases, suggest that hyperthermia has a clinical role as a treatment adjunct. Large‐scale clinical trials are required to examine the utility of hyperthermia in various forms of cutaneous sporotrichosis.