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Fungal cells remain viable for up to 12 days in chromomycosis lesions treated by cryosurgery with liquid nitrogen

BACKGROUND: Several authors have reported on cryosurgery with liquid nitrogen (C-LN2) as an efficacious method to treat chromomycosis (CM). At first it was believed that low temperatures would destroy the infecting agents, but it was demonstrated that exposing fungal cultures to temperatures as low as -196° C did not cause fungal death. Cure mechanism has yet to be entirely understood. OBJECTIVE: To study fungal cell viability in CM lesions treated with C-LN2. METHOD: Specimens of CM lesions treated with C-LN2 were obtained by punch biopsy and seeded in Sabouraud agar. Three specimens were obtained from each of the 5 patients at 3 different occasions: 0 to 48 h after C-LN2, 5 to 7 days and 10 to 14 days. RESULTS: Colony growth was obtained with greater frequency when specimens were collected at earlier time intervals. While specimens obtained during the first 5 days after cryosurgery provided 7/8 colonies (87,5%), those obtained after the 6th post-op day were positive only in 2/7 cases (28,5%). The longest post-op time interval giving rise to a colony was 12 days. CONCLUSION: The present study suggests that tissue changes induced by C-LN2 are responsible for fungal eradication rather than low temperatures themselves. Fungal cells may be found in a viable state for up to 12 days after C-LN2.

cryosurgery; chromoblastomycosis

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