July 25, 2014

Treatments for frog fungus

The fungicide amphotericin B may be a useful treatment for a frog fungus that is killing amphibians worldwide.


Chytridiomycosis – an invasive skin disease caused by the fungal pathogen B. dendrobatidis – is killing amphibians worldwide. Current treatment of the fungus (for amphibians in captivity) uses itraconazole, but toxicity and emerging resistance emphasize the need for other antifungals.

Louise Rollins-Smith, Ph.D., and colleagues have now evaluated chloramphenicol and amphotericin B against B. dendrobatidis in vitro and in vivo. They found that both chloramphenicol and amphotericin B reduced B. dendrobatidis infection in naturally infected southern leopard frogs, but neither drug completely cleared the fungus. They also evaluated innate skin defenses in the frogs – the production of antimicrobial peptides and the existence of protective skin bacteria. None of the drugs inhibited antimicrobial peptide synthesis, but chloramphenicol inhibited the growth of skin bacteria, suggesting that it may alter the naturally protective skin microbiome.

The findings, reported in the July issue of Applied and Environmental Microbiology, suggest that amphotericin B might be a useful addition to itraconazole for treating chytridiomycosis.

This work was supported by grants from the National Science Foundation (IOS-0619536, IOS-0843207, IOS-1121758).

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