Efficacious Treatment of Non-Dermatophyte Mould Onychomycosis with Topical Amphotericin B

Authors’ Interview:

Massimo C. R. Lurati MD
Florence Baudraz-Rosselet MD
Prof. Michel Monod PhD

Private practice and Department of Dermatology
Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland

What are the main findings of the study?

Dermatophytes are the main cause of onychomycosis, but a significant percentage of cases are due to various non-dermatophyte moulds especially when considering abnormal nails.

Fusarium spp. and other moulds are mostly insensitive to standard onychomycosis treatment with topical agents as well as with oral terbinafine and itraconazole (see reference 2 below).

We found that specially formulated topical amphotericin B was an efficacious, safe, cheap and easy to apply treatment for onychomycosis where non-dermatophyte moulds such as Fusarium sp., Acremonium sp. or Aspergillus sp. were the confirmed infectious agent.

Were any of the findings unexpected?

We were surprised at the speed with which healthy fungal filaments became dystrophic on direct nail smears after initiation of treatment. This is in accord with the known fungicidal mechanism of action of amphotericin B (this in contrast to the fungistatic azoles and allyamines currently in use).

What should clinicians and patients take away from this study?

Fusarium spp. and other non-dermatophyte moulds are especially difficult if not impossible to cure utilising standard treatment regimens with terbinafine and itraconazole.

It is now possible to reliably cure non-dermatophyte mould onychomycosis with topical amphotericin B. Importantly, no local or systemic side-effects are associated with this treatment.

What recommendations do you have for future research as a result of your study?

One certainly needs to further confirm the efficacy of our treatment by means of larger studies but we believe the most pressing need is for the development and widespread implementation of a rapid and practical molecular in situ fungal identification method that can be used to diagnose the etiological agent of onychomycosis before initiating treatment.

How do you identify a non-dermatophyte mould as the infectious agent in onychomycosis?

There is a suspicion of non-dermatophyte mould onychomycosis when standard empirically prescribed topical and systemic onychomycosis treatments fail.
Nowadays, different fast and reliable PCR methods of mould identification in nails are available (see references 3-5 below) and it should be standard procedure to obtain culture or PCR identification of an eventual nail pathogen before initiating any treatment. This is logical from a pharmacoeconomic point of view and a medico-legal one, the latter in case of serious treatment

References

1. Lurati M, Baudraz-Rosselet F, Vernez M, Spring P, Bontems O, Fratti M, Monod M. Efficacious Treatment of Non-Dermatophyte Mould Onychomycosis with Topical Amphotericin B. Dermatology. 2012 Jan 10
2. Baudraz-Rosselet F, Ruffieux C, Lurati M, Bontems O, Monod M. Onychomycosis insensitive to systemic terbinafine and azole treatments reveals non-dermatophyte moulds as infectious agents. Dermatology. 2010;220(2):164-8.
3. Verrier J, Pronina M, Peter C, Bontems O, Fratti M, Salamin K, Schürch S, Gindro K, Wolfender JL, Harshman K, Monod M.Identification of infectious agents in onychomycoses by Polymerase Chain Reaction-Terminal Restriction Fragment Length Polymorphism. J Clin Microbiol. 2011 Dec 14. [Epub ahead of print]
4. Bontems O, Hauser PM, Monod M. Evaluation of a polymerase chain reaction-restriction fragment length polymorphism assay for dermatophyte and nondermatophyte identification in onychomycosis. Br J Dermatol. 2009;161(4):791-6.
5. Monod M, Bontems O, Zaugg C, Léchenne B, Fratti M, Panizzon R. Fast and reliable PCR/sequencing/RFLP assay for identification of fungi in onychomycoses. J Med Microbiol. 2006;55(Pt 9):1211-6.