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Mycopathologia 158: 173180, 2004.
2004 Kluwer Academic Publishers. Printed in the Netherlands. 173Trichoderma spp. antagonism to the dermatophyte Trichophyton
rubrum: implications in treatment of onychomycosisC. Omero, Y. Dror & A. FreemanDepartment of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel Aviv Univresity,
Tel Aviv 69978, IsraelReceived 27 October 2003; accepted in revised form 6 May 2004AbstractOnychomycosis the dermatophytic invasion of the nail is dicult to eradicate with drug treatment. The
hyphae of the main invading pathogen, Trichophyton rubrum, are often interwoven with the nail plate,
preventing eective anti-mycotic agents from reaching its growing tips. An alternative approach to treat
onychomycosis may possibly be the application of a biological control agent against the pathogen. In
analogy with the success of biocontrol of phytopathogenic fungi, we screened a series of commercially
available Trichoderma strains for potential antagonism between Trichoderma and Trichophyton spp. A wide
spectrum of antagonism capacity, ranging from eective overgrowth to no interaction was found, with
Trichoderma virens NRRL 26672 being the most eective against the Trichophyton strains tested e.g.T. rubrum NCPF118. Furthermore, T. virens NRRL 26672 grown with T. rubrum NCPF118 hyphae as a
carbon source, exhibited enhanced induced secretion of active extracellular chitinases and b-glucosidases,
aecting lysis and sporulation on T. rubrum NCPF118 hyphae. Growth of Trichod. virens NRRL 26672 in
poor medium also resulted in secretion of antibiotics active in arresting the growth of T. rubrum NCPF118
inoculum. Our ndings may open new directions for the treatment of onychomycosis, either in combination
with known medications or as a new natural route.Key words: antagonism, trichophyton, trichoderma, onychomycosisIntroductionThe major cause of onychomycosis fungal nail
infection is the dermatophytic invasion of the nail
plate by members of the genera Trichophyton,
Microsporum,and Epidermophyton. The species
that most often cause onychomycosis are Trichophyton rubrum, Trichophyton mentagrophytes andE. occosum. Dermatophytosis of the nails are
particularly dicult to eradicate with drug treatments mainly due to the protective nail plate,
sequestration of the pathogens between the nail bed
and plate and the slow growth of the nail [13]. The
most frequently employed anti-mycotic agents used
to treat onychomycosis are based on allylamine and
azole derivatives, orally administered for long
periods of time (several months), with potentialharmful side eects on liver functions [1]. Whenever
applied persistantly, these treatments are usually