Dermatophytes are fungi that cause
infections of keratinized tissues. We have recently demonstrated the susceptibility of the dermatophyte Trichophyton rubrum to photodynamic treatment (
PDT) with 5,10,15-Tris(4-methylpyridinium)-20-phenyl-[21H,23H]-
porphine trichloride (
Sylsens B) in 5 mm
citric acid/
sodium citrate buffer (pH 5.2, formulation I). In this work, we examined the penetration of
Sylsens B in healthy and with T. rubrum infected skin and we investigated the susceptibility of T. rubrum to
PDT using formulation I and UVA-1 radiation (340-550 nm). Skin penetration studies were performed with formulations I and II (
Sylsens B in PBS, pH 7.4) applied on dermatomed skin, human stratum corneum (SC), disrupted SC by T. rubrum growth and SC pretreated with a
detergent. No penetration was observed in healthy skin. Disruption of SC by preceding fungal growth caused
Sylsens B penetration at pH 7.4, but not at pH 5.2. However, chemically damaged SC allowed
Sylsens B to penetrate also at pH 5.2. UVA-1
PDT was applied ex vivo during two fungal growth stages of two T. rubrum strains (CBS 304.60 and a clinical isolate). Both strains could be killed by UVA-1 alone (40 J/cm(2)). Combined with formulation I (1 and 10 microm
Sylsens B for, respectively, CBS 304.60 and the clinical isolate), only 18 J/cm(2) UVA-1 was required for fungal kill. Therefore,
PDT with 10 microm
Sylsens B (formulation I) and 18 J/cm(2) UVA-1 could be considered as effective and safe. This offers the possibility to perform clinical studies in future.