4. Discussion
In this experiment the growth inhibition, ergosterol content and keratinase enzyme activity (total and specific evaluation methods) in Trichophyton rubrum were studied by cold atmospheric plasma (CAP) device. Since it was considered very important that dermatophytes, triggered by fungus, especially Trichophyton rubrum, as one of the main causes of relatively high worldwide occurrence of superficial infections in human and animals would require a reliable method for their treatments. Recently, scientists have studied plasma antifungal properties extensively. Therefore, a series of attempts have been made on the development and performance of various atmospheric pressure plasma techniques, such as plasma jets, dielectric barrier discharges, and plasma needles to combat fungi causing diseases. In 2013, Heinlin et al. (2013) used SMD plasma containing ambient air without any active flow on single colony of Trichophyton rubrum and Microsporum canis, in one application and daily treatment with single CAP for 5, 8 and 10 min showing less fungal growth inhibition as compared to a daily CAP treatment only [19]. In another study, Daeschlein et al. (2011) showed that with atmospheric pressure plasma jet (APPJ), using argon gas flowing on colonies of Trichophyton rubrum, T. interdigitale, and M. canis and the yeast Candida albicans, in vitro could kill more than 90% of the microorganisms during 30 s [39]. Less than two years ago, Ali et al. (2014) using FE-DBD plasma, with argon as a working gas, investigated its antifungal activity on Trichophyton mentagrophytes and T. rubrum in saline and in an infected skin model which showed that a significant inhibition occurred by both strains in conidia and hyphal growth, in the infected skin mimicking model. They also produced a time-dependent correlation between the intracellular reactive species (ROS) and the fungal cell viabilities after plasma treatment [40]. Specially, many research reports have been published on plasma effect on Candida species. Sun et al. (2011) used cold plasma microjet that contained helium and oxygen 2% on Candida albicans, Candida krusei, and Candida glabrata with fluconazole resistance in air and in water. Their result showed that 90% inactivation was achieved in 10 min in air and 1 min in water [16]. In 2013, Keidar et al. used cold plasma, working with helium gas, in cancer therapy. They found that the cold plasma application selectively destroyed cancer cells in-vitro without damaging the normal cells and reduced tumor size in-vivo considerably [33]. “Plasma functions selectively”, implied that it was able to select between healthy and unhealthy cells in our body; a characteristics which can help treatments of many diseases.
