Application of post-discharge region of atmospheric pressure argon and air plasma jet in the contamination control of Candida albicans biofilms

Abstract

Introduction: Candida species are responsible for about 80% of hospital fungal infections. Non-thermal plasmas operated at atmospheric pressure are increasingly used as an alternative to existing antimicrobial strategy. This work investigates the action of post-discharge region of a non-thermal atmospheric plasma jet, generated by a gliding arc reactor, on biofilms of standard strain of Candida albicans grown on polyurethane substrate. Methods: Samples were divided into three groups: (i) non-treated; (ii) treated with argon plasma, and (iii) treated with argon plus air plasma. Subsequently to plasma treatment, counting of colony-forming units (CFU/ml) and cell viability tests were performed. In addition, the surface morphology of the samples was evaluated by scanning electron microscopy (SEM) and optical profilometry (OP). Results: Reduction in CFU/ml of 85% and 88.1% were observed in groups ii and iii, respectively. Cell viability after treatment also showed reduction of 33% in group ii and 8% in group iii, in comparison with group i (100%). The SEM images allow observation of the effect of plasma chemistry on biofilm structure, and OP images showed a reduction of its surface roughness, which suggests a possible loss of biofilm mass. Conclusion: The treatment in post-discharge region and the chemistries of plasma jet tested in this work were effective in controlling Candida albicans biofilm contamination. Finally, it was evidenced that argon plus air plasma was the most efficient to reduce cell viability.

Effect of Storage Temperature on pH and Conductivity of Reverse Osmosis Water Treated with Atmospheric Plasma

“…The treatment group varied in plasma exposure time of ~ 10 (T10), 20 (T20), and 30 (T30) min. We used a gliding arc type of reactor, previously described in studies by Doria et al 11 and Simomura et al 12 For treatments, we used gas composed of a mixture of compressed air (using the medical odontological compressor MSV 6/30) (Schulz SA; São Paulo, Brazil) that we treatment was performed in the discharge region. Figure 1 illustrates the treatment scheme.…”

Comparative Study of Candida albicans Inactivation by Nonthermal Plasma on Stainless Steel with and without Diamond-like Carbon Film

“…The same C. albicans on DLC showed a reduction of 96.4% in the first 5 min, with the values for other times ranging from 95.6 (10 min) to 99.6% (20 min). These results were in agreement with the findings of Simomura et al 25 and Doria et al, 61 where the reductions of fungal counts on silicone and polyurethane substrates, respectively, were correlated with longer plasma exposure times. Compared with plasma treatment, photodynamic antimicrobial chemotherapy described by da Silva et al, 8 where the surface was exposed to toluidine blue and a light-emitting diode (LED) for 5 min, achieved elimination of only 20% of C. krusei microorganisms.…”

“…The samples were then placed in sterile Petri dishes and dried in an oven at 35 °C before the tests employing the plasma. 61 modified concerning the amount of Sabouraud broth used during biofilm growth for different strains of C. albicans ATCC 90028 and strains originating from urine and tracheal secretion (codes 1251 and 1311, respectively). The culture was performed under static conditions without agitation for 48 h. Time zero was considered as the control (without plasma application).…”

Potential applications of nonthermal plasmas against biofilm-associated micro-organisms in vitro

“…Recently, Doria et al . () investigated the effect of the postdischarge region of a nonthermal atmospheric plasma jet, generated with mixtures of argon and air, on standard strain biofilms of C. albicans grown on polyurethane substrate. Reduction in CFU per ml of 85 and 88·1% were observed in groups treated with argon plasma and treated with argon plus air plasma respectively.…”