Inactivation of Candida albicans, Staphylococcus aureus and multidrug-resistant Escherichia coli with dielectric barrier discharged cold atmospheric plasma: a comparative study with antimicrobial drugs.

Abstract

Introduction. Cold atmospheric plasma (CAP) has emerged as a promising technology for neutralizing microbes, including multidrug-resistant strains. This study investigates CAP's potential as an alternative to traditional antimicrobial drugs for microbial inactivation.Hypothesis/Gap Statement. In the era of increasing antimicrobial resistance, there is a persistent need for alternative antimicrobial strategies. CAP exerts its effects by generating reactive oxygen and nitrogen species (RONS), but its comparative efficacy against antimicrobial drugs requires further exploration.Aim. To evaluate the antimicrobial efficacy of CAP in inactivating multidrug-resistant Escherichia coli (ATCC BAA-2469), Staphylococcus aureus (MTCC 96) and Candida albicans (MTCC 227) and to compare its effectiveness with standard antimicrobial drugs.Methodology. CAP, produced by an indigenously developed dielectric barrier discharge (DBD) setup comprising a quartz-glass-covered high-voltage electrode and a grounded stainless steel mesh electrode, was used to treat three pathogenic samples with varying treatment times (0-60 s). The zone of inhibition (ZoI; zone where microbes cannot grow) induced by CAP was compared with the ZoI of selected antimicrobial drugs (5-300 mcg). Scanning electron microscopy (SEM) analysed morphological changes, while optical emission spectroscopy (OES) detected RONS generated during treatment. Growth curve analysis assessed CAP's impact on microbial growth, and statistical analysis compared CAP-induced ZoI with drug-induced ZoI.Results. CAP treatment produced substantial ZoI against E. coli, S. aureus and C. albicans, with the largest ZoI (1194±35.35 mm²) in C. albicans after 60 s. DBD-CAP showed equivalent or superior efficacy compared with selected antimicrobial drugs based on ZoI comparisons. SEM revealed extensive cellular damage in all three pathogens, with visible morphological disruption within 60 s. Growth curve analysis showed a significant delay in microbial proliferation with increasing CAP exposure, effectively inhibiting growth over 24 h. OES confirmed the presence of RONS-related molecular bands [N₂(C-B), N₂ ⁺(B-X) and OH(A-X)] and atomic O lines in the CAP.Conclusion. CAP treatment exhibits equivalent or superior antimicrobial activity compared to selected antimicrobial drugs. CAP treatment exerts effects by inactivating pathogens, disintegrating cellular morphology and delaying microbial growth. These findings highlight CAP as a promising alternative to prolonged treatments, addressing antimicrobial resistance and advancing clinical strategies.