Effect of ozone gas on cultures of Candida albicans and Aspergillus fumigatus: evaluation of two ozonation devices.

INTRODUCTION: Candida albicans and Aspergillus fumigatus are two important agents of Healthcare-associated infections. This study aimed to evaluate the antifungal activity of ozone (O3) gas produced by two commercial devices against cultures of these two species. METHODOLOGY: Sterile plastic plates were inoculated with C. albicans and A. fumigatus and placed on a countertop at three distances (30 cm, 1 m, and 2 m) and three positions in relation to the wall (near, middle, and away), considering the source of O3. Plates were exposed to O3 for one hour and incubated. After incubation, the counting of colony-forming units was performed. As a control, an inoculated plate was incubated, without being exposed to O3. Tests were carried out with two different devices (namely, Mod.I and Mod.II), with the air conditioner on and off, in triplicate. RESULTS: Both devices showed antifungal activity. Mod. I presented better results, due to a higher flow rate. The best activity was on plates at 30 cm, middle position. Contrarily, on plates at 2m, near the wall, the inhibition activity was lower. The best results were obtained with the air conditioner off. Candida albicans was more sensitive to O3 than A. fumigatus. CONCLUSIONS: This method of decontamination by O3 gas shows potential due to its fast and easy execution. The establishment of new protocols for hygiene and hospital disinfection using this approach should be considered, which may reduce environmental contamination by fungi and, consequently, the burden of fungal infections.

Ação antimicrobiana do gás ozônio em superfícies e na aeromicrobiota / Acción antimicrobiana del gas ozono en superfi cies y en la microbiota del aire / Antimicrobial action of ozone gas on surfaces and in the air

Resumo Objetivo: Avaliar a ação antimicrobiano do gás ozônio (O3) em superfícies e ar ambiente climatizado artificialmente. Métodos: Estudo experimental/laboratorial e transversal realizado em dez salas de um laboratório de pesquisa em microbiologia médica, com risco de segurança biológica classe 2. As superfícies demarcadas do chão, parede e bancada foram avaliadas, quanto à presença ou ausência de micro-organismos, a partir de coletas feitas com swab umedecido em água destilada estéril, antes e após a exposição do gás O3 gerado por dois equipamentos distintos. Após este procedimento, o swab foi inoculado na superfície do meio de cultura Brain Heart Infusion Agar DIFCO® (BHI), seguindo-se a incubação a 35ºC por 24 horas. Para a análise microbiológica do ar, uma placa com BHI foi exposta aberta por uma hora, antes e após o tratamento do gás O3, sendo incubadas segundo os mesmos critérios. Resultados: A atividade antimicrobiana do gás O3 gerado por ambos os equipamentos foi constatada para todas as áreas investigadas, com registros de redução do número de Unidades Formadoras de Colônias. O potencial de inibição antimicrobiana dos aparelhos se manteve próximo para os critérios de análise adotados, com destaque para as áreas de chão e bancada. Considerando-se todas as salas e percentuais de inibição microbiana, frente aos dois equipamentos, os resultados foram: chão (100%), bancada (90%), parede (50%) e ar, 70%. Conclusão: Os equipamentos geradores de gás O3 apresentaram potencial antimicrobiano para medida de controle de microrganismos presentes em superfícies e ar ambiente climatizado artificialmente, sendo um sanitizante factível para utilização.

Resumen Objetivo: Evaluar la acción antimicrobiana del gas ozono (O3) en superficies y en el aire interior climatizado artificialmente. Métodos: Estudio experimental/de laboratorio y transversal realizado en diez salas de un laboratorio de investigación en microbiología médica, con riesgo de seguridad biológica clase 2. Se evaluaron las superficies delimitadas en el piso, pared y mesa en cuanto a la presencia o ausencia de microorganismos, a partir de muestras recolectadas con hisopo humedecido en agua destilada estéril, antes y después de la exposición del gas O3 generado por dos máquinas distintas. Luego de este procedimiento, el hisopo fue inoculado en la superficie del medio de cultivo Brain Heart Infusion Agar DIFCO® (BHI), y después incubado a 35 °C por 24 horas. Para el análisis microbiológico del aire, se expuso una placa con BHI abierta durante una hora, antes y después del tratamiento del gas O3, y luego se incubó con los mismos criterios. Resultados: Se constató la actividad antimicrobiana del gas O3 generado por ambas máquinas en todas las áreas investigadas, y se registró una reducción del número de unidades formadoras de colonias. El potencial de inhibición antimicrobiana de los dispositivos se mantuvo próximo a los criterios de análisis adoptados, con énfasis en el área del piso y mesa. Considerando todas las salas y porcentajes de inhibición microbiana, con las dos máquinas, los resultados fueron: piso (100 %), mesa (90 %), pared (50 %) y aire (70 %). Conclusión: Las máquinas generadoras de gas O3 presentaron potencial antimicrobiano como medida de control de microorganismos presentes en superficies y aire interior climatizado artificialmente, lo que lo convierte en un desinfectante factible para ser usado.

Abstract Objective: Assess the antimicrobial action of ozone gas (O3) on surfaces and artificially cooled ambient air. Methods: Cross-sectional experimental/laboratory study carried out in ten rooms of a medical microbiology research lab, with class 2 biosafety risk. The demarcated surfaces on the floor, wall and counter were assessed in relation to the presence or absence of microorganisms, based on collections done with swabs dampened in sterile distilled water, before and after exposure to ozone gas produced by two different generators. After this procedure, each swab was inoculated on the surface of a Brain Heart Infusion Agar DIFCO® (BHI) culture, followed by incubation at 35ºC for 24 hours. For the microbiological analysis of the air, a petri dish with BHI was openly exposed for one hour, before and after treatment with O3 gas, and were incubated according to the same criteria. Results: The antimicrobial activity of the O3 gas produced by both generators was checked in all the areas investigated, with records indicating a decrease in the number of colony-forming units. The antimicrobial inhibition potential of the generators was close to the analysis criteria adopted, particularly for the floor and counter areas. Based on all the rooms and microbial inhibition percentages, in relation to the two generators, the results were: floor (100%), counter (90%), wall (50%) and air (70%). Conclusion: The O3 generators had antimicrobial potential as a procedure for controlling microorganisms present on surfaces and in artificially cooled ambient air, constituting a feasible sanitizer.