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In vitro action of some disinfectants on Paracoccidioides brasiliensis yeast forms
M A Shikanai-Yasuda1, R T Taguchi, M K Sato
1Depto. de Doenças Infecciosas e Parasitárias da FM-USP, Hospital das Clínicas da FM-USP (LIM-48), São Paulo, Brasil.
Abstract:
The fungicidal action of sodium hypochlorite (0.3, 1, 2.5, 5 and 10%); formaldehyde (2, 5, and 10%); and ethyl alcohol (70%) on yeast forms of Paracoccidioides brasiliensis Pb 18 and a newly-isolated Goiana strain was described. Contact between the fungus and the disinfectants was maintained for 1, 2, 24, 48 and 72 hours at room temperature. Viability was evaluated by the fluorescein diacetate-ethidium bromide treatment, culture in solid and liquid media (36 degrees C and 26 degrees C); yeast to mycelial germination at room temperature; and radiometric study of metabolic activity. All concentrations of disinfectants were found to be effective in inactivating Pb 18 and Goiana strains, except for the 1-hour contact with 2% formaldehyde, in which fluorescein diacetate-ethidium bromide treatment was found to reveal 40 and 27% of viable cells, respectively. The yeast to mycelial germination method was considered to reveal faster and similar results as compared to culture in solid and liquid media.
Insights
Sodium hypochlorite, formaldehyde, and ethyl alcohol effectively inactivated Paracoccidioides brasiliensis strains. Yeast to mycelial germination proved a rapid method for assessing disinfectant efficacy.
Area of Science:
- Mycology
- Antimicrobial Efficacy
- Infectious Diseases
Background:
- Paracoccidioides brasiliensis is a fungus causing paracoccidioidomycosis.
- Effective disinfection protocols are crucial for controlling fungal infections.
Purpose of the Study:
- To evaluate the fungicidal activity of sodium hypochlorite, formaldehyde, and ethyl alcohol against Paracoccidioides brasiliensis.
- To compare different methods for assessing fungal viability after disinfectant exposure.
Main Methods:
- Yeast forms of P. brasiliensis strains (Pb 18 and Goiana) were exposed to disinfectants for varying durations.
- Fungal viability was assessed using fluorescein diacetate-ethidium bromide staining, culture methods, yeast-to-mycelial transition, and radiometric analysis.
Main Results:
- All tested concentrations of sodium hypochlorite, formaldehyde, and ethyl alcohol demonstrated fungicidal activity.
- 2% formaldehyde showed reduced efficacy at 1-hour contact, with 40% and 27% viable cells detected by vital staining.
- Yeast-to-mycelial germination provided faster and comparable results to traditional culture methods.
Conclusions:
- Sodium hypochlorite, formaldehyde, and ethyl alcohol are effective disinfectants against P. brasiliensis.
- Yeast-to-mycelial germination is a rapid and reliable method for evaluating disinfectant effectiveness on P. brasiliensis.