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Revista do Instituto de Medicina Tropical de São Paulo

On-line version ISSN 1678-9946

Rev. Inst. Med. trop. S. Paulo vol.26 no.6 São Paulo Nov./Dec. 1984 

In vitro susceptibility of Paracoccidioides brasiliensis yeast form to antifungal agents


Susceptibilidad in vitro de la forma levaduriforme de Paracoccidioides brasiliensis a los agentes antifungicos



Angela Restrepo; Catalina de Bedoutand Angela M. Tabares

Corporación de Investigaciones Biológicas, Hospital Pablo Tobón Uribe, Medellín, Colombia




A study was conducted to determine the susceptibility of P. brasiliensis yeast form to amphotericin B (A), ketoconazole (K), 5-fluorocytosine (5-FC) and rifampin (R). The three isolates tested produced minimal inhibitory concentrations (MICs) (mcg/ml) in the following range: A: 0.09-0.18; K: 0.001-0.007; 5-FC: 62.5-250 and R: 40-80. The minimal fungicidal concentrations (MFC) were several times higher than the corresponding MICs. Precise MFC for 5-FC were not obtained (> 500 mcg/ml). Combination of K plus A proved synergic, with the fractional inhibitory concentration (FIC) indices revealing synergy when the drugs were combined at the 1 to 1 and 1 to 5 MIC ratios. R (40 mcg/ml) appeared to antagonize K. These results indicate promise for the combined use of K plus A as a therapeutical regimen.


Se realizó un estudio con el objeto de determinar la susceptibilidad de la fase levaduri-forme del P. brasiliensis a la Anfotericina B (A), el Ketoconazol (K), la 5-fluorocitosina (5-FC) y la rifampicina. Las 3 cepas estudiadas tuvieron las siguientes concentraciones inhibitorias mínimas (MIC) (mcg/ml) A: 0.09-0.18; K: 0.001-0.007; 5-FC: 62.5-250 y R: 40-80. Las concentraciones fungicidas mínimas (MFC) resultaron más altas que las MICs correspondientes. En el caso de la 5-FC no se obtuvo una cifra MFC precisa (> 500 mcg/ml). La combinación de K más A mostró ser sinérgica al combinarse las drogas en relación 1:1 y 1:5 de los MICs respectivos. R (40 mcg/ml) se mostró antagonista del K. Los resultados indican que la combinación A + K pudiera constituir un adecuado régimen terapéutico en ciertos pacientes.



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This work was supported by the Fondo Colombiano de Investigaciones Científicas (Col-ciencias), Bogotá, (Project Nr. 97145-3-04-80).



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Recebido para publicação em 13/2/1984.

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