Microtiter method for MIC testing with spherule-endospore-phase Coccidioides immitis.
ABSTRACT A method was developed for susceptibility testing with spherule-endospore-phase Coccidioides immitis by using a microtiter format. Isolated endospores were used to inoculate wells containing modified Converse medium with various concentrations of azole or nikkomycin antifungal substances which then were sealed with an acetate film. The plate was incubated at 37 degrees C with shaking for 96 h, after which the control wells had visible turbidity and endpoints were discernible. Microscopic examination revealed that both control and treatment wells maintained cells predominantly in the spherule-endospore phase of growth.
SourceAvailable from: Zoilo Pires de Camargo[Show abstract] [Hide abstract]
ABSTRACT: The aim of the present study was to evaluate the effect of cotrimoxazole on the in vitro susceptibility of Coccidioides posadasii strains to antifungals. A total of 18 strains of C. posadasii isolated in Brazil were evaluated in this study. The assays were performed in accordance with the Clinical and Laboratory Standards Institute guidelines and the combinations were tested using the checkerboard method. The minimum inhibitory concentrations were reduced by 11, 2.4, 4.3 and 3.5 times for amphotericin B, itraconazole, fluconazole and voriconazole, respectively. Moreover, it was seen that cotrimoxazole itself inhibited C. posadasii strains in vitro. The impairment of folic acid synthesis may be a potential antifungal target for C. posadasii.Memórias do Instituto Oswaldo Cruz 12/2011; 106(8):1045-8. DOI:10.1590/S0074-02762011000800024 · 1.57 Impact Factor
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ABSTRACT: In vitro tests employing microdilution to evaluate fungal susceptibility to antifungal drugs are already standardized for fermentative yeasts. However, studies on the susceptibility of dimorphic fungi such as Paracoccidioides brasiliensis employing this method are scarce. The present work introduced some modifications into antifungal susceptibility testing from the European Committee on Antimicrobial Susceptibility Testing (EUCAST), concerning broth medium and reading time, to determine minimal inhibitory concentration (MIC) of amphotericin B and itraconazole against Paracoccidioides brasiliensis. Yeast-like cells of P. brasiliensis (Pb18 strain) were tested for susceptibility to amphotericin B and itraconazole in RPMI 1640 medium, supplemented with 2% glucose and nitrogen source and incubated at 35°C. The MIC of amphotericin B and itraconazole against Pb18 were respectively 0.25 µg/mL and 0.002 µg/mL. The results of minimal fungicidal concentration (MFC) showed that amphotericin B at 0.25 µg/mL or higher concentrations displayed fungicidal activity against Pb18 while itraconazole at least 0.002 µg/mL has a fungistatic effect on P. brasiliensis. In conclusion, our results showed that the method employed in the present study is reproducible and reliable for testing the susceptibility of P. brasiliensis to antifungal drugs.Journal of Venomous Animals and Toxins including Tropical Diseases 01/2009; 15(4). DOI:10.1590/S1678-91992009000400010 · 0.43 Impact Factor
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ABSTRACT: Twelve patients receiving therapy with an azole agent (ketoconazole, itraconazole, and/or fluconazole) for systemic mycoses experienced drug interactions with rifampin, phenytoin, and/or carbamazepine resulting in substantial decreases in azole concentrations in serum. All four patients receiving azoles and concurrent phenytoin and/or carbamazepine failed to respond to treatment or suffered a relapse of their fungal infection. Four of five patients with cryptococcosis who received itraconazole and rifampin responded despite decreases in their serum itraconazole concentrations; synergy between itraconazole and rifampin was documented by in vitro analysis of inhibition and of killing of Cryptococcus neoformans isolates from all patients receiving this combination. In contrast, two patients with coccidioidomycosis failed to respond to itraconazole/rifampin. Moreover, two patients with cryptococcosis suffered a relapse or persistence of seborrheic dermatitis while receiving itraconazole/rifampin. The latter combination showed synergy in vitro in the inhibition of the mycelial phase of Coccidioides immitis and, to a lesser extent, of the pathogenic spherule phase of this fungus; synergy in the killing of C. immitis was not noted, nor was synergy seen against Malassezia furfur, the purported etiologic agent of seborrheic dermatitis. These findings illustrate several drug interactions that may affect clinical outcome and that must be considered in the management of antifungal therapy.Clinical Infectious Diseases 02/1992; 14(1):165-74. DOI:10.1093/clinids/14.1.165 · 9.42 Impact Factor