Tatiana Spader

Antifungal Susceptibilities of Sporothrix albicans, S. brasiliensis, and S. luriei of the S. schenckii Complex Identified in Brazil

ABSTRACT We studied 40 strains of the species complex formerly classified as the single species Sporothrix schenckii to identify new species within this complex and evaluate their antifungal susceptibility profiles. Based on phenotypic tests (ability to grow at 37°C, colony diameters, and pigmentation of the colonies, as well as assimilation of sucrose and raffinose) and molecular assays (amplification of a fragment of the calmodulin gene), here we report the identification of S. albicans, S. brasiliensis, S. luriei, and S. schenckii; two isolates of these species were detected as itraconazole-resistant strains.

In Vitro Activity of Terbinafine Combined with Caspofungin and Azoles against Pythium insidiosum

ABSTRACT In this text we evaluated the in vitro antifungal activities of terbinafine combined with caspofungin, miconazole, ketoconazole, and fluconazole against 17 Pythium insidiosum strains by using the microdilution checkerboard method. Synergistic interactions were observed with terbinafine combined with caspofungin (41.2% of the strains), fluconazole (41.2%), ketoconazole (29.4%), and miconazole (11.8%). No antagonistic effects were observed. The combination of terbinafine plus caspofungin or terbinafine plus fluconazole may have significant therapeutic potential for treatment of pythiosis.

In vitro activity of terbinafine associated to amphotericin B, fluvastatin, rifampicin, metronidazole and ibuprofen against Pythium insidiosum.

We evaluated the in vitro activities of terbinafine alone and in combination with amphotericin B, fluvastatin, rifampicin, metronidazole or ibuprofen against 17 clinical isolates of Pythium insidiosum. The assays were based on technique M38-A2, as well as the checkerboard microdilution method. The main synergism observed was by combination of terbinafine plus amphotericin B (41.18%). Antagonisms were observed in combinations of terbinafine with fluvastatin (35.30%) or rifampicin (5.88%).

Antimicrobial and cytotoxic activities of leaves, twigs and stem bark of Scutia buxifolia Reissek

The antimicrobial and cytotoxic activities of the dichloromethane, ethyl acetate and butanolic fractions from the leaves, twigs and stem bark of Scutia buxifolia were evaluated using the broth microdilution method and the brine shrimp lethality method, respectively. Phytochemical analysis was performed by thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC). The antimicrobial results demonstrated that the strongest effect occurred with the butanol fraction from the twigs and the ethyl acetate fraction from the stem bark against Saccharomyces cerevisiae (minimal inhibitory concentration; MIC = 62.5 µg mL−1), whereas the ethyl acetate and butanolic fractions from the twigs and stem bark were effective against Pseudomonas aeruginosa and Staphylococcus aureus, with MIC values ranging from 125 to 500 µg mL−1. LD50 values varied from 50.00 ± 0.22 to 82.23 ± 0.34 µg mL−1. Quercetin, quercitrin, isoquercitrin and rutin were identified by HPLC and may be partially responsible for the antimicrobial activities observed. This study reports for the first time the antimicrobial and cytotoxic activities of S. buxifolia leaves, twigs and stem bark.

Synergysm of voriconazole or itraconazole with other antifungal agents against species of Fusarium.

BACKGROUND Infections caused by Fusarium are difficult to treat because these fungi show in vitro and in vivo resistance to practically all the antifungal agents available, which explains the high mortality rates. An attempt to overcome fungal resistance is the combination of antifungal agents, especially those with different mechanisms of action. AIMS Evaluate the in vitro interactions of combinations of voriconazole or itraconazole with other antifungal agents against 32 isolates of Fusarium spp.: Fusarium chlamydosporum, Fusarium oxysporum, Fusarium proliferatum and Fusarium solani. METHODS Drug interactions were assessed by a checkerboard microdilution method that also included the determination of the MIC of each drug alone according to CLSI (Clinical and Laboratory Standards Institute) document M38-A2, 2008. RESULTS The best combinations were voriconazole+terbinafine which showed synergism against 84% of Fusarium strains. Other synergistic combinations were voriconazole+itraconazole (50%), voriconazole+fluconazole (50%), voriconazole+miconazole (38%), voriconazole+flucytosine (22%) and voriconazole+ketoconazole (25%). The synergisms observed with itraconazole combinations were itraconazole+terbinafine (25%) and itraconazole+flucytosine (9.37%). The antagonisms observed were: voriconazole+fluconazole (3%) and itraconazole+flucytosine (12.5%). CONCLUSIONS The synergism showed by voriconazole+terbinafine was remarkable. To better elucidate the potential usefulness of our findings, new in vivo and in vitro studies deserve be performed.

In vitro interactions between amphotericin B and other antifungal agents and rifampin against Fusarium spp.

Fusarium species are common hyaline soil saprophytes and plant pathogens that are opportunistic fungal pathogens of immunocompromised patients. The treatment for fusariosis remains uncertain with an unfavourable prognosis; new possibilities for treatment, such as various synergistic drug interactions, must be uncovered. In this study, we evaluated the in vitro interactions of amphotericin B with caspofungin, ketoconazole, 5‐flucytosine, itraconazole, miconazole, rifampin, fluconazole, terbinafine and voriconazole against isolates of Fusarium spp. using the chequerboard method with interactions evaluated by fractional inhibitory concentration indices. The highest percentages of synergistic interactions were observed for the combinations of amphotericin B and caspofungin (68.7%), amphotericin B and rifampin (68.7%), amphotericin B plus 5‐flucytosine (59.3%) and amphotericin B with voriconazole (37.5%). The pattern of susceptibility to antifungal agents among Fusarium species and their consequence on the effects of drug combinations are also discussed.

In vitro synergisms obtained by amphotericin B and voriconazole associated with non-antifungal agents against Fusarium spp

Fusarium spp is an opportunistic fungal pathogen responsible for causing invasive hyalohyphomycosis in immunocompromised patients. Due to its susceptibility pattern with a remarkable resistance to antifungal agents the treatment failures and mortality rates are high. To overcome this situation, combination therapy may be considered which must be subjected to in vitro tests. In vitro activities of amphotericin B, itraconazole, and voriconazole associated with azithromycin, ciprofloxacin, fluvastatin, ibuprofen, metronidazole, and also the combination of amphotericin B plus rifampin against 23 strains of Fusarium spp. through the checkerboard technique based on M38-A2 [Clinical and Laboratory Standards Institute (2008). Reference method for broth dilution antifungal susceptibility testing of filamentous fungi; approved standard, 2nd ed. (CLSI document M38-A2) (ISBN 1-56238-668-9). Wayne, PA: CLSI] were evaluated. The best synergistic interactions with amphotericin B were with ibuprofen (43.5%) (FICI [fractional inhibitory concentration index] range = 0.25-2). Combinations with voriconazole showed synergism, mainly with ciprofloxacin (30.4%) (FICI range = 0.25-3) and metronidazole (30.4%) (FICI range = 0.1-4); however, all the combinations with itraconazole were indifferent. In general, antagonistic interactions were not registered. Our results showed that in vitro synergisms obtained by some combinations studied deserve attention since they were better than those showed by the antimycotic.

In vitro antimicrobial and antioxidant activities of a crude extract and fractions from Buddleja thyrsoides Lam. leaves.

Crude extract and fractions of Buddleja thyrsoides were investigated regarding antioxidant activities by DPPH, total phenolic contents by Folin-Ciocalteau and antimicrobial activity by the broth microdilution method. Total phenolics varied from 214.07 ± 3.6 to 438.4 ± 0.3 mg g-1. Crude extract, ethyl acetate, dichloromethane and butanolic fractions exhibited a weak scavenging activity (SC50=186.04 ± 10.8, 137.70 ± 8.5, 146.89 ± 9.0 and 165.71 ± 3.2 µg mL-1, respectively). A correlation between the antioxidant activities and total phenolic contents could be shown (r=0.857, p<0.01). The lowest value of MIC was observed with butanolic fraction against Saccharomyces cerevisiae (MIC and MFC at 62.5 µg mL-1). Dichloromethane and ethyl acetate fractions were effective against Staphylococcus aureus with MIC value at 250 and 500 µg mL-1 respectively.

Reavaliação da suscetibilidade de candida a anfotericina B : estudo comparativo com isolados de três hospitais do estado do Rio Grande do Sul

Susceptibility to amphotericin B was compared between isolates of Candida spp that were obtained from candidemia cases as follows: 41 from Hospital Universitario de Santa Maria, 56 from Hospital de Clinicas, Porto Alegre, and 47 from the Santa Casa hospital complex, Porto Alegre. The tests were based on the document M27-A2 from the Clinical Laboratory Standards Institute, but with 20 concentrations of amphotericin B ranging from 0.1 to 2mg/ml. The tests were carried out using RPMI 1640 medium with glucose, antibiotic medium 3 and yeast nitrogen base-dextrose. The antibiotic medium 3 broth generated wide ranges of minimum inhibitory concentrations and minimum fungicidal concentrations in relation to the other agents. The variations in susceptibility between the hospitals were best detected in antibiotic medium 3. The isolates from Hospital Universitario de Santa Maria showed lower susceptibility than did those from the Santa Casa hospital complex, Porto Alegre (p < 0.05). The causes of the susceptibility variations were not assessed but they indicate the need for surveillance regarding the susceptibility to amphotericin B.

INFECÇÕES CAUSADAS POR MALASSEZIA: NOVAS ABORDAGENS

O genero Malassezia compreende fungos leveduriformes lipofilicos e lipodependentes que recentemente sofreram mudancas em sua classificacao taxonomica, com a introducao de quatro novas especies: M. globosa, M. obtusa, M. slooffiae e M. restricta, alem das especies M. furfur, M. pachydermatis e M. sympodialis, anteriormente descritas. Estes fungos estao associados a varios quadros patologicos que incluem infeccoes como a pitiriase versicolor, dermatite seborreica, dermatite atopica, fungemia, entre outros. Estes quadros eram, ate pouco tempo atras, considerados exclusivamente causados pela especie M. furfur. As mudancas na classificacao taxonomica do genero Malassezia levaram a uma reavaliacao dos procedimentos laboratoriais utilizados para a identificacao deste agente etiologico. Entre eles podemos citar o estudo e a caracterizacao morfologica das especies, sua tolerância termica, suas necessidades nutricionais para determinados tipos de acidos graxos, bem como a composicao e as caracteristicas do DNA de cada uma delas.