Terpinen-4-ol, tyrosol, and ß-lapachone as potential antifungals against dimorphic fungi

Abstract This study aimed to evaluate the in vitro antifungal activity of terpinen-4-ol, tyrosol, and β-lapachone against strains of Coccidioides posadasii in filamentous phase (n = 22) and Histoplasma capsulatum in both filamentous (n = 40) and yeast phases (n = 13), using the broth dilution methods as described by the Clinical and Laboratory Standards Institute, to determine the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of these compounds. The mechanisms of action of these compounds were also investigated by analyzing their effect on cell membrane permeability and ergosterol synthesis. The MIC and MFCf these compounds against C. posadasii, mycelial H. capsulatum, and yeast-like H. capsulatum, were in the following ranges: 350-5720 µg/mL, 20-2860 µg/mL, and 40-1420 µg/mL, respectively for terpinen-4-ol; 250-4000 µg/mL, 30-2000 µg/mL, and 10-1000 µg/mL, respectively, for tyrosol; and 0.48-7.8 µg/mL, 0.25-16 µg/mL, and 0.125-4 µg/mL, respectively for β-lapachone. These compounds showed a decrease in MIC when the samples were subjected to osmotic stress, suggesting that the compounds acted on the fungal membrane. All the compounds were able to reduce the ergosterol content of the fungal strains. Finally, tyrosol was able to cause a leakage of intracellular molecules.

Antiretroviral drugs saquinavir and ritonavir reduce inhibitory concentration values of itraconazole against Histoplasma capsulatum strains in vitro

Abstract Recent studies have shown that some drugs that are not routinely used to treat fungal infections have antifungal activity, such as protease inhibitor antiretroviral drugs. This study investigated the in vitro susceptibility of Histoplasma capsulatum var. capsulatum to saquinavir and ritonavir, and its combination with the antifungal itraconazole. The susceptibility assay was performed according to Clinical and Laboratory Standards Institute guidelines. All strains were inhibited by the protease inhibitor antiretroviral drugs. Saquinavir showed minimum inhibitory concentrations ranging from 0.125 to 1 μg mL−1 for both phases, and ritonavir presented minimum inhibitory concentrations ranging from 0.0312 to 4 μg mL−1and from 0.0625 to 1 μg mL−1 for filamentous and yeast phase, respectively. Concerning the antifungal itraconazole, the minimum inhibitory concentration values ranged from 0.0019 to 0.125 μg mL−1 and from 0.0039 to 0.0312 μg mL−1 for the filamentous and yeast phase, respectively. The combination of saquinavir or ritonavir with itraconazole was synergistic against H. capsulatum, with a significant reduction in the minimum inhibitory concentrations of both drugs against the strains (p < 0.05). These data show an important in vitro synergy between protease inhibitors and itraconazole against the fungus H. capsulatum.

Aeromonas spp. isoladas no Ceará - Brasil: detecção genotípica de fatores de virulência esensibilidade a antimicrobianos in vitro

Espécies do gênero Aeromonas, encontradas com frequência em ambientes aquáticos,são importantes patógenos humanos. Este estudo teve como objetivo geral isolar cepasclínicas e ambientais de Aeromonas spp., assim como, investigar a presença de genes devirulência e avaliar a sensibilidade a antimicrobianos in vitro, bem como, o mecanismo deresistência. As amostras clínicas e ambientais foram identificadas por meio de testesbioquímicos e metodologia automatizada Vitek2® (bioMeriéux). A detecção de genes devirulência para enterotoxina citotóxica (act), hemolisina (asa1) e sistema de secreção III(ascV) foi feita por PCR simples. A sensibilidade aos antimicrobianos seguiu recomendaçõesdos documentos M7-A9 e M45-A2 do CLSI. A caracterização do mecanismo de resistênciafoi realizada mediante testes fenotípicos para detecção de ß-lactamases. Dos isolados clínicosforam identificados dezenove A. hydrophila, três A. veronii bv. sobria e uma A. caviae. As 35cepas ambientais foram identificadas como A. hydrophila (n=11), A. veronii bv. sobria(n=22), A. veronii bv. veronii (n=1) e A. caviae (n=1). Em relação aos genes de virulência dascepas clínicas, foram detectados os genes act, asa1 e ascV nas proporções 69,5; 8,6 e 34,7%,respectivamente. Enquanto nas cepas ambientais foram encontrados os percentuais de 51,4;45,7 e 54,2%, respectivamente. Observou-se resistência a piperacilina-tazobactam e aamoxicilina-clavulanato, em 3 e 15 cepas clínicas, respectivamente. Ademais, houveresistência a ceftazidima, meropenem, imipenem, ciprofloxacina e trimetoprimsulfametoxazol,com uma cepa resistente a cada antimicrobiano. Quanto às cepas ambientais,detectou-se resistência somente a piperacilina-tazobactam e amoxicilina-clavulanato em 1 e17 cepas, respectivamente...

Aeromonas spp., frequently found in aquatic environments, are important human pathogens.This study had the main objectives of isolating clinical and environmental strains ofAeromonas spp. and investigating the presence of virulence genes, antimicrobial susceptibilityin vitro and resistance mechanism. Clinical and environmental samples were identified bybiochemical tests and the automated Vitek2® (bioMeriéux) method. The virulence genescytotoxic enterotoxin (act), haemolysin (asa1) and type III secretion system (ascV) weredetected by simple PCR. The antimicrobial susceptibility was determined according to therecommendations of M7-A9 and M45-A2 do CLSI. The characterization of resistancemechanism was performed by detection of ß-lactamases phenotypic tests. From the clinicalisolates, 19 A. hydrophila, 3 A. veronii bv. sobria and 1 A. caviae were identified The 35environmental strains were identified as A. hydrophila (n= 11), A. veronii bv. sobria (n= 22),A. veronii bv. veronii (n= 1) and A. caviae (n= 1). Regarding the virulence genes of clinicalstrains, the act, asa1 and ascV genes were detected in the proportions 69.5, 8.6 and 34.7%,respectively. The respective percentages for the environmental strains were 51.4, 45.7% and54.2%. Resistance was observed to piperacillin-tazobactam and amoxicillin-clavulanate in 3and 15 clinical strains, respectively. Moreover, there was resistance to ceftazidime,meropenem, imipenem, ciprofloxacin and trimethoprim-sulfamethoxazole, with one strainresistant to each antimicrobial agent. As for the environmental strains, resistance was detectedonly to piperacillin-tazobactam and amoxicillin-clavulanate and, in 1 and 17 strains,respectively...