Effect of fluoxetine on planktonic and biofilm growth and the antimicrobial susceptibility of Burkholderia pseudomallei.

Aim: This study evaluated the effect of fluoxetine (FLU) on planktonic and biofilm growth and the antimicrobial susceptibility of Burkholderia pseudomallei. Materials & methods: The minimum inhibitory concentrations (MICs) for FLU were determined by broth microdilution. Its effect on growing and mature biofilms and its interaction with antibacterial drugs were evaluated by assessing biofilm metabolic activity, biomass and structure through confocal microscopy. Results: The FLU MIC range was 19.53-312.5 µg/ml. FLU eradicated growing and mature biofilms of B. pseudomallei at 19.53-312.5 µg/ml and 1250-2500 µg/ml, respectively, with no structural alterations and enhanced the antibiofilm activity of antimicrobial drugs. Conclusion: These results bring perspectives for the use of FLU in the treatment of melioidosis, requiring further studies to evaluate its applicability.

Terpinen-4-ol inhibits the growth of Sporothrix schenckii complex and exhibits synergism with antifungal agents.

Aim: This study investigated the effect of terpinen-4-ol against Sporothrix schenckii complex and its interactions with antifungals. Materials & methods: The antifungal activity of terpinen-4-ol was evaluated by broth microdilution. The potential effect on cellular ergosterol concentration was evaluated by spectrophotometry. The antibiofilm activity was evaluated by violet crystal staining and XTT reduction assay. The potential pharmacological interactions with antifungals were evaluated by the checkerboard assay. Results: terpinen-4-ol (T-OH) showed minimal inhibitory concentrations ranging from 4 to 32 mg/l decreasing cellular ergosterol content and presented a SMIC ranging from 64 to 1024 mg/l for Sporothrix spp. The combinations of T-OH with itraconazole or terbinafine were synergistic. Conclusion: T-OH has antifungal activity against Sporothrix spp. and acts synergistically with standard antifungals.

Pentamidine inhibits the growth of Sporothrix schenckii complex and exhibits synergism with antifungal agents.

AIM: The purpose of this study was to evaluate the effects of the antileishmanials meglumine antimoniate and pentamidine against Sporothrix schenckii complex. MATERIALS & METHODS: The antifungal activity of the two antileishmanials was assessed by broth microdilution. The interaction between the antileishmanials and antifungal drugs (amphotericin B, itraconazole and terbinafine) was evaluated by the checkerboard assay. The effect of prior exposure of Sporothrix spp. yeast cells to antileishmanials was evaluated by broth microdilution. RESULTS: Only pentamidine showed antifungal activity against Sporothrix spp. Synergistic interactions were observed between pentamidine and the antifungals. Also, the pre-exposure to meglumine antimoniate reduced the susceptibility of Sardinella brasiliensis and S. schenckii sensu stricto to amphotericin B and itraconazole. CONCLUSION: Pentamidine showed antifungal activity against Sporothrix spp., indicating it is a possible therapeutic alternative for the treatment of sporotrichosis.

Phenotype-driven strategies for screening Candida parapsilosis complex for molecular identification

Abstract In this study, phenotypic methods presented >80% agreement with the molecular identification of 59 Candida parapsilosis complex. Growth at 15% NaCl or pH 7.0 significantly reduced cfu-counts of Candida orthopsilosis, suggesting these conditions may support the development of phenotypic methods for the differentiation of the cryptic species of C. parapsilosis complex.

Azole resistance in Candida spp. isolated from Catú Lake, Ceará, Brazil: an efflux-pump-mediated mechanism

Abstract Since, there is no study reporting the mechanism of azole resistance among yeasts isolated from aquatic environments; the present study aims to investigate the occurrence of antifungal resistance among yeasts isolated from an aquatic environment, and assess the efflux-pump activity of the azole-resistant strains to better understand the mechanism of resistance for this group of drugs. For this purpose, monthly water and sediment samples were collected from Catú Lake, Ceará, Brazil, from March 2011 to February 2012. The obtained yeasts were identified based on morphological and biochemical characteristics. Of the 46 isolates, 37 were Candida spp., 4 were Trichosporon asahii, 3 were Cryptococcus laurentii, 1 Rhodotorula mucilaginosa, and 1 was Kodamaea ohmeri. These isolates were subjected to broth microdilution assay with amphotericin B, itraconazole, and fluconazole, according to the methodology standardized by the Clinical and Laboratory Standards Institute (CLSI). The minimum inhibitory concentrations (MICs) of amphotericin B, itraconazole, and fluconazole were 0.03125–2 µg/mL, 0.0625 to ≥16 µg/mL, and 0.5 to ≥64 µg/mL, respectively, and 13 resistant azole-resistant Candida isolates were detected. A reduction in the azole MICs leading to the phenotypical reversal of the azole resistance was observed upon addition of efflux-pump inhibitors. These findings suggest that the azole resistance among environmental Candida spp. is most likely associated with the overexpression of efflux-pumps.