Multidrug-resistant Candida glabrata strains obtained by induction of anidulafungin resistance in planktonic and biofilm cells

Candida glabrata has emerged as a common cause of serious life-threatening fungal infections, largely owing to their low susceptibility to azole antifungals. Recent guidance indicates the use of echinocandins as the first-choice drug for the treatment of systemic infections of C. glabrata; however, C. glabrata resistance to echinocandins is reportedly increasing. Herein, we present the induction of anidulafungin resistance in planktonic and sessile cells of C. glabrata and the development of fluconazole crossresistance. MICs of 21 clinical C. glabrata strains were determined by a broth microdilution method using anidulafungin and fluconazole. Biofilm formation on a tracheal catheter was determined using 1- × 1-cm2 polyvinyl polychloride catheter fragments. Induction of anidulafungin resistance in planktonic and sessile cells and evaluation of its stability were performed by exposing the strains to successively higher concentrations of the antifungal. The induction resulted in strains strongly resistant to anidulafungin (MICs: 1−2 μg/mL) and fluconazole (≥64 μg/mL). Most of the sessile cells of C. glabrata presented slightly reduced susceptibility compared with the planktonic cells. Clinically, this cross-resistance could lead to therapeutic failure while using fluconazole in patients previously exposed to subinhibitory concentrations of anidulafungin for extended periods

Molecular and cellular characterization of the biological effects of ruthenium(II) complexes incorporating 2-Pyridyl-2-Pyrimidine-4-Carboxylic acid

A great majority of the Ru complexes currently studied in anticancer research exert their antiproliferative activity, at least partially, through ligand exchange. In recent years, however, coordinatively saturated and substitutionally inert polypyridyl Ru(II) compounds have emerged as potential anticancer drug candidates. In this work, we present the synthesis and detailed characterization of two novel inert Ru(II) complexes, namely, [Ru(bipy)(2)(Cpp-NH-Hex-COOH)](2+) (2) and [Ru(dppz)(2)(CppH)](2+) (3) (bipy = 2,2'-bipyridine; CppH = 2-(2'-pyridyl)pyrimidine-4-carboxylic acid; Cpp-NH-Hex-COOH = 6-(2-(pyridin-2-yl)pyrimidine-4-carboxamido)hexanoic acid; dppz = dipyrido[3,2-a:2',3'-c]phenazine). 3 is of particular interest as it was found to have IC(50) values comparable to cisplatin, a benchmark standard in the field, on three cancer cell lines and a better activity on one cisplatin-resistant cell line than cisplatin itself. The mechanism of action of 3 was then investigated in detail and it could be demonstrated that, although 3 binds to calf-thymus DNA by intercalation, the biological effects that it induces did not involve a nuclear DNA related mode of action. On the contrary, confocal microscopy colocalization studies in HeLa cells showed that 3 specifically targeted mitochondria. This was further correlated by ruthenium quantification using High-resolution atomic absorption spectrometry. Furthermore, as determined by two independent assays, 3 induced apoptosis at a relatively late stage of treatment. The generation of reactive oxygen species could be excluded as the cause of the observed cytotoxicity. It was demonstrated that the mitochondrial membrane potential in HeLa was impaired by 3 as early as 2 h after its introduction and even more with increasing time