Candida Infection Biology – fungal armoury, battlefields ... - FINSysB

Poster number: 38
Alkali-metal-cation homeostasis of Candida species is
affected by subinhibitory concentrations of azoles
Hana Elicharová, Hana Sychrová
Department of Membrane Transport, Institute of Physiology AS CR, v. v. i., Videnska 1083,
14220 Prague, Czech Republic, elicharova@biomed.cas.cz
Homeostasis of alkali-metal cations is essential for all living cells including the
pathogenic Candida species. Candida cells sustain high internal concentration of
potassium cations that are involved in osmotic and pH regulations, enzymatic
function and other processes. In contrast, Candida cells keep the internal
concentration of sodium low due to its intracellular toxicity. Plasma membrane and
transporters play a key role in maintenance of cation homeostasis. Azoles form the
most important group of drugs with antifungal activity. They destabilize plasma
membrane of Candida cells. The combination of subinhibitory concentrations of
fluconazole and NaCl has been shown to inhibit the growth of both fluconazolesensitive
and fluconazole-resistant C. albicans strains (1).
We have tested the influence of subinhibitory concentrations of azoles on the alkalimetal-cation
homeostasis of four Candida species (C. albicans, C. dubliniensis,
C. parapsilosis and C. glabrata).We have found that all tested Candida species can
generally tolerate high concentrations of azoles or salts separately, but the
combination of both compounds inhibits their growth effectively. The level of
inhibition of single Candida species differs strongly. Presence of subinhibitory
concentration of fluconazole increases the intracellular content of toxic Na + in all
four Candida species. Estimation of relative membrane potential together with the
use of Candida mutants lacking plasma-membrane transporters of alkali metal
cations should explain how alkali-metal-cation homeostasis is affected by presence
of fluconazole.
(1) Kolecka et al., Can J Microbiol 2009 55(5):605-10
Supported by MSMT LC531
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