title: Antifungal activity of clotrimazole against Candida albicans depends on carbon sources, growth phase and morphology.
abstract: Vulvovaginal candidiasis, a superficial infection caused predominantly by the pathogenic fungus Candida albicans, is frequently treated with clotrimazole. Some drug formulations contain lactate for improved solubility. Lactate may modify C. albicans physiology and drug sensitivity by serving as a carbon source for the fungus and/or affecting local pH. Here, we explored the effects of lactate, in combination with pH changes, on C. albicans proliferation, morphology and clotrimazole sensitivity. Moreover, we determined the influence of growth phase and morphology per se on drug sensitivity. We showed that utilization of lactate as a carbon source did not promote fast fungal proliferation or filamentation. Lactate had no influence on clotrimazole-mediated killing of C. albicans in standard fungal cultivation medium but had an additive effect on the fungicidal clotrimazole action under in vitro vagina-simulative conditions. Moreover, clotrimazole-mediated killing was growth-phase and morphology dependent. Post-exponential cells were resistant to the fungicidal action of clotrimazole, whilst logarithmic cells were sensitive, and hyphae showed the highest susceptibility. Finally, we showed that treatment of pre-formed C. albicans hyphae with sublethal concentrations of clotrimazole induced a reversion to yeast-phase growth. As C. albicans hyphae are considered the pathogenic morphology during mucosal infections, these data suggest that elevated fungicidal activity of clotrimazole against hyphae plus clotrimazole-induced hyphae-to-yeast reversion may help to dampen acute vaginal infections by reducing the relative proportion of hyphae and thus shifting to a non-invasive commensal-like population. In addition, lactate as an ingredient of clotrimazole formulations may potentiate clotrimazole killing of C. albicans in the vaginal microenvironment.
authors.affiliation: Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, Jena, Germany.
authors.forename: Lydia
authors.initials: L
authors.lastname: Kasper
authors.affiliation: Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, Jena, Germany.
authors.forename: Pedro
authors.initials: P
authors.lastname: Miramón
authors.affiliation: Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, Jena, Germany.
authors.forename: Nadja
authors.initials: N
authors.lastname: Jablonowski
authors.affiliation: Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, Jena, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Wisgott
authors.affiliation: Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, Jena, Germany.
authors.forename: Duncan
authors.initials: D
authors.lastname: Wilson
authors.affiliation: Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, Jena, Germany.|Integrated Research and Treatment Center, Sepsis und Sepsisfolgen, Center for Sepsis Control and Care (CSCC), University Hospital, Jena, Germany.
authors.forename: Sascha
authors.initials: S
authors.lastname: Brunke
authors.affiliation: Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, Jena, Germany.|Integrated Research and Treatment Center, Sepsis und Sepsisfolgen, Center for Sepsis Control and Care (CSCC), University Hospital, Jena, Germany.|Friedrich Schiller University, Jena, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Hube
mesh_terms: D000935:Antifungal Agents / Q000627:therapeutic use; D002176:Candida albicans / Q000187:drug effects* / Q000254:growth & development*; D002181:Candidiasis, Vulvovaginal / Q000188:drug therapy*; D049109:Cell Proliferation / Q000187:drug effects; D003022:Clotrimazole / Q000627:therapeutic use*; D025141:Drug Resistance, Fungal; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D025301:Hyphae / Q000187:drug effects / Q000472:pathogenicity; D019344:Lactic Acid / Q000378:metabolism / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D014621:Vagina / Q000382:microbiology
chemical_list: D000935:Antifungal Agents; D019344:Lactic Acid; D003022:Clotrimazole