Susceptibility of Candida albicans to peroxidase-catalyzed oxidation products of thiocyanate, iodide and bromide

Abstract

The susceptibility of Candida albicans (ATCC 10231 and wild strains) to hypo(pseudo)halous ions (OSCN-, OBr-, OI-) produced by the lactoperoxidase system was tested. Six strains of Candida albicans were isolated from swabs taken from the mouths of children with orthodontic appliances and selected on Sabouraud-Chloramphenicol-Actidione agar plates. The survival rate of Candida blastospores after a 30 min exposure to lactoperoxidase system ranged from 79 to 105% in the presence of 615 microM thiocyanate, from 56 to 88% in the presence of 345 microM bromide and from 0 to 4% in the presence of 250 microM iodide. Results showed that only OI- could exert a strong inhibiting effect in vitro on Candida albicans at physiological concentrations. Nevertheless, the activity of the hypoiodite generating system in saliva was found to be under the control of thiocyanate concentration.