Effect of silver nanoparticles alone and in combination with fluconazole on Candida albicans

Silver nanoparticles (SNP) alone and in combination (Combi) with the antibiotic fluconazole (Flu) were explored for their effective role in controlling Candida albicans. The C. albicans isolates used were identified by amplifying the ITS region of rDNA with primers ITS 5 and ITS 4. The MIC of the SNP and Flu alone and in conjunction with each other were assayed by the micro dilution plate method and checkerboard assay respectively. The synergistic effects of SNP and Flu were established by calculating the fractional inhibitory concentration (FIC) index. The effects of these treatments (½ MIC) on budding and on germ tube formation were determined. The identity of all five isolates as C. albicans was confirmed by molecular analysis of ITS rDNA regions and BLAST search. The MIC of SNP alone against C. albicans isolates ranged from 24 to 12 µg/ml and Flu alone was found to be 20 µg/ml. The FIC index of the Combi treatment ranged from 0.125 to 0.5 against C. albicans isolates. The average percent reduction in budding of 5 isolates by SNP, Flu, and Combi was 78.2%, 72.4%, and 92.6% respectively. A notable reduction in germ tube development in C. albicans isolates treated with SNP, Flu, and Combi (95%, 75.6%, and 99.2%. respectively) was recorded. The findings clearly prove that the SNP and Flu have synergistic effects on C. albicans. Further investigation can be undertaken to develop a strategy for utilizing silver nanoparticles with antibiotics to treat Candida infection