IADR Abstract Archives
Chitosan as Antifungal Agent against Multidrug-Efflux Pump-Mediated Drug-Resistant Candida albicans
Objectives: Overexpression of multidrug-efflux pumps, CaCDR1 and CaCDR2, is a major mechanism of antifungal drug resistance in Candida albicans (Ca). To investigate whether chitosan, a natural product with antifungal activity, would be useful as an effective antifungal agent against drug resistant candidiasis, we aim to test if these efflux pumps also affect fungal susceptibility to chitosan.
Methods: We used 2 approaches to examine the role of CaCDR1 and CaCDR2: (1) overexpression of CaCDR1 or CaCDR2 in a Saccharomyces cerevisiae ADΔ strain, a model yeast strain that lacks 7 efflux pump genes, and (2) deletion of CaCDR1 and/or CaCDR2 genes in C.albicans (SC5314) by using a CRISPR/Cas9 system. The fungal susceptibility to two types of shrimp chitosan, oligomer (7-9 kDa) and polymer (900-1,000 kDa), was tested in broth dilution assays. Log-phase cultures (106 cells/ml) were inoculated into YPD (Yeast-Peptone-Dextrose) broth containing chitosan at various concentrations, incubated for 14 hours at 30°C, and plated on YPD agar for viable cell quantification.
Results: In S.cerevisiae model, the ADΔ strain is highly sensitive to both types of chitosan. We found that yeast cells with overexpression of CaCDR1 or CaCDR2 showed similar susceptibility to chitosan as the ADΔ parent strain. This suggests that CaCDR1 or CaCDR2 overexpression did not remarkably increase fungal resistance to chitosan. In C.albicans, CaCDR1 and CaCDR2 homozygous deletion showed the same level of susceptibility to chitosan as wild type yeast. This suggests that CaCDR1 and CaCDR2 efflux pumps are not required for yeast survival when exposed to chitosan.
Conclusions: Our results showed that neither overexpression nor deletion of CaCDR1 and CaCDR2 efflux pumps affect Ca susceptibility to chitosan, suggesting that drug resistant Ca that overexpresses CaCDR1 or CaCDR2 likely remain susceptible to chitosan. Thus, chitosan may be a useful antifungal agent in cases with drug resistant candidiasis.
Methods: We used 2 approaches to examine the role of CaCDR1 and CaCDR2: (1) overexpression of CaCDR1 or CaCDR2 in a Saccharomyces cerevisiae ADΔ strain, a model yeast strain that lacks 7 efflux pump genes, and (2) deletion of CaCDR1 and/or CaCDR2 genes in C.albicans (SC5314) by using a CRISPR/Cas9 system. The fungal susceptibility to two types of shrimp chitosan, oligomer (7-9 kDa) and polymer (900-1,000 kDa), was tested in broth dilution assays. Log-phase cultures (106 cells/ml) were inoculated into YPD (Yeast-Peptone-Dextrose) broth containing chitosan at various concentrations, incubated for 14 hours at 30°C, and plated on YPD agar for viable cell quantification.
Results: In S.cerevisiae model, the ADΔ strain is highly sensitive to both types of chitosan. We found that yeast cells with overexpression of CaCDR1 or CaCDR2 showed similar susceptibility to chitosan as the ADΔ parent strain. This suggests that CaCDR1 or CaCDR2 overexpression did not remarkably increase fungal resistance to chitosan. In C.albicans, CaCDR1 and CaCDR2 homozygous deletion showed the same level of susceptibility to chitosan as wild type yeast. This suggests that CaCDR1 and CaCDR2 efflux pumps are not required for yeast survival when exposed to chitosan.
Conclusions: Our results showed that neither overexpression nor deletion of CaCDR1 and CaCDR2 efflux pumps affect Ca susceptibility to chitosan, suggesting that drug resistant Ca that overexpresses CaCDR1 or CaCDR2 likely remain susceptible to chitosan. Thus, chitosan may be a useful antifungal agent in cases with drug resistant candidiasis.