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Antifungal activity of amphotericin B and voriconazole against the biofilms and biofilm-dispersed cells of Candida albicans employing a newly developed in vitro pharmacokinetic model.

El-Azizi M, Farag N, Khardori N - Ann. Clin. Microbiol. Antimicrob. (2015)

Bottom Line: Amphotericin B significantly reduced the dispersion of C. albicans cells from the biofilm.Voriconazole showed no significant effect on the viability of C. albicans within the biofilm.This is the first study which investigates the effects of antifungal agents on the biofilm and biofilm-dispersion of C. albicans in an in vitro pharmacokinetic biofilm model.

View Article: PubMed Central - PubMed

Affiliation: German University in Cairo, GUC, Faculty of Pharmacy and Biotechnology, Department of Microbiology, Immunology and Biotechnology, Al-Tagmoa Al-Khamis, New Cairo City, Egypt. mohamed.el-azizi@guc.edu.eg.

ABSTRACT

Background: Candida albicans is a common cause of a variety of superficial and invasive disseminated infections the majority of which are associated with biofilm growth on implanted devices. The aim of the study is to evaluate the activity of amphotericin B and voriconazole against the biofilm and the biofilm-dispersed cells of Candida albicans using a newly developed in vitro pharmacokinetic model which simulates the clinical situation when the antifungal agents are administered intermittently.

Methods: RPMI medium containing 1-5 X 10(6) CFU/ml of C. albicans was continuously delivered to the device at 30 ml/h for 2 hours. The planktonic cells were removed and biofilms on the catheter were kept under continuous flow of RPMI medium at 10 ml/h. Five doses of amphotericin B or voriconazole were delivered to 2, 5 and 10 day-old biofilms at initial concentrations (2 and 3 μg/ml respectively) that were exponentially diluted. Dispersed cells in effluents from the device were counted and the adherent cells on the catheter were evaluated after 48 h of the last dose.

Results: The minimum inhibitory concentration of voriconazole and amphotericin B against the tested isolate was 0.0325 and 0.25 μg/ml respectively. Amphotericin B significantly reduced the dispersion of C. albicans cells from the biofilm. The log10 reduction in the dispersed cells was 2.54-3.54, 2.30-3.55, and 1.94-2.50 following addition of 5 doses of amphotericin B to 2-, 5- and 10-day old biofilms respectively. The number of the viable cells within the biofilm was reduced by 18 (±7.63), 5 and 4% following addition of the 5 doses of amphotericin B to the biofilms respectively. Voriconazole showed no significant effect on the viability of C. albicans within the biofilm.

Conclusion: Both antifungal agents failed to eradicate C. albicans biofilm or stop cell dispersion from them and the resistance progressed with maturation of the biofilm. These findings go along with the need for removal of devices in spite of antifungal therapy in patients with device-related infection. This is the first study which investigates the effects of antifungal agents on the biofilm and biofilm-dispersion of C. albicans in an in vitro pharmacokinetic biofilm model.

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Scanning Electron Micrograph (SEM) shows. (A) the architecture of 24 hours old biofilm of C. albicans on IV vascular catheter following continuous perfusion of the biofilm with fresh medium. (B) The dispersed cells collected from 1 milliliter effluent sample from the biofilm of C. albicans on vascular catheter following 2 day of continuous perfusion by fresh medium. (C) The dispersed cells collected from 1 milliliter effluent sample from 2-day old biofilm of C. albicans on vascular catheter following addition of 2 doses of amphotericin B at 24 hours intervals. (D) The dispersed cells collected from 1 milliliter effluent sample from 2-day old biofilm of C. albicans on vascular catheter following addition of 2 doses of voriconazole at 12 hours intervals. Note that in the biofilm, the cells exist in the yeast and the long tubular hyphal forms while the dispersed cells exist as yeast cell form only.
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Fig5: Scanning Electron Micrograph (SEM) shows. (A) the architecture of 24 hours old biofilm of C. albicans on IV vascular catheter following continuous perfusion of the biofilm with fresh medium. (B) The dispersed cells collected from 1 milliliter effluent sample from the biofilm of C. albicans on vascular catheter following 2 day of continuous perfusion by fresh medium. (C) The dispersed cells collected from 1 milliliter effluent sample from 2-day old biofilm of C. albicans on vascular catheter following addition of 2 doses of amphotericin B at 24 hours intervals. (D) The dispersed cells collected from 1 milliliter effluent sample from 2-day old biofilm of C. albicans on vascular catheter following addition of 2 doses of voriconazole at 12 hours intervals. Note that in the biofilm, the cells exist in the yeast and the long tubular hyphal forms while the dispersed cells exist as yeast cell form only.

Mentions: The scanning electron micrograph (SEM) of 24 hour old biofilm shows the typical pattern of C. albicans cells in the biofilm which consists of yeast form cells (blastospores) and long tubular hyphal cells (Figure 5A). On the other hand, the SEM shows that the dispersed C. albicans cells from the biofilms were in yeast form only (Figure 5B, C and D). The SEM was used, semi quantitatively, to compare the number of dispersed cells of C. albicans following treatment of the biofilms with 2 doses of Amp-B or VCZ compared to drug-free sample. The reduction in the number of dispersed cells was obvious after treating the biofilms of C. albicans with 2 doses of Amp-B compared to VCZ.Figure 5


Antifungal activity of amphotericin B and voriconazole against the biofilms and biofilm-dispersed cells of Candida albicans employing a newly developed in vitro pharmacokinetic model.

El-Azizi M, Farag N, Khardori N - Ann. Clin. Microbiol. Antimicrob. (2015)

Scanning Electron Micrograph (SEM) shows. (A) the architecture of 24 hours old biofilm of C. albicans on IV vascular catheter following continuous perfusion of the biofilm with fresh medium. (B) The dispersed cells collected from 1 milliliter effluent sample from the biofilm of C. albicans on vascular catheter following 2 day of continuous perfusion by fresh medium. (C) The dispersed cells collected from 1 milliliter effluent sample from 2-day old biofilm of C. albicans on vascular catheter following addition of 2 doses of amphotericin B at 24 hours intervals. (D) The dispersed cells collected from 1 milliliter effluent sample from 2-day old biofilm of C. albicans on vascular catheter following addition of 2 doses of voriconazole at 12 hours intervals. Note that in the biofilm, the cells exist in the yeast and the long tubular hyphal forms while the dispersed cells exist as yeast cell form only.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4389768&req=5

Fig5: Scanning Electron Micrograph (SEM) shows. (A) the architecture of 24 hours old biofilm of C. albicans on IV vascular catheter following continuous perfusion of the biofilm with fresh medium. (B) The dispersed cells collected from 1 milliliter effluent sample from the biofilm of C. albicans on vascular catheter following 2 day of continuous perfusion by fresh medium. (C) The dispersed cells collected from 1 milliliter effluent sample from 2-day old biofilm of C. albicans on vascular catheter following addition of 2 doses of amphotericin B at 24 hours intervals. (D) The dispersed cells collected from 1 milliliter effluent sample from 2-day old biofilm of C. albicans on vascular catheter following addition of 2 doses of voriconazole at 12 hours intervals. Note that in the biofilm, the cells exist in the yeast and the long tubular hyphal forms while the dispersed cells exist as yeast cell form only.
Mentions: The scanning electron micrograph (SEM) of 24 hour old biofilm shows the typical pattern of C. albicans cells in the biofilm which consists of yeast form cells (blastospores) and long tubular hyphal cells (Figure 5A). On the other hand, the SEM shows that the dispersed C. albicans cells from the biofilms were in yeast form only (Figure 5B, C and D). The SEM was used, semi quantitatively, to compare the number of dispersed cells of C. albicans following treatment of the biofilms with 2 doses of Amp-B or VCZ compared to drug-free sample. The reduction in the number of dispersed cells was obvious after treating the biofilms of C. albicans with 2 doses of Amp-B compared to VCZ.Figure 5

Bottom Line: Amphotericin B significantly reduced the dispersion of C. albicans cells from the biofilm.Voriconazole showed no significant effect on the viability of C. albicans within the biofilm.This is the first study which investigates the effects of antifungal agents on the biofilm and biofilm-dispersion of C. albicans in an in vitro pharmacokinetic biofilm model.

View Article: PubMed Central - PubMed

Affiliation: German University in Cairo, GUC, Faculty of Pharmacy and Biotechnology, Department of Microbiology, Immunology and Biotechnology, Al-Tagmoa Al-Khamis, New Cairo City, Egypt. mohamed.el-azizi@guc.edu.eg.

ABSTRACT

Background: Candida albicans is a common cause of a variety of superficial and invasive disseminated infections the majority of which are associated with biofilm growth on implanted devices. The aim of the study is to evaluate the activity of amphotericin B and voriconazole against the biofilm and the biofilm-dispersed cells of Candida albicans using a newly developed in vitro pharmacokinetic model which simulates the clinical situation when the antifungal agents are administered intermittently.

Methods: RPMI medium containing 1-5 X 10(6) CFU/ml of C. albicans was continuously delivered to the device at 30 ml/h for 2 hours. The planktonic cells were removed and biofilms on the catheter were kept under continuous flow of RPMI medium at 10 ml/h. Five doses of amphotericin B or voriconazole were delivered to 2, 5 and 10 day-old biofilms at initial concentrations (2 and 3 μg/ml respectively) that were exponentially diluted. Dispersed cells in effluents from the device were counted and the adherent cells on the catheter were evaluated after 48 h of the last dose.

Results: The minimum inhibitory concentration of voriconazole and amphotericin B against the tested isolate was 0.0325 and 0.25 μg/ml respectively. Amphotericin B significantly reduced the dispersion of C. albicans cells from the biofilm. The log10 reduction in the dispersed cells was 2.54-3.54, 2.30-3.55, and 1.94-2.50 following addition of 5 doses of amphotericin B to 2-, 5- and 10-day old biofilms respectively. The number of the viable cells within the biofilm was reduced by 18 (±7.63), 5 and 4% following addition of the 5 doses of amphotericin B to the biofilms respectively. Voriconazole showed no significant effect on the viability of C. albicans within the biofilm.

Conclusion: Both antifungal agents failed to eradicate C. albicans biofilm or stop cell dispersion from them and the resistance progressed with maturation of the biofilm. These findings go along with the need for removal of devices in spite of antifungal therapy in patients with device-related infection. This is the first study which investigates the effects of antifungal agents on the biofilm and biofilm-dispersion of C. albicans in an in vitro pharmacokinetic biofilm model.

Show MeSH
Related in: MedlinePlus