Regimen and different surfaces interfere with photodynamic therapy on Candida albicans biofilms

Bruna Albuquerque Garcia; Beatriz Helena Dias Panariello; Karina Matthes de Freitas Pontes; Simone Duarte

doi:10.1016/j.mimet.2020.106080

Regimen and different surfaces interfere with photodynamic therapy on Candida albicans biofilms

J Microbiol Methods. 2020 Oct 8:178:106080. doi: 10.1016/j.mimet.2020.106080. Online ahead of print.

Authors

Bruna Albuquerque Garcia¹, Beatriz Helena Dias Panariello², Karina Matthes de Freitas Pontes³, Simone Duarte⁴

Affiliations

¹ Department of Restorative Dentistry, Federal University of Ceara, Fortaleza, Ceara, Brazil. Monsenhor Furtado Street - Rodolfo Teófilo, Fortaleza, CE 60430-355, Brazil. Electronic address: brunaalbuquerque@ufl.edu.
² Department of Cariology, Operative Dentistry and Dental Public Health, Indiana University School of Dentistry, Indianapolis, Indiana, USA. 1121 W. Michigan Street, DS 406; Indianapolis, IN, 46202, USA. Electronic address: bpanari@iu.edu.
³ Department of Restorative Dentistry, Federal University of Ceara, Fortaleza, Ceara, Brazil. Monsenhor Furtado Street - Rodolfo Teófilo, Fortaleza, CE 60430-355, Brazil. Electronic address: karinapontes@ufc.br.
⁴ Department of Cariology, Operative Dentistry and Dental Public Health, Indiana University School of Dentistry, Indianapolis, Indiana, USA. 1121 W. Michigan Street, DS 406; Indianapolis, IN, 46202, USA. Electronic address: siduarte@iu.edu.

PMID: 33039543
DOI: 10.1016/j.mimet.2020.106080

Abstract

The aim of this study is to compare antimicrobial photodynamic therapy (aPDT) against Candida albicans biofilms formed on two different substrates - acrylic resin or bottom of polystyrene plate; and two aPDT application regimens - twice-daily over the course of 48 h or single treatment after 48 h biofilm formation. C. albicans SN425 biofilms cultivated on Roswell Park Memorial Institute medium were incubated for 5 min with toluidine blue O (44 μM) used as a photosensitizer before red light (635 nm; 175.2 J/cm²) exposure for 2 min. As negative control, ultrapure water, and as positive control 0.12% chlorhexidine (CHX) were used. Biofilms were analyzed for colony forming units (CFU) and cells morphology by confocal scanning laser microscopy. Single treatment and twice-daily aPDT on polystyrene plate and single treatment on acrylic resin did not significantly reduce the CFU (p > 0.05); in contrast, twice-daily aPDT on acrylic resin has reduced C. albicans below the detection limit, similarly to CHX treatment. Single aPDT treatment on polystyrene plate and on the resin presented a bulky and homogeneous biofilm predominantly formed by pseudohyphae. In contrast, in the resin group, the biofilm treated twice-daily with aPDT was predominantly formed by yeast cells, whilst pseudohyphae were occasionally visible. In conclusion, biofilms formed on polystyrene plates are more resistant to aPDT than biofilms formed on acrylic resin. Moreover, applying aPDT twice-daily reduces C. albicans biofilm development on acrylic resin and is a better approach against C. albicans biofilms than one single application on the mature biofilm.

Keywords: Biofilm; Candida albicans; Photodynamic therapy; Polymethyl methacrylate; Polystyrene.