Growth kinetics of candida biofilm on medical polymers: a long-term in vitro study

Area of Science:

• Biomaterials Science
• Microbiology
• Medical Device Engineering

Background:

• Current in vitro models for medical polymer biofilm formation are limited to short observation periods (2 hours to 12 days).
• Long-term polymicrobial biofilm development on medical devices is a significant clinical challenge.

Purpose of the Study:

• To develop and validate a novel in vitro model for generating and monitoring long-term polymicrobial biofilms on thermoplastic medical-grade silicone (TPS) and polyurethane (TPU).
• To investigate the growth kinetics and architecture of biofilms formed by Candida albicans and Streptococcus salivarius on these polymers.

Main Methods:

• Polymicrobial biofilms of Candida albicans and Streptococcus salivarius were established on TPS and TPU in RPMI agar at 37°C for 28 days, with continuous nutrient supply and microbial inoculation.
• Biofilm growth kinetics were monitored using image analysis software to quantify surface coverage.
• Biofilm architecture was analyzed using scanning electron microscopy (SEM), and microbial infiltration was assessed via crystal violet staining and microscopy.

Main Results:

• A stable, living Candida biofilm was generated on both TPS and TPU for over 140 days, with a minimum of 10% surface coverage.
• Initial biofilm coverage reached up to 80%, with detachment mitigated by adding planktonic microbes.
• SEM confirmed a three-dimensional biofilm structure with dimorphic Candida growth; microbial infiltration was observed in TPU but not TPS.

Conclusions:

• The developed in vitro model effectively mimics in vivo biofilm formation on medical polymers.
• This model allows for continuous monitoring of living biofilm kinetics over extended periods.
• The findings provide a valuable tool for studying biofilm development on medical devices and testing anti-biofilm strategies.