FusariumandCandida albicansBiofilms on Soft Contact Lenses: Model Development, Influence of Lens Type, and Susceptibility to Lens Care Solutions

Abstract

Fungal keratitis is commonly caused by Fusarium species and less commonly by Candida species. Recent outbreaks of Fusarium keratitis were associated with contact lens wear and with ReNu with MoistureLoc contact lens care solution, and biofilm formation on contact lens/lens cases was proposed to play a role in this outbreak. However, no in vitro model for contact lens-associated fungal biofilm has been developed. In this study, we developed and characterized in vitro models of biofilm formation on various soft contact lenses using three species of Fusarium and Candida albicans. The contact lenses tested were etafilcon A, galyfilcon A, lotrafilcon A, balafilcon A, alphafilcon A, and polymacon. Our results showed that clinical isolates of Fusarium and C. albicans formed biofilms on all types of lenses tested and that the biofilm architecture varied with the lens type. Moreover, differences in hyphal content and architecture were found between the biofilms formed by these fungi. We also found that two recently isolated keratitis-associated fusaria formed robust biofilms, while the reference ATCC 36031 strain (recommended by the International Organization for Standardization guidelines for testing of disinfectants) failed to form biofilm. Furthermore, using the developed in vitro biofilm model, we showed that phylogenetically diverse planktonic fusaria and Candida were susceptible to MoistureLoc and MultiPlus. However, Fusarium biofilms exhibited reduced susceptibility against these solutions in a species-and time-dependent manner. This in vitro model should provide a better understanding of the biology and pathogenesis of lens-related fungal keratitis.

Widespread Occurrence of Diverse Human Pathogenic Types of the Fungus Fusarium Detected in Plumbing Drains

“…This hypothesis is further supported by the fact that Fusarium has been recovered in many surveys of water systems, including surveys of municipal water system pipe sections (11) and from a hospital survey sampling plumbing fixtures (2). It has also been demonstrated experimentally that fusaria, particularly members of the FSSC and FOSC, can attach to and form biofilms on contact lenses and polyvinyl chloride pipe (14,25,32,51).…”

Biosurfactants and Bioemulsifiers Biomedical and Related Applications – Present Status and Future Potentials

“…Almost all kind of surfaces are suitable to be colonized by biofilms (Donlan & Costerton, 2002). Biomedical devices are not the exception, biofilms are often found on the surface of urinary catheters (Stickler, 2008), central venous catheters (Petrelli et al, 2006), heart valves (Litzler et al, 2007), voice prostheses (Buijssen et al, 2007), contact lenses (Imamura et al, 2008), hip prostheses (Dempsey et al, 2007) and intrauterine devices (Chassot et al, 2008). Current biofilm preventive strategies are essentially aimed at coating medical surfaces with antimicrobial agents, a process not always successful (Basak et al, 2009;von Eiff et al, 2005).…”

Veterinary Fusarioses within the United States

“…Similar to other medically important fusaria (28), F. oxysporum clonal lineage ST33 is common in plumbing systems and appears to be responsible for the majority of mycoses in human and other animals caused by members of the FOSC (17,29), as well as a pseudoepidemic associated with bronchoscopy specimens at a San Antonio, TX hospital in 1997 and 1998 (30). Phylogenetically diverse fusaria are known to colonize plumbing systems via biofilms (16,(31)(32)(33), and this may explain their near exclusivity in the contact lens solution-associated keratitis outbreaks in the United States, Singapore, and Hong Kong (34,35). Our finding that Fusarium redolens was associated with the granuloma of a cat in California to our knowledge represents only the second report of this soilborne fungus associated with a mycotic infection.…”