|Lattif, Ali Abdul|
Submitted to: Antimicrobial Agents and Chemotherapy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2007
Publication Date: 11/12/2007
Citation: Imamura, Y., Chandra, J., Mukherjee, P.K., Lattif, A., Szczotka-Flynn, L.B., Pearlman, E., Lass, J.H., O Donnell, K., Ghannoum, M.A. 2007. Fusarium and Candida albicans biofilms on soft contact lenses: model development, influence of lens type and susceptibility to lens care solutions. Antimicrobial Agents and Chemotherapy. 52:171-182. Interpretive Summary: Eye infections caused by species of the filamentous fungus Fusarium and the yeast Candida albicans often result in significant blindness, requiring emergency corneal transplants to restore sight. During the past two years, there has been a significant increase in outbreaks of contact lens-associated corneal infections caused by primarily by Fusarium species, especially among patients using MoistureLoc contact lens care solution. The ability of these fungi to colonize contact lenses and lens cases has been postulated to have played a role in these outbreaks. To test this hypothesis, we developed and validated a protocol for studying contact lens colonization by these pathogenic fungi. Results of these studies show that these fungi could colonize all of the diverse contact lenses tested. One of the most important findings from this study was that fungal colonies were considerably more resistant to the disinfectants in the MositureLoc and MultiPlus contact lens solutions than individual cells separate from the colonies. This finding suggests that the gel-like matrix within which the fungal colonies are embedded protected them from the contact lens solution disinfectants, thereby contributing to the recent outbreaks of contact lens-associated Fusarium infections of the eye. These results should be of considerable interest and benefit the public health community, and the 33 million plus contact users within the US, in that they help emphasize the importance of following precisely the contact lens solution manufacturer’s recommendations for safe contact lens and lens case care. In addition, the results also highlight the need to DNA type the Fusarium species used experimentally so that the results of independent studies can be compared directly.
Technical Abstract: Fungal keratitis is commonly caused by Fusarium species, while cases of Candida-associated keratitis are less frequent. Recent outbreaks of Fusarium keratitis were associated with contact lens wear and 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 the current 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 form biofilms on all types of lenses tested, and that 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 ISO guidelines to test disinfectants) failed to form a biofilm. Furthermore, using the developed in vitro biofilm model we showed that phylogenetically diverse planktonic fusaria and C. albicans were susceptible to MoistureLoc and MultiPlus solutions. However, Fusarium biofilms exhibited reduced susceptibility against these solutions in a strain- and time-dependent manner, suggesting a possible role for biofilm in the recent outbreaks of Fusarium keratitis. This in vitro model should help provide a better understanding of the biology and antifungal resistance of lens-related fungal keratitis.