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Effects of contact lens solution disinfectants against filamentous fungi

Yan Xu1, Yi He, Lutan Zhou

  • 1*MD †BD ‡PhD Laboratory of Ocular Pharmacology (YX, GP), Cornea Service (YH), Laboratory of Ocular Microbiology (SS), Henan Eye Institute and Henan Eye Hospital, Department of Ophthalmology, Henan Provincial People's Hospital, Zhengzhou, Henan, China; Department of Optometry, Zhengzhou Railway Vocational and Technical College, Zhengzhou, Henan, China (LZ); Department of Ophthalmology, Zhengzhou Second Hospital, Zhengzhou, Henan, China (CG); and National University Hospital, Yong Loo Lin School of Medicine, National University of Singapore, Republic of Singapore (XW).

Optometry and Vision Science : Official Publication of the American Academy of Optometry
|October 4, 2014
PubMed
Abstract

Insights

Thimerosal demonstrated superior antifungal activity against ocular Fusarium solani and Aspergillus flavus compared to other disinfectants. Current multipurpose disinfectant solution concentrations of PHMB, cetylpyridinium chloride, and chlorhexidine are sublethal for these fungal pathogens.

Area of Science:

  • Ophthalmology
  • Mycology
  • Infectious Diseases

Background:

  • Ocular fungal infections pose a significant threat to vision.
  • Multipurpose disinfectant solutions (MPDSs) are commonly used for contact lens care.
  • The efficacy of disinfectants in MPDSs against ocular pathogens requires thorough evaluation.

Purpose of the Study:

  • To compare the in vitro antifungal activity of four disinfectants: polyhexamethylene biguanide (PHMB), thimerosal, cetylpyridinium chloride, and chlorhexidine.
  • To assess their effectiveness against clinical isolates of Fusarium solani and Aspergillus flavus, common causes of ocular infections.

Main Methods:

  • In vitro antifungal susceptibility testing was performed using the Clinical and Laboratory Standards Institute (CLSI) M38-A broth dilution method.
  • The study evaluated 40 isolates of ocular pathogenic fungi, including 24 F. solani and 16 A. flavus.
  • Minimum inhibitory concentration for 90% of the organisms (MIC90) was determined for each disinfectant.

Main Results:

  • Thimerosal exhibited the lowest MIC90 values, indicating potent activity (0.0313 μg/mL for F. solani, 0.0625 μg/mL for A. flavus).
  • Cetylpyridinium chloride showed moderate activity (2 μg/mL for both species).
  • PHMB (4 μg/mL for F. solani, 16 μg/mL for A. flavus) and chlorhexidine (32 μg/mL for both species) displayed lower antifungal potency.

Conclusions:

  • Thimerosal demonstrated the highest in vitro antifungal activity against ocular F. solani and A. flavus isolates among the tested disinfectants.
  • The concentrations of PHMB, cetylpyridinium chloride, and chlorhexidine commonly found in MPDSs are below levels required to inhibit these fungal pathogens.
  • The choice of disinfectant significantly impacts the overall antimicrobial efficacy of MPDS formulations.

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