Abstract
Purpose:
This study was performed to evaluate the biocidal activity of Multi-Purpose Solutions (MPS) against Pseudomonas aeruginosa mixed with fungal organisms. This testing was performed to understand how effective MPS are against a multi-organism challenge, which may better simulate polymicrobial contamination reported for contact lens storage cases.
Methods:
Stand-alone biocidal testing was used with modifications to ISO Standard 14729. Organisms used in this study were not the standard 5 ISO 14729 organisms, but rather mixtures of 6 separate preparations that included P. aeruginosa and one of 6 different fungal organisms. The organisms mixed with P. aeruginosa were: Candida albicans, Candida tropicalis, Fusarium solani, Fusarium oxysporum, Aspergillus brasiliensis, and Aspergillus fumigatus. The mixed challenge inoculum was prepared at the concentration of ~5.0X105 and resuspended in DPBST with the incorporation of 10% organic soil to provide a greater challenge. The mixed inoculum were then used to challenge the MPS. The time points evaluated were 4 and 6 hours for each of the solutions. Each was plated out with Trypticase Soy Agar, and results were recorded in log reductions.
Results:
The results varied for the MPS tested. Fungal organisms were recovered more than P. aeruginosa, as expected. Each solution was assessed at the 4 and 6 hour time points. The recovery for the 4 hour time points ranged from 0.2 log reduction to >4.6 log reduction (no microbial recovery observed), and the 6 hour time point ranged from 0.0 log reduction to >4.6 log reductions (no microbial recovery observed).
Conclusions:
The results show that MPS have a broad range of in vitro antimicrobial activity against the various P. aeruginosa and fungal mixtures. Since environmentally sourced contaminants are frequently mixtures of microorganisms, these results could demonstrate MPS performance that reflects actual use conditions. Further study is warranted to assess the microbiological and clinical significance.
Keywords: 573 keratitis •
664 pseudomonas •
530 fungal disease