Disinfection Efficacy Testing of a Triple Disinfectant System in an Investigational Multi-Purpose Solution Challenged against the Five Bacterial and Fungal Compendial Organisms

Abstract

Purpose : Contact lens (CL) disinfection is critical for the prevention of microbial keratitis (MK) associated with contact lens wear. An investigational multi-purpose solution was designed as a low concentration, triple disinfectant system containing polyaminopropyl biguanide (PAPB), polyquaternium-1 (PQ-1), and alexidine. An evaluation of the investigational MPS was performed to determine the efficacy against the five ISO/FDA organisms, with and without the incorporation of organic soil. The organic soil was added with the organism preparation to further challenge the antimicrobial activity of the triple disinfectant system.

Methods : Testing was performed using Staphylococcus aureus (Sa), Pseudomonas aeruginosa (Pa), Serratia marcescens (Sm), Candida albicans (Ca), and Fusarium solani (Fs), prepared with and without organic soil, to achieve a final concentration from 1.0x10⁵ to 1.0x10⁶ colony forming units (cfu)/ml.

The test solution (10 ml) was dispensed into conical tubes and inoculated with each challenge organism (with or without organic soil). After 4 hours of disinfection, each test solution was neutralized with Dey-Engley Broth (DEB), plated in triplicate, and incubated. Additionally, an inoculum control (IC) was prepared in a suitable diluent to determine the initial concentration of each challenge organism.

Plates were enumerated for the recovery of organisms and log reduction values (LRV) were calculated, based on the mean log recovery of the IC. Three lots of the investigational MPS were tested and the mean LRV determined.

Results : The mean LRV for the bacterial organisms (Sa, Pa, and Sm) without organic soil were 4.7, 4.6, and 4.8, and with the incorporation of organic soil were 4.7, 4.6, and 4.7, respectively. The fungal organisms (Ca and Fs) without organic soil showed mean log reduction values of 3.4 and 4.5 and with the incorporation of organic soil were 4.6 and 4.4, respectively.

Conclusions : The investigational MPS containing the disinfectants PAPB, PQ-1, and alexidine, was efficacious and exceeded the ISO 14729 primary acceptance criteria for each challenge organism. Additionally, there was no decrease to the biocidal activity with the addition of organic soil.
The investigational MPS demonstrated a robust disinfectant system, formulated to reduce the potential risk for MK associated with contact lens wear.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.