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Biocidal efficacy of multipurpose solutions against Gram-negative organisms associated with corneal infiltrative
Denise Callahan1, Christopher Kovacs1, Shawn Lynch1
1Bausch & Lomb Incorporated, Rochester, New York, USA.
Background:
Because corneal infiltrative events (CIEs) may result from bacterial components on contact lenses, which can come from contaminated lens cases, we evaluated the biocidal efficacy of five multipurpose solutions against Gram-negative commonly isolated and CIE-associated organisms.
Methods:
Of the multipurpose solutions tested, one contained polyhexamethylene biguanide (PHMB)/polyquaternium-1 (PQ-1; Bausch & Lomb Incorporated: Biotrue), one contained alexidine dihydrochloride (alexidine)/PQ-1 (AMO: RevitaLens OcuTec) and three contained PQ-1/myristamidopropyl dimethylamine (MAPD; Alcon: Opti-Free PureMoist, PQ-1/MAPD-1; Opti-Free RepleniSH, PQ-1/MAPD-2; Opti-Free Express, PQ-1/MAPD-3). Challenge organisms were CIE-associated Achromobacter xylosoxidans, Delftia acidovorans and Stenotrophomonas maltophilia at manufacturer-recommended durations (stand-alone), in lens cases without lenses (up to seven days) and in lens cases with etafilcon A lenses (up to 30 days).
Results:
In stand-alone testing against CIE-associated organisms, PHMB/PQ-1 and alexidine/PQ-1 were significantly superior versus MAPD-based multipurpose solutions against A. xylosoxidans (all p ≤ 0.01), D. acidovorans (all p ≤ 0.001) and S. maltophilia (all p ≤ 0.05). In lens cases, PHMB/PQ-1 and alexidine/PQ-1 achieved greater than 3-log reductions against all challenge organisms at all times evaluated. PQ-1/MAPD-1 achieved a greater than 3-log reduction against D. acidovorans at 24 hours; PQ-1/MAPD-1 and PQ-1/MAPD-3 achieved greater than 3-log reductions at seven days against all organisms. In lens cases with lenses, PHMB/PQ-1 and alexidine/PQ-1 achieved greater than 3-log reductions against all organisms at all times. PQ-1/MAPD-1 and PQ-1/MAPD-3 achieved greater than 3-log reductions at seven or more days against all organisms. PQ-1/MAPD-2 did not achieve a greater than 3-log reduction at any time; some regrowth was observed.
Conclusions:
PHMB- and alexidine-based multipurpose solutions demonstrated significantly greater biocidal activity compared with PQ-1/MAPD-based agents against Gram-negative organisms commonly isolated and CIE-associated pathogens.
Insights
Polyhexamethylene biguanide (PHMB) and alexidine-based multipurpose solutions show superior efficacy against Gram-negative bacteria linked to contact lens events. These formulations offer enhanced protection compared to polyquaternium-1/myristamidopropyl dimethylamine (PQ-1/MAPD) agents.
Area of Science:
- Ophthalmology
- Microbiology
- Materials Science
Background:
- Corneal infiltrative events (CIEs) can stem from bacteria on contact lenses originating from contaminated cases.
- Evaluating the antimicrobial properties of contact lens solutions is crucial for preventing eye infections.
Purpose of the Study:
- To assess the biocidal effectiveness of five multipurpose solutions against Gram-negative bacteria associated with CIEs.
- To compare the efficacy of solutions containing PHMB/PQ-1 and alexidine/PQ-1 against PQ-1/MAPD-based solutions.
Main Methods:
- Five multipurpose solutions with varying active ingredients (PHMB/PQ-1, alexidine/PQ-1, PQ-1/MAPD) were tested.
- Challenge organisms included Achromobacter xylosoxidans, Delftia acidovorans, and Stenotrophomonas maltophilia.
- Efficacy was evaluated in stand-alone tests, in lens cases without lenses, and in lens cases with lenses over specified durations.
Main Results:
- PHMB/PQ-1 and alexidine/PQ-1 solutions were significantly more effective than PQ-1/MAPD solutions against all tested organisms.
- PHMB/PQ-1 and alexidine/PQ-1 achieved substantial log reductions in microbial load in lens cases, with and without lenses.
- Some PQ-1/MAPD solutions showed limited efficacy, with one exhibiting microbial regrowth.
Conclusions:
- Multipurpose solutions containing PHMB or alexidine demonstrate superior biocidal activity against Gram-negative bacteria implicated in CIEs.
- These findings suggest that PHMB- and alexidine-based solutions may offer better protection against contact lens-related infections.
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