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Effect of Hygiene Procedures on Lens Case Contamination with Povidone-Iodine or Multipurpose Disinfecting Solutions
Masahiro Nakagawa, Ritsue Nakagawa1, Mark D P Willcox2
1Ophtecs Corporation, Kobe, Hyogo, Japan.
Significance:
A multipurpose disinfecting solution (MPDS), which contains povidone-iodine (PI) as a disinfectant, has high disinfecting efficacy not only on planktonic bacterium but also on the case biofilms. The addition of case hygiene practice removed more bacteria from cases than MPDS alone.
Purpose:
This study compared the ability of two MPDSs, one containing PI and another containing polyaminopropyl biguanide and polyquaternium, to reduce bacterial numbers in solution or adhered to the cases following case hygiene procedures.
Methods:
Bacterial strains (Delftia acidovorans, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Serratia marcescens, Staphylococcus aureus, and Staphylococcus epidermidis) were exposed to the MPDSs for the recommended disinfection times, and the viable number evaluated according to ISO 14729. Cases were inoculated with bacterial strains and incubated for 24 hours to allow for biofilm formation. Cases were disinfected with both disinfecting solutions for 4 hours and rinsed, followed by recapping or air-drying, or tissue-wiping and air-drying for 18 hours. The number of survivors was counted using standard culture techniques.
Results:
Both products exceeded the recommended 3-log reduction against planktonic bacteria. Regarding biofilm, after rinsing and recapping wet, the numbers of D. acidovorans (mean difference [95% confidence interval] log10 colony-forming units per case, -2.9 [0.8 to -4.6], P < .01), P. aeruginosa (-2.0 [0.5 to -3.1], P < .01), S. marcescens (-1.7 [0.8 to -3.5], P < .05), and S. epidermidis (-2.1 [0.6 to -3.5], P < .05) in PI cases were significantly lower than in the dual-disinfectant MPDS storage cases. After air-drying, the PI storage cases had significantly lower numbers of S. maltophilia (-2.6 [0.6 to -4.0], P < .01), D. acidovorans (-1.6 [0.7 to -3.3], P < .05), and S. aureus (-1.6 [0.7 to -3.1], P < .05). The addition of tissue-wiping reduced the bacterial numbers in the MPDS storage cases to levels in the PI storage cases.
Conclusions:
Contact lens users should be recommended to tissue-wipe and air-dry their lens storage cases after disinfection with regular MPDS.
Insights
Povidone-iodine (PI) multipurpose disinfecting solutions (MPDS) effectively reduce planktonic bacteria and case biofilms. Adding case hygiene practices like tissue-wiping and air-drying further enhances bacterial removal for contact lens users.
Area of Science:
- Ophthalmology
- Microbiology
- Infectious Diseases
Background:
- Multipurpose disinfecting solutions (MPDS) are crucial for contact lens hygiene.
- Povidone-iodine (PI) based MPDS demonstrate efficacy against planktonic bacteria and biofilms.
- The role of additional case hygiene practices in enhancing disinfection efficacy requires further investigation.
Purpose of the Study:
- To compare the efficacy of two MPDS formulations in reducing bacterial load in solution and adhered to contact lens cases.
- To evaluate the impact of case hygiene procedures on the antimicrobial effectiveness of MPDS.
Main Methods:
- Bacterial strains were exposed to PI-based MPDS and a dual-disinfectant MPDS.
- Biofilm formation was induced on cases, followed by disinfection and various post-disinfection procedures (rinsing, air-drying, tissue-wiping).
- Viable bacterial counts were determined using standard culture techniques and ISO 14729.
Main Results:
- Both MPDS formulations achieved the recommended 3-log reduction against planktonic bacteria.
- PI-based MPDS demonstrated superior biofilm reduction compared to the dual-disinfectant MPDS after rinsing and wet storage.
- Air-drying after PI-based MPDS disinfection significantly reduced specific bacterial biofilms, and tissue-wiping further enhanced bacterial removal for both MPDS types.
Conclusions:
- PI-based MPDS are highly effective against planktonic bacteria and biofilms.
- Incorporating case hygiene practices, specifically tissue-wiping and air-drying, significantly improves the removal of bacteria from contact lens cases.
- Contact lens wearers should be advised to perform these hygiene steps to minimize microbial contamination.
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