Abstract
Purpose
This study investigated the efficacy of pre-conditioning lens cases on bacterial biofilm
formation and removal.
Methods
Silver impregnated (MicroBlock / ProGuard™ & i-Clean) and control storage cases were
pre-conditioned for 24 h with their respective multipurpose solutions (MPDSs). Cases
were then inoculated with 2 ml of 106 CFU/mL of ocular isolates of either P. aeruginosa or S. aureus and incubated for 48 h. Cases were subsequently disinfected (4−6 hours) as per the
manufacturer’s recommended disinfecting time (MRDT) followed by the recommended case
hygiene procedures - recapping wet (MicroBlock / ProGuard™ cases only) or rinse and
air-dry or rinse, tissue-wipe and air dry (mechanical disruption). Surviving bacteria
were enumerated using standard techniques.
Results
Pre-conditioning the MicroBlock / ProGuard™ cases with MPDS significantly reduced
biofilm formation (-1.1 log10 CFU, p < 0.01 for P. aeruginosa & -1.3 log10, p < 0.001, CFU for S. aureus) compared to the i-Clean lens cases. Maintaining the MicroBlock / ProGuard™ lens
cases wet after the MRDT resulted in partial removal of bacterial biofilms (-2.9 log10 CFU, p < 0.001 for P. aeruginosa and -2.6 log10 CFU, p < 0.001 for S. aureus). Air-drying of all three types of lens storage cases after MRDT significantly reduced
the bacterial biofilm (-5.4 log10 CFU, p < 0.001 for P. aeruginosa and -3.5 log10 CFU, p < 0.001 for S. aureus). Mechanical disruption produced the greatest reduction in the levels of bacterial
biofilm in all 3 types of lens cases tested (-6.8 log10 CFU, p < 0.001 for P. aeruginosa and -4.5 log10 CFU, p < 0.001 for S. aureus). Synergi MPDS was significantly better than AQuify MPDS in removing bacterial biofilm
from all 3 lens case types for case hygiene treatments with an air-drying step.
Conclusion
Pre-conditioning of silver-impregnated ProGuard™ lens cases inhibited initial bacterial
biofilm formation. Synergi MPDS was more effective than AQuify MPDS in removing bacterial
biofilm in silver impregnated cases and tissue-wiping significantly improved biofilm
removal.
Keywords
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Article info
Publication history
Published online: November 23, 2019
Accepted:
November 11,
2019
Received in revised form:
November 11,
2019
Received:
July 26,
2019
Identification
Copyright
© 2019 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
