CL - Efficacy Of CL Solutions - Week -3 Flashcards
What are the 4 testing criteria for CL solutions?
Sterility
Preservative effectiveness
Microbial limits test (tablets/dry products only)
Stability
What test must a CL solution pass to be labelled a “disinfecting solution”?
The Stand Alone Test
What must a MPS (multipurpose solution) pass to meet criteria as both a daily cleaner and disinfectant?
Regimen test
Describe the pathway of testing for CL solution standards (2)
- Does it pass stand alone?
- If not, does it work as a regime?
What microorganisms is a CL solution tasked with dealing with in a stand alone test? (5)
Gram +ve cocci: staph aureus
Gram -ve rod: Serratia meracellens
Gram -ve myo: ps aeruginosa
Yeast: Candida albicans
Fungus: fusarium salani
When is the extent of visibility loss of microorganisms determined in the stand alone test?
At 25%, 50%, 75%, 100% of MRDT (minimum recommended disinfectant time)
What is the pass criteria for a disinfecting CL solution in a stand alone test? (2)
Bacteria reduction by 3 log units (99.9%) within MRDT
Mould and yeast reduction by 1 log unit (90%) within MRDT (+ no increase within 4xMRDT)
What does the Regimen test evaluate?
The antimicrobial efficacy of the entire regimen described in the cleaning instructions insert (i.e. rub, rinse, soak)
What is the pass criteria for the Regimen test (2)?
Bacteria: sum of averages is 5.0log reduction for bacteria with minimum of 1.0 log reduction at MRDT
Moulds and yeast: stasis over MRDT
List 6 disadvantages for the stand alone test
Limited # bacteria tested
No acanthomoeba
No viruses
Lab strains, not clinical isolates
Organic matter (eg mucus, tear debris) not accounted for
Sterile lab env = not the real thing
What is the most common type of microorganism to contaminate a lens solution/ case? What other kinds of microorganisms can contaminate?
Most common = gram +ve bacteria
Gram -ve (also common)
Fungi/yeasts (20-40%)
Acanthomoeba (up to 9%)
What is the main difference between chlorhexidine and polyhexadine?
Polyhexadine has a larger molecular weight than chlorhexidine, which means that it is not able to enter the matrix of soft lens materials and this reduces the likelihood of preservatives reaching the ocular surface
i.e. polyhexadine doesn’t enter the lens b/c of it’s MW
What micororganism persists even after disinfection with chlorhexidine?
s. marcescens
Can acanthomoeba survive in 1-step 3% hydrogen peroxide systems? Explain
yes. Because the neutralisation of the peroxide is too rapid.
What disinfectant is the best at killing microorganisms?
Hydrogen peroxide
What percentage of microorganisms on CLs are lost through rinsing? What about rinsing and rubbing together?
Rinsing: 99%
Rinsing and Rubbing: 99.9%