Research ArticleComparison of the Antimicrobial Efficacy of VariousContact Lens Solutions to Inhibit the Growth ofPseudomonas aeruginosa and Staphylococcus aureus
B Laxmi Narayana Pooja Rao Sevitha Bhat and K Vidyalakshmi
Department of Microbiology Kasturba Medical College Manipal Academy Higher Education MangaloreKarnataka 575001 India
Correspondence should be addressed to Pooja Rao poojakeerthirajmanipaledu
Received 14 March 2018 Accepted 6 May 2018 Published 31 May 2018
Academic Editor Simona Nardoni
Copyright copy 2018 B Laxmi Narayana et al is is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited
Soft contact lenses provide perfect conditions for the breeding of pathogens e study is a prospective experimental studyconducted to know the antimicrobial ability of multipurpose contact lens solution against standard strains of Staphylococcusaureus and Pseudomonas aeruginosa by the stand-alone teste test method is based on the procedures in the ISO 14729 standardprimary stand-alone test ree multipurpose contact lens care solutions commercially available in Mangalore markets namelyBiotrue (Bausch amp Lomb) Opti-Free Replenish (Alcon) and Aquasoft (Stericon Pharma) were tested for its antimicrobial effectin the microbiology lab at Kasturba Medical College Mangalore According to this study the solutions named ldquoBiotruerdquo andldquoAquasoftrdquo met the primary stand-alone and reached the 3log reduction and 5log reduction criteria in the manufacturerrecommended time respectively No conclusion could be drawn for Opti-Free Replenish since the minimum recommendeddisinfection time was overnight whereas it was noted for 6 hr only and it should have been experimented further e ef-fectiveness of multipurpose solutions varies against different bacterial species We have observed that the antimicrobial activity ofdifferent solutions varies with respect to time of incubation and also there was a marked difference in the activity of some solutionsagainst S aureus and P aeruginosa So it is necessary for the contact lens users to store their lenses in solutions for longer duration ofhours It is also recommended to use solutions that clear the ISO 14729 standards for better health conditions of the eye
1 Introduction
Diseases related to the eye are common and frequently seenin clinical practice Soft contact lenses provide perfectconditions for the breeding of pathogens erefore dis-infecting solutions for contact lenses are of utmost im-portance e solutions must be effective in inhibiting thegrowth of pathogens and protecting its users from in-fections [1]
Different pathogens such as Staphylococcus aureusPseudomonas aeruginosa Escherichia coli and other org-anisms commonly cause several eye infections such asbacterial keratitis bacterial conjunctivitis and so on [2]Contact lens solutions may harbour a good number oforganisms due to unhygienic practices by the users climatic
changes especially humidity may become one of the con-tributing factors Excessive contact lens wearers are moreprone to infections and require safety concerns Because ofthe emergence of virulence factors contact lens solutionshave a reduced ability to inhibit their growth [1] Someinvestigations have shown that contact lens-related keratitisis commonly caused by bacteria such as Staphylococcusaureus and Pseudomonas aeruginosa [3] Clinical practi-tioners expose their patients to contact lens solutions byrecommending certain brands for cleaning and disinfectingof their contact lenseserefore clinicians need to be awareof how the solutions are susceptible to the growth of mi-croorganisms [1] Hence this study will help the cliniciansand users to know the efficacy of some of the multipurposecontact lens solutions
HindawiInternational Journal of MicrobiologyVolume 2018 Article ID 5916712 5 pageshttpsdoiorg10115520185916712
2 Materials and Methods
e three multipurpose contact lens solutions (MPS)commercially available in the market were tested for theirantimicrobial effect in the microbiology lab at KMCMangalore It is a prospective experimental comparativestudy Standard strains of Staphylococcus aureus ATCC25923 and Pseudomonas aeruginosa ATCC 27853 were usedfor this test ree multipurpose contact lens care solutionscommercially available in Mangalore markets namelyBiotrue (Bausch amp Lomb) Opti-Free Replenish (Alcon) andAquasoft (Stericon Pharma) were evaluated Normal salinewas used as a control with each batch e products werewell within expiry date and tested according to the manu-facturer labeled instructions for minimum disinfection timee test method was based on the procedures in the ISO14729 standard primary stand-alone test
e antimicrobial efficacy of the regimen was evaluatedaccording to the ISO 14729 standard required for the primarystand-alone test A total of 40 test tubes were used for eval-uation of three solutions plus one control solution (sterilesaline) Two test tubes prepared for each of three solutions weretested for a time interval of 0min 10min 30min 2 hr 4 hrand 6hre 40 test tubes weremarked as solutionA B C andcontrol to prevent biase inoculumpreparedwith 1ml of the05 McFarland standard preparation (15lowast108CFUml) wasadded to 2ml of sterile salineBHI (1 3) and then 1ml of thiswas added to 9ml of sterile saline to give 1 10 e finalprepared suspension in test tubes was made to 2ml consistingof 1900microl of solution A B C or control solution and 100microl ofthe inoculum After this the suspensions were incubated atspecific time intervals and 100microl of each prepared inoculumwas plated onto the MacConkeyrsquos agar plates and incubatedovernight at 35degC in the ambient air and then followed bycolony count and calculation of mean for each suspension pertime interval e determination of the logarithmic reductionof the growth in each solution and the control was calculated bythe following equation
log reduction log10(initial CFU1113870ml)
minus log10(final CFU1113870ml)(1)
e study has received approval from the institutionalethics committee
3 Results
According to the primary stand-alone criteria the tested MPSshould reduce the bacterial colonies by 3log units e pos-itive control had 105 colonies on plating onto the mediaColony counts per solution per time interval for S aureus andP aeruginosa are shown in Tables 1 and 2 e mean loga-rithmic reduction in theminimum recommended disinfectiontime for each of the MPS against the standard S aureus strain(ATCC 25923) and standard P aeruginosa strain (ATCC27853) is shown in Tables 3 and 4 respectively
ere was a great variation in the effects of different MPSon Staphylococcus aureus Biotrue showed good activitytowards S aureus compared with other solutions (Figure 1)
ere was a great variation in the effects of different MPSon Pseudomonas aeruginosa Biotrue showed good activitytowards Pseudomonas compared with other solutions(Figure 2)
Aquasoft passed the ISO 14729 primary stand-alone testafter 4 hr on S aureus but in the case of P aeruginosa it haspassed the test in 6 hr It is to be noted that there is no use ofcontact lens in this experiment hence the action of thesolutions may increase if the contact lens is rubbed or rinsedin the solution On S aureus Aquasoft showed 5log reduc-tion in 4 hr and on P aeruginosa in 6 hr Since the solutionpassed primary stand-alone criteria for both organisms inthe recommended time the requirement for subjecting itto the second test was ruled out Biotrue passed the ISO14729 primary stand-alone test within the manufacturer
Table 1 Colony counts per solution per time interval for Staph-ylococcus aureus
recommended disinfection time (4 hr) S aureus showed 5logreduction after 2 hr whereas P aeruginosa showed after 4 hrNo conclusion could be drawn for Opti-Free Replenish sincethe minimum recommended disinfection time was at least6 hr or overnight whereas it was noted for 6 hr only It showedlog reduction of 175 on S aureus and 126 on P aeruginosaHowever the manufacturer guidelines say that soaking thelens overnight in the solution will show 3log reduction
In the present study (ISO 14729 primary stand-alonetest) Biotrue has shown good antimicrobial activity ascompared to Aquasoft and Opti-Free Replenish In the case
of Biotrue S aureus reached the 3log reduction criteriawithin 2 hr of incubation whereas P aeruginosa reached in4 hr Similar results were found with the Aquasoft solutiontoo the 5log reduction after 4 hr of incubation for S aureusand 6 hr for P aeruginosa
4 Discussion
Contact lenses are easily susceptible to the microbial con-tamination so it is necessary for the contact lens solutions tomeet the ISO 14729 standards for the stand-alone testNoncompliance is one of the factors that commonly lead tothe contact lens-related microbial keratitis [4 5] In thepresent study we tested three dierent contact lens dis-infecting solutions of which Biotrue chemically containspolyaminopropyl biguanide (000013) and poly-quaternium (00001) Opti-Free Replenish containspolyquaterniumPolyquad (0001) and myristamidopropyldimethylamineAldox (00005) and Aquasoft containspolyhexamide Polyhexamide is a disinfectant which carrieshighly charged active sites that can disrupt microbial cellularmembranes by electrostatic interaction which are most ef-fective against a wide range of microorganisms [6 7]Polyquaternium (Polyquad) is a quaternary ammonium-based antimicrobial agent and has antibacterial propertieswhile MAPD showed a wide spectrum of antimicrobialactivity on fungi which is not tested in our study Noprevious study was done with Biotrue (Bausch amp Lomb) forS aureus and P aeruginosa but in one of the studiesconducted by Lever and Roya Renu multipurpose solutionwhich is manufactured by the same manufacturer withsimilar disinfecting agents that is polyaminopropylbiguanide (00001) showed the mean log reduction of gt46for S aureus and gt42 for P aeruginosa and it has achievedthe minimum disinfection criteria more quickly over othertested solutions [8] According to the study done byMohammadinia et al Renu multipurpose solution failed tomeet the ISO stand-alone criteria for Pseudomonas aeru-ginosa [3] In the present study Biotrue showed a signi-cantly higher disinfecting property against S aureus and forP aeruginosa the mean reduction of 5 was seen in S aureus(2 hr) and P aeruginosa (4 hr) respectively
In the present study Opti-Free Replenish which contains0001 polyquaternium (Polyquad) and 00005 Aldoxfailed to meet 3log reduction in 6 hr for S aureus andP aeruginosa In 6 hr S aureus and P aeruginosa have showna mean reduction of 175 and 126 respectively However itshould be noted that the product literature says ldquostore lensesin the closed lens case overnight or at least 6 hoursrdquo One ofthe earlier studies conducted by Marsha et al Opti-FreeExpress which is similar to Opti-Free Replenish with re-spect to disinfectants did not show 3log reduction within 6 hrof incubation where S aureus showed the mean reduction of1252 in 6 hr It is notable that their studies mention for a re-evaluation of the said solution with the secondary regimentest [1] Similar ndings were observed in studies of Lever andRoya too [8]
Aquasoft gained the 3log reduction criteria within 4 hrfor S aureus and 6 hr for P aeruginosa having the log
Log
redu
ctio
n (C
FUm
l)
0
1
2
3
4
5
6
30minutes
Twohours
Fourhours
Six hours10minutes
Time of exposure
BiotrueAquasoftOpti-Free Replenish
Figure 1 Eects of dierent MPS and length of exposure on theconcentration of Staphylococcus aureus
0
1
2
3
4
5
6
Log
redu
ctio
n (C
FUm
l)
30minutes
Twohours
Fourhours
Six hours10minutes
Time of exposure
BiotrueAquasoftOpti-Free Replenish
Figure 2 Eects of dierent MPS and length of exposure on theconcentration of Pseudomonas aeruginosa
International Journal of Microbiology 3
reduction of 5 To the best of our knowledge there are noprevious studies which were conducted with this particularsolution One of the previous studies of Iguban et al usingSolocare where the same polyhexamide was used as thedisinfecting agent also showed good antimicrobial activityagainst P aeruginosa and C albicans [9]
e study conducted by Sakuma et al observed thatnone of their MPS was good enough to remove the or-ganism by the primary stand-alone test alone and patientsshould follow standard instructions carefully including thecleaning and rinsing of contact lenses ere are otherfactors which can eliminate the number of organismsit should be kept in mind that complete antimicrobialactivity can be attained only when there is a combination ofcleaning rinsing and disinfecting the lenses [10] All thestudy solutions reached 3log reduction respectively in themanufacturer recommended time except Opti-Free Re-plenish because it needs to be tested for overnight in-cubation (8 hr) to pass the stand-alone criteria eobserved percentage reduction for Opti-Free Replenish at6 hr for S aureus and P aeruginosa was 981 and 944respectively For 6-hour duration the solution has notpassed the required criteria which is also one of therecommendations according to the literature Probablyovernight incubation would have passed the stand-alonetest which was not done in this study In comparison toldquoUnique Ardquo Opti-Free Replenish which is composed ofPolyquad similar to the former showed less antibacterialactivity while according to the studies conducted byKuzman et al ldquoUnique Ardquo showed excellent activity onS aureus and P aeruginosa [11] According to Hildebrandtet al Opti-Free Replenish with organic load passed thestand-alone test criteria [12] It has reached the 3log re-duction for S aureus and P aeruginosa But in the absenceof organic load it had shown the mean log reduction lessthan 3log and it had failed the stand-alone criteria esefindings are comparable with our results [10]
According to the study of Mohammadinia et al theclinically isolated strains are more resistant than standardstrains [3] For virulent strains MPS takes longer incubationtime for their antimicrobial action so it is recommendedthat further study is required to determine the effectivenessof MPS against such organisms which is one of the limi-tations of our study In the present study we can analyze thatthe solutions which containing polyaminopropyl biguanide(000013) polyquaternium (00001) and polyquaterniumPolyquad (0001) and myristamidopropyl dimethylamineAldox (00005) have good disinfecting property againstS aureus and Pseudomonas aeruginosa but polyhexamide hasless antibacterial activity
5 Conclusion
S aureus and P aeruginosa cause mild to dreadful eyeinfections e findings in our study would help the clini-cians as well as the patients use contact lens multipurposesolutions which follow the guidelines of ISO 14729 standardsas it reduces the chances of acquiring ocular infectionsamong contact lens wearers It is recommended that the
manufacturers also follow the guidelines for the qualitycheck of the solutions e effectiveness of MPS variesagainst different bacterial species Biotrue has shown goodantimicrobial activity and disinfecting property as comparedto Aquasoft and Opti-Free Replenishe current study doesnot evaluate the efficacy of the solutions in clinical isolateshence variations may be observed We have observed thatthe antimicrobial activity of different solutions varies withrespect to time of incubation and also there was a markeddifference in the activity of some solutions against S aureusand P aeruginosa e solution with better disinfectingaction and sufficient hygiene measures is recommended foreveryday use for cleaning by contact lens users
Data Availability
e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
e authors of this study have no financial interest norreceived any financial support from the companies thatmanufacture multipurpose contact lens care solutions
References
[1] M Oberholzer J Raubenheimer M Lyell et al ldquoA com-parison of the ability of three common contact lens solutionswith different constituents to inhibit the growth of Staphy-lococcus aureusrdquo African Vision and Eye Health vol 74 no 1pp 1ndash6 2015
[2] M Amiri M Mohammadinia M Tabatabaee et al ldquoCom-parative efficacies of contact lens disinfecting solutions againstPseudomonas aeruginosardquo Clinical and Experimental Op-tometry vol 94 no 4 pp 348ndash351 2011
[3] M Mohammadinia S Rahmani G Eslami et al ldquoContactlens disinfecting solutions antibacterial efficacy comparisonbetween clinical isolates and the standard ISO ATCC strainsof Pseudomonas aeruginosa and Staphylococcus aureusrdquo Eyevol 26 no 2 pp 327ndash330 2011
[4] D C Chang G B Grant K OrsquoDonnell et al ldquoMultistateoutbreak of Fusarium keratitis associated with use of a contactlens solutionrdquo JAMA vol 296 pp 953ndash963 2006
[5] M Miller D Callahan D McGrath R Manchester andS Norton ldquoCL-160 disinfection efficacy of contact lens caresolutionsrdquoOptometry and Vision Science vol 77 p 264 2000
[6] K Manuj C Gunderson J Troupe and M Huber ldquoEfficacyof contact lens disinfecting solutions against Staphylococcusaureus and Pseudomonas aeruginosardquo Eye and Contact LensScience and Clinical Practice vol 32 no 4 pp 216ndash218 2006
[7] M Demirbilek and E Evren ldquoEfficacy of multipurposecontact lens solutions against ESBL-positive Escherichia coliMRSA and Candida albicans clinical isolatesrdquo Eye andContact Lens Science and Clinical Practice vol 40 no 3pp 157ndash160 2014
[8] A Lever and R Borazjani ldquoComparative antimicrobial effi-cacy of multi-purpose hydrogel lens care solutionsrdquo ContactLens and Anterior Eye vol 24 no 3 pp 94ndash99 2001
[9] E Iguban and J Nanagas ldquoe in vitro anti-microbial activityof multipurpose contact lens solutions against standardstrains of common ocular pathogens the effect of duration
4 International Journal of Microbiology
from first userdquo Journal of Clinical and Experimental Oph-thalmology vol 7 no 3 2016
[10] S Sakuma B Reeh D Dang and M Harris ldquoComparativeefficacies of four soft contact lens disinfection solutionsrdquoInternational Contact Lens Clinic vol 23 no 6 pp 234ndash2411996
[11] T Kuzman M Kutija R Kordic et al ldquoComparative study ofantibacterial an antifungal effects of rigid gas permeablecontact lens disinfecting solutionsrdquo Collegium Antropologi-cum vol 37 no 1 pp 127ndash131 2013
[12] C Hildebrandt D Wagner T Kohlmann et al ldquoIn-vitroanalysis of the microbicidal activity of 6 contact lens caresolutionsrdquo BMC Infectious Diseases vol 12 no 1 2012
e three multipurpose contact lens solutions (MPS)commercially available in the market were tested for theirantimicrobial effect in the microbiology lab at KMCMangalore It is a prospective experimental comparativestudy Standard strains of Staphylococcus aureus ATCC25923 and Pseudomonas aeruginosa ATCC 27853 were usedfor this test ree multipurpose contact lens care solutionscommercially available in Mangalore markets namelyBiotrue (Bausch amp Lomb) Opti-Free Replenish (Alcon) andAquasoft (Stericon Pharma) were evaluated Normal salinewas used as a control with each batch e products werewell within expiry date and tested according to the manu-facturer labeled instructions for minimum disinfection timee test method was based on the procedures in the ISO14729 standard primary stand-alone test
e antimicrobial efficacy of the regimen was evaluatedaccording to the ISO 14729 standard required for the primarystand-alone test A total of 40 test tubes were used for eval-uation of three solutions plus one control solution (sterilesaline) Two test tubes prepared for each of three solutions weretested for a time interval of 0min 10min 30min 2 hr 4 hrand 6hre 40 test tubes weremarked as solutionA B C andcontrol to prevent biase inoculumpreparedwith 1ml of the05 McFarland standard preparation (15lowast108CFUml) wasadded to 2ml of sterile salineBHI (1 3) and then 1ml of thiswas added to 9ml of sterile saline to give 1 10 e finalprepared suspension in test tubes was made to 2ml consistingof 1900microl of solution A B C or control solution and 100microl ofthe inoculum After this the suspensions were incubated atspecific time intervals and 100microl of each prepared inoculumwas plated onto the MacConkeyrsquos agar plates and incubatedovernight at 35degC in the ambient air and then followed bycolony count and calculation of mean for each suspension pertime interval e determination of the logarithmic reductionof the growth in each solution and the control was calculated bythe following equation
log reduction log10(initial CFU1113870ml)
minus log10(final CFU1113870ml)(1)
e study has received approval from the institutionalethics committee
3 Results
According to the primary stand-alone criteria the tested MPSshould reduce the bacterial colonies by 3log units e pos-itive control had 105 colonies on plating onto the mediaColony counts per solution per time interval for S aureus andP aeruginosa are shown in Tables 1 and 2 e mean loga-rithmic reduction in theminimum recommended disinfectiontime for each of the MPS against the standard S aureus strain(ATCC 25923) and standard P aeruginosa strain (ATCC27853) is shown in Tables 3 and 4 respectively
ere was a great variation in the effects of different MPSon Staphylococcus aureus Biotrue showed good activitytowards S aureus compared with other solutions (Figure 1)
ere was a great variation in the effects of different MPSon Pseudomonas aeruginosa Biotrue showed good activitytowards Pseudomonas compared with other solutions(Figure 2)
Aquasoft passed the ISO 14729 primary stand-alone testafter 4 hr on S aureus but in the case of P aeruginosa it haspassed the test in 6 hr It is to be noted that there is no use ofcontact lens in this experiment hence the action of thesolutions may increase if the contact lens is rubbed or rinsedin the solution On S aureus Aquasoft showed 5log reduc-tion in 4 hr and on P aeruginosa in 6 hr Since the solutionpassed primary stand-alone criteria for both organisms inthe recommended time the requirement for subjecting itto the second test was ruled out Biotrue passed the ISO14729 primary stand-alone test within the manufacturer
Table 1 Colony counts per solution per time interval for Staph-ylococcus aureus
recommended disinfection time (4 hr) S aureus showed 5logreduction after 2 hr whereas P aeruginosa showed after 4 hrNo conclusion could be drawn for Opti-Free Replenish sincethe minimum recommended disinfection time was at least6 hr or overnight whereas it was noted for 6 hr only It showedlog reduction of 175 on S aureus and 126 on P aeruginosaHowever the manufacturer guidelines say that soaking thelens overnight in the solution will show 3log reduction
In the present study (ISO 14729 primary stand-alonetest) Biotrue has shown good antimicrobial activity ascompared to Aquasoft and Opti-Free Replenish In the case
of Biotrue S aureus reached the 3log reduction criteriawithin 2 hr of incubation whereas P aeruginosa reached in4 hr Similar results were found with the Aquasoft solutiontoo the 5log reduction after 4 hr of incubation for S aureusand 6 hr for P aeruginosa
4 Discussion
Contact lenses are easily susceptible to the microbial con-tamination so it is necessary for the contact lens solutions tomeet the ISO 14729 standards for the stand-alone testNoncompliance is one of the factors that commonly lead tothe contact lens-related microbial keratitis [4 5] In thepresent study we tested three dierent contact lens dis-infecting solutions of which Biotrue chemically containspolyaminopropyl biguanide (000013) and poly-quaternium (00001) Opti-Free Replenish containspolyquaterniumPolyquad (0001) and myristamidopropyldimethylamineAldox (00005) and Aquasoft containspolyhexamide Polyhexamide is a disinfectant which carrieshighly charged active sites that can disrupt microbial cellularmembranes by electrostatic interaction which are most ef-fective against a wide range of microorganisms [6 7]Polyquaternium (Polyquad) is a quaternary ammonium-based antimicrobial agent and has antibacterial propertieswhile MAPD showed a wide spectrum of antimicrobialactivity on fungi which is not tested in our study Noprevious study was done with Biotrue (Bausch amp Lomb) forS aureus and P aeruginosa but in one of the studiesconducted by Lever and Roya Renu multipurpose solutionwhich is manufactured by the same manufacturer withsimilar disinfecting agents that is polyaminopropylbiguanide (00001) showed the mean log reduction of gt46for S aureus and gt42 for P aeruginosa and it has achievedthe minimum disinfection criteria more quickly over othertested solutions [8] According to the study done byMohammadinia et al Renu multipurpose solution failed tomeet the ISO stand-alone criteria for Pseudomonas aeru-ginosa [3] In the present study Biotrue showed a signi-cantly higher disinfecting property against S aureus and forP aeruginosa the mean reduction of 5 was seen in S aureus(2 hr) and P aeruginosa (4 hr) respectively
In the present study Opti-Free Replenish which contains0001 polyquaternium (Polyquad) and 00005 Aldoxfailed to meet 3log reduction in 6 hr for S aureus andP aeruginosa In 6 hr S aureus and P aeruginosa have showna mean reduction of 175 and 126 respectively However itshould be noted that the product literature says ldquostore lensesin the closed lens case overnight or at least 6 hoursrdquo One ofthe earlier studies conducted by Marsha et al Opti-FreeExpress which is similar to Opti-Free Replenish with re-spect to disinfectants did not show 3log reduction within 6 hrof incubation where S aureus showed the mean reduction of1252 in 6 hr It is notable that their studies mention for a re-evaluation of the said solution with the secondary regimentest [1] Similar ndings were observed in studies of Lever andRoya too [8]
Aquasoft gained the 3log reduction criteria within 4 hrfor S aureus and 6 hr for P aeruginosa having the log
Log
redu
ctio
n (C
FUm
l)
0
1
2
3
4
5
6
30minutes
Twohours
Fourhours
Six hours10minutes
Time of exposure
BiotrueAquasoftOpti-Free Replenish
Figure 1 Eects of dierent MPS and length of exposure on theconcentration of Staphylococcus aureus
0
1
2
3
4
5
6
Log
redu
ctio
n (C
FUm
l)
30minutes
Twohours
Fourhours
Six hours10minutes
Time of exposure
BiotrueAquasoftOpti-Free Replenish
Figure 2 Eects of dierent MPS and length of exposure on theconcentration of Pseudomonas aeruginosa
International Journal of Microbiology 3
reduction of 5 To the best of our knowledge there are noprevious studies which were conducted with this particularsolution One of the previous studies of Iguban et al usingSolocare where the same polyhexamide was used as thedisinfecting agent also showed good antimicrobial activityagainst P aeruginosa and C albicans [9]
e study conducted by Sakuma et al observed thatnone of their MPS was good enough to remove the or-ganism by the primary stand-alone test alone and patientsshould follow standard instructions carefully including thecleaning and rinsing of contact lenses ere are otherfactors which can eliminate the number of organismsit should be kept in mind that complete antimicrobialactivity can be attained only when there is a combination ofcleaning rinsing and disinfecting the lenses [10] All thestudy solutions reached 3log reduction respectively in themanufacturer recommended time except Opti-Free Re-plenish because it needs to be tested for overnight in-cubation (8 hr) to pass the stand-alone criteria eobserved percentage reduction for Opti-Free Replenish at6 hr for S aureus and P aeruginosa was 981 and 944respectively For 6-hour duration the solution has notpassed the required criteria which is also one of therecommendations according to the literature Probablyovernight incubation would have passed the stand-alonetest which was not done in this study In comparison toldquoUnique Ardquo Opti-Free Replenish which is composed ofPolyquad similar to the former showed less antibacterialactivity while according to the studies conducted byKuzman et al ldquoUnique Ardquo showed excellent activity onS aureus and P aeruginosa [11] According to Hildebrandtet al Opti-Free Replenish with organic load passed thestand-alone test criteria [12] It has reached the 3log re-duction for S aureus and P aeruginosa But in the absenceof organic load it had shown the mean log reduction lessthan 3log and it had failed the stand-alone criteria esefindings are comparable with our results [10]
According to the study of Mohammadinia et al theclinically isolated strains are more resistant than standardstrains [3] For virulent strains MPS takes longer incubationtime for their antimicrobial action so it is recommendedthat further study is required to determine the effectivenessof MPS against such organisms which is one of the limi-tations of our study In the present study we can analyze thatthe solutions which containing polyaminopropyl biguanide(000013) polyquaternium (00001) and polyquaterniumPolyquad (0001) and myristamidopropyl dimethylamineAldox (00005) have good disinfecting property againstS aureus and Pseudomonas aeruginosa but polyhexamide hasless antibacterial activity
5 Conclusion
S aureus and P aeruginosa cause mild to dreadful eyeinfections e findings in our study would help the clini-cians as well as the patients use contact lens multipurposesolutions which follow the guidelines of ISO 14729 standardsas it reduces the chances of acquiring ocular infectionsamong contact lens wearers It is recommended that the
manufacturers also follow the guidelines for the qualitycheck of the solutions e effectiveness of MPS variesagainst different bacterial species Biotrue has shown goodantimicrobial activity and disinfecting property as comparedto Aquasoft and Opti-Free Replenishe current study doesnot evaluate the efficacy of the solutions in clinical isolateshence variations may be observed We have observed thatthe antimicrobial activity of different solutions varies withrespect to time of incubation and also there was a markeddifference in the activity of some solutions against S aureusand P aeruginosa e solution with better disinfectingaction and sufficient hygiene measures is recommended foreveryday use for cleaning by contact lens users
Data Availability
e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
e authors of this study have no financial interest norreceived any financial support from the companies thatmanufacture multipurpose contact lens care solutions
References
[1] M Oberholzer J Raubenheimer M Lyell et al ldquoA com-parison of the ability of three common contact lens solutionswith different constituents to inhibit the growth of Staphy-lococcus aureusrdquo African Vision and Eye Health vol 74 no 1pp 1ndash6 2015
[2] M Amiri M Mohammadinia M Tabatabaee et al ldquoCom-parative efficacies of contact lens disinfecting solutions againstPseudomonas aeruginosardquo Clinical and Experimental Op-tometry vol 94 no 4 pp 348ndash351 2011
[3] M Mohammadinia S Rahmani G Eslami et al ldquoContactlens disinfecting solutions antibacterial efficacy comparisonbetween clinical isolates and the standard ISO ATCC strainsof Pseudomonas aeruginosa and Staphylococcus aureusrdquo Eyevol 26 no 2 pp 327ndash330 2011
[4] D C Chang G B Grant K OrsquoDonnell et al ldquoMultistateoutbreak of Fusarium keratitis associated with use of a contactlens solutionrdquo JAMA vol 296 pp 953ndash963 2006
[5] M Miller D Callahan D McGrath R Manchester andS Norton ldquoCL-160 disinfection efficacy of contact lens caresolutionsrdquoOptometry and Vision Science vol 77 p 264 2000
[6] K Manuj C Gunderson J Troupe and M Huber ldquoEfficacyof contact lens disinfecting solutions against Staphylococcusaureus and Pseudomonas aeruginosardquo Eye and Contact LensScience and Clinical Practice vol 32 no 4 pp 216ndash218 2006
[7] M Demirbilek and E Evren ldquoEfficacy of multipurposecontact lens solutions against ESBL-positive Escherichia coliMRSA and Candida albicans clinical isolatesrdquo Eye andContact Lens Science and Clinical Practice vol 40 no 3pp 157ndash160 2014
[8] A Lever and R Borazjani ldquoComparative antimicrobial effi-cacy of multi-purpose hydrogel lens care solutionsrdquo ContactLens and Anterior Eye vol 24 no 3 pp 94ndash99 2001
[9] E Iguban and J Nanagas ldquoe in vitro anti-microbial activityof multipurpose contact lens solutions against standardstrains of common ocular pathogens the effect of duration
4 International Journal of Microbiology
from first userdquo Journal of Clinical and Experimental Oph-thalmology vol 7 no 3 2016
[10] S Sakuma B Reeh D Dang and M Harris ldquoComparativeefficacies of four soft contact lens disinfection solutionsrdquoInternational Contact Lens Clinic vol 23 no 6 pp 234ndash2411996
[11] T Kuzman M Kutija R Kordic et al ldquoComparative study ofantibacterial an antifungal effects of rigid gas permeablecontact lens disinfecting solutionsrdquo Collegium Antropologi-cum vol 37 no 1 pp 127ndash131 2013
[12] C Hildebrandt D Wagner T Kohlmann et al ldquoIn-vitroanalysis of the microbicidal activity of 6 contact lens caresolutionsrdquo BMC Infectious Diseases vol 12 no 1 2012
recommended disinfection time (4 hr) S aureus showed 5logreduction after 2 hr whereas P aeruginosa showed after 4 hrNo conclusion could be drawn for Opti-Free Replenish sincethe minimum recommended disinfection time was at least6 hr or overnight whereas it was noted for 6 hr only It showedlog reduction of 175 on S aureus and 126 on P aeruginosaHowever the manufacturer guidelines say that soaking thelens overnight in the solution will show 3log reduction
In the present study (ISO 14729 primary stand-alonetest) Biotrue has shown good antimicrobial activity ascompared to Aquasoft and Opti-Free Replenish In the case
of Biotrue S aureus reached the 3log reduction criteriawithin 2 hr of incubation whereas P aeruginosa reached in4 hr Similar results were found with the Aquasoft solutiontoo the 5log reduction after 4 hr of incubation for S aureusand 6 hr for P aeruginosa
4 Discussion
Contact lenses are easily susceptible to the microbial con-tamination so it is necessary for the contact lens solutions tomeet the ISO 14729 standards for the stand-alone testNoncompliance is one of the factors that commonly lead tothe contact lens-related microbial keratitis [4 5] In thepresent study we tested three dierent contact lens dis-infecting solutions of which Biotrue chemically containspolyaminopropyl biguanide (000013) and poly-quaternium (00001) Opti-Free Replenish containspolyquaterniumPolyquad (0001) and myristamidopropyldimethylamineAldox (00005) and Aquasoft containspolyhexamide Polyhexamide is a disinfectant which carrieshighly charged active sites that can disrupt microbial cellularmembranes by electrostatic interaction which are most ef-fective against a wide range of microorganisms [6 7]Polyquaternium (Polyquad) is a quaternary ammonium-based antimicrobial agent and has antibacterial propertieswhile MAPD showed a wide spectrum of antimicrobialactivity on fungi which is not tested in our study Noprevious study was done with Biotrue (Bausch amp Lomb) forS aureus and P aeruginosa but in one of the studiesconducted by Lever and Roya Renu multipurpose solutionwhich is manufactured by the same manufacturer withsimilar disinfecting agents that is polyaminopropylbiguanide (00001) showed the mean log reduction of gt46for S aureus and gt42 for P aeruginosa and it has achievedthe minimum disinfection criteria more quickly over othertested solutions [8] According to the study done byMohammadinia et al Renu multipurpose solution failed tomeet the ISO stand-alone criteria for Pseudomonas aeru-ginosa [3] In the present study Biotrue showed a signi-cantly higher disinfecting property against S aureus and forP aeruginosa the mean reduction of 5 was seen in S aureus(2 hr) and P aeruginosa (4 hr) respectively
In the present study Opti-Free Replenish which contains0001 polyquaternium (Polyquad) and 00005 Aldoxfailed to meet 3log reduction in 6 hr for S aureus andP aeruginosa In 6 hr S aureus and P aeruginosa have showna mean reduction of 175 and 126 respectively However itshould be noted that the product literature says ldquostore lensesin the closed lens case overnight or at least 6 hoursrdquo One ofthe earlier studies conducted by Marsha et al Opti-FreeExpress which is similar to Opti-Free Replenish with re-spect to disinfectants did not show 3log reduction within 6 hrof incubation where S aureus showed the mean reduction of1252 in 6 hr It is notable that their studies mention for a re-evaluation of the said solution with the secondary regimentest [1] Similar ndings were observed in studies of Lever andRoya too [8]
Aquasoft gained the 3log reduction criteria within 4 hrfor S aureus and 6 hr for P aeruginosa having the log
Log
redu
ctio
n (C
FUm
l)
0
1
2
3
4
5
6
30minutes
Twohours
Fourhours
Six hours10minutes
Time of exposure
BiotrueAquasoftOpti-Free Replenish
Figure 1 Eects of dierent MPS and length of exposure on theconcentration of Staphylococcus aureus
0
1
2
3
4
5
6
Log
redu
ctio
n (C
FUm
l)
30minutes
Twohours
Fourhours
Six hours10minutes
Time of exposure
BiotrueAquasoftOpti-Free Replenish
Figure 2 Eects of dierent MPS and length of exposure on theconcentration of Pseudomonas aeruginosa
International Journal of Microbiology 3
reduction of 5 To the best of our knowledge there are noprevious studies which were conducted with this particularsolution One of the previous studies of Iguban et al usingSolocare where the same polyhexamide was used as thedisinfecting agent also showed good antimicrobial activityagainst P aeruginosa and C albicans [9]
e study conducted by Sakuma et al observed thatnone of their MPS was good enough to remove the or-ganism by the primary stand-alone test alone and patientsshould follow standard instructions carefully including thecleaning and rinsing of contact lenses ere are otherfactors which can eliminate the number of organismsit should be kept in mind that complete antimicrobialactivity can be attained only when there is a combination ofcleaning rinsing and disinfecting the lenses [10] All thestudy solutions reached 3log reduction respectively in themanufacturer recommended time except Opti-Free Re-plenish because it needs to be tested for overnight in-cubation (8 hr) to pass the stand-alone criteria eobserved percentage reduction for Opti-Free Replenish at6 hr for S aureus and P aeruginosa was 981 and 944respectively For 6-hour duration the solution has notpassed the required criteria which is also one of therecommendations according to the literature Probablyovernight incubation would have passed the stand-alonetest which was not done in this study In comparison toldquoUnique Ardquo Opti-Free Replenish which is composed ofPolyquad similar to the former showed less antibacterialactivity while according to the studies conducted byKuzman et al ldquoUnique Ardquo showed excellent activity onS aureus and P aeruginosa [11] According to Hildebrandtet al Opti-Free Replenish with organic load passed thestand-alone test criteria [12] It has reached the 3log re-duction for S aureus and P aeruginosa But in the absenceof organic load it had shown the mean log reduction lessthan 3log and it had failed the stand-alone criteria esefindings are comparable with our results [10]
According to the study of Mohammadinia et al theclinically isolated strains are more resistant than standardstrains [3] For virulent strains MPS takes longer incubationtime for their antimicrobial action so it is recommendedthat further study is required to determine the effectivenessof MPS against such organisms which is one of the limi-tations of our study In the present study we can analyze thatthe solutions which containing polyaminopropyl biguanide(000013) polyquaternium (00001) and polyquaterniumPolyquad (0001) and myristamidopropyl dimethylamineAldox (00005) have good disinfecting property againstS aureus and Pseudomonas aeruginosa but polyhexamide hasless antibacterial activity
5 Conclusion
S aureus and P aeruginosa cause mild to dreadful eyeinfections e findings in our study would help the clini-cians as well as the patients use contact lens multipurposesolutions which follow the guidelines of ISO 14729 standardsas it reduces the chances of acquiring ocular infectionsamong contact lens wearers It is recommended that the
manufacturers also follow the guidelines for the qualitycheck of the solutions e effectiveness of MPS variesagainst different bacterial species Biotrue has shown goodantimicrobial activity and disinfecting property as comparedto Aquasoft and Opti-Free Replenishe current study doesnot evaluate the efficacy of the solutions in clinical isolateshence variations may be observed We have observed thatthe antimicrobial activity of different solutions varies withrespect to time of incubation and also there was a markeddifference in the activity of some solutions against S aureusand P aeruginosa e solution with better disinfectingaction and sufficient hygiene measures is recommended foreveryday use for cleaning by contact lens users
Data Availability
e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
e authors of this study have no financial interest norreceived any financial support from the companies thatmanufacture multipurpose contact lens care solutions
References
[1] M Oberholzer J Raubenheimer M Lyell et al ldquoA com-parison of the ability of three common contact lens solutionswith different constituents to inhibit the growth of Staphy-lococcus aureusrdquo African Vision and Eye Health vol 74 no 1pp 1ndash6 2015
[2] M Amiri M Mohammadinia M Tabatabaee et al ldquoCom-parative efficacies of contact lens disinfecting solutions againstPseudomonas aeruginosardquo Clinical and Experimental Op-tometry vol 94 no 4 pp 348ndash351 2011
[3] M Mohammadinia S Rahmani G Eslami et al ldquoContactlens disinfecting solutions antibacterial efficacy comparisonbetween clinical isolates and the standard ISO ATCC strainsof Pseudomonas aeruginosa and Staphylococcus aureusrdquo Eyevol 26 no 2 pp 327ndash330 2011
[4] D C Chang G B Grant K OrsquoDonnell et al ldquoMultistateoutbreak of Fusarium keratitis associated with use of a contactlens solutionrdquo JAMA vol 296 pp 953ndash963 2006
[5] M Miller D Callahan D McGrath R Manchester andS Norton ldquoCL-160 disinfection efficacy of contact lens caresolutionsrdquoOptometry and Vision Science vol 77 p 264 2000
[6] K Manuj C Gunderson J Troupe and M Huber ldquoEfficacyof contact lens disinfecting solutions against Staphylococcusaureus and Pseudomonas aeruginosardquo Eye and Contact LensScience and Clinical Practice vol 32 no 4 pp 216ndash218 2006
[7] M Demirbilek and E Evren ldquoEfficacy of multipurposecontact lens solutions against ESBL-positive Escherichia coliMRSA and Candida albicans clinical isolatesrdquo Eye andContact Lens Science and Clinical Practice vol 40 no 3pp 157ndash160 2014
[8] A Lever and R Borazjani ldquoComparative antimicrobial effi-cacy of multi-purpose hydrogel lens care solutionsrdquo ContactLens and Anterior Eye vol 24 no 3 pp 94ndash99 2001
[9] E Iguban and J Nanagas ldquoe in vitro anti-microbial activityof multipurpose contact lens solutions against standardstrains of common ocular pathogens the effect of duration
4 International Journal of Microbiology
from first userdquo Journal of Clinical and Experimental Oph-thalmology vol 7 no 3 2016
[10] S Sakuma B Reeh D Dang and M Harris ldquoComparativeefficacies of four soft contact lens disinfection solutionsrdquoInternational Contact Lens Clinic vol 23 no 6 pp 234ndash2411996
[11] T Kuzman M Kutija R Kordic et al ldquoComparative study ofantibacterial an antifungal effects of rigid gas permeablecontact lens disinfecting solutionsrdquo Collegium Antropologi-cum vol 37 no 1 pp 127ndash131 2013
[12] C Hildebrandt D Wagner T Kohlmann et al ldquoIn-vitroanalysis of the microbicidal activity of 6 contact lens caresolutionsrdquo BMC Infectious Diseases vol 12 no 1 2012
reduction of 5 To the best of our knowledge there are noprevious studies which were conducted with this particularsolution One of the previous studies of Iguban et al usingSolocare where the same polyhexamide was used as thedisinfecting agent also showed good antimicrobial activityagainst P aeruginosa and C albicans [9]
e study conducted by Sakuma et al observed thatnone of their MPS was good enough to remove the or-ganism by the primary stand-alone test alone and patientsshould follow standard instructions carefully including thecleaning and rinsing of contact lenses ere are otherfactors which can eliminate the number of organismsit should be kept in mind that complete antimicrobialactivity can be attained only when there is a combination ofcleaning rinsing and disinfecting the lenses [10] All thestudy solutions reached 3log reduction respectively in themanufacturer recommended time except Opti-Free Re-plenish because it needs to be tested for overnight in-cubation (8 hr) to pass the stand-alone criteria eobserved percentage reduction for Opti-Free Replenish at6 hr for S aureus and P aeruginosa was 981 and 944respectively For 6-hour duration the solution has notpassed the required criteria which is also one of therecommendations according to the literature Probablyovernight incubation would have passed the stand-alonetest which was not done in this study In comparison toldquoUnique Ardquo Opti-Free Replenish which is composed ofPolyquad similar to the former showed less antibacterialactivity while according to the studies conducted byKuzman et al ldquoUnique Ardquo showed excellent activity onS aureus and P aeruginosa [11] According to Hildebrandtet al Opti-Free Replenish with organic load passed thestand-alone test criteria [12] It has reached the 3log re-duction for S aureus and P aeruginosa But in the absenceof organic load it had shown the mean log reduction lessthan 3log and it had failed the stand-alone criteria esefindings are comparable with our results [10]
According to the study of Mohammadinia et al theclinically isolated strains are more resistant than standardstrains [3] For virulent strains MPS takes longer incubationtime for their antimicrobial action so it is recommendedthat further study is required to determine the effectivenessof MPS against such organisms which is one of the limi-tations of our study In the present study we can analyze thatthe solutions which containing polyaminopropyl biguanide(000013) polyquaternium (00001) and polyquaterniumPolyquad (0001) and myristamidopropyl dimethylamineAldox (00005) have good disinfecting property againstS aureus and Pseudomonas aeruginosa but polyhexamide hasless antibacterial activity
5 Conclusion
S aureus and P aeruginosa cause mild to dreadful eyeinfections e findings in our study would help the clini-cians as well as the patients use contact lens multipurposesolutions which follow the guidelines of ISO 14729 standardsas it reduces the chances of acquiring ocular infectionsamong contact lens wearers It is recommended that the
manufacturers also follow the guidelines for the qualitycheck of the solutions e effectiveness of MPS variesagainst different bacterial species Biotrue has shown goodantimicrobial activity and disinfecting property as comparedto Aquasoft and Opti-Free Replenishe current study doesnot evaluate the efficacy of the solutions in clinical isolateshence variations may be observed We have observed thatthe antimicrobial activity of different solutions varies withrespect to time of incubation and also there was a markeddifference in the activity of some solutions against S aureusand P aeruginosa e solution with better disinfectingaction and sufficient hygiene measures is recommended foreveryday use for cleaning by contact lens users
Data Availability
e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
e authors of this study have no financial interest norreceived any financial support from the companies thatmanufacture multipurpose contact lens care solutions
References
[1] M Oberholzer J Raubenheimer M Lyell et al ldquoA com-parison of the ability of three common contact lens solutionswith different constituents to inhibit the growth of Staphy-lococcus aureusrdquo African Vision and Eye Health vol 74 no 1pp 1ndash6 2015
[2] M Amiri M Mohammadinia M Tabatabaee et al ldquoCom-parative efficacies of contact lens disinfecting solutions againstPseudomonas aeruginosardquo Clinical and Experimental Op-tometry vol 94 no 4 pp 348ndash351 2011
[3] M Mohammadinia S Rahmani G Eslami et al ldquoContactlens disinfecting solutions antibacterial efficacy comparisonbetween clinical isolates and the standard ISO ATCC strainsof Pseudomonas aeruginosa and Staphylococcus aureusrdquo Eyevol 26 no 2 pp 327ndash330 2011
[4] D C Chang G B Grant K OrsquoDonnell et al ldquoMultistateoutbreak of Fusarium keratitis associated with use of a contactlens solutionrdquo JAMA vol 296 pp 953ndash963 2006
[5] M Miller D Callahan D McGrath R Manchester andS Norton ldquoCL-160 disinfection efficacy of contact lens caresolutionsrdquoOptometry and Vision Science vol 77 p 264 2000
[6] K Manuj C Gunderson J Troupe and M Huber ldquoEfficacyof contact lens disinfecting solutions against Staphylococcusaureus and Pseudomonas aeruginosardquo Eye and Contact LensScience and Clinical Practice vol 32 no 4 pp 216ndash218 2006
[7] M Demirbilek and E Evren ldquoEfficacy of multipurposecontact lens solutions against ESBL-positive Escherichia coliMRSA and Candida albicans clinical isolatesrdquo Eye andContact Lens Science and Clinical Practice vol 40 no 3pp 157ndash160 2014
[8] A Lever and R Borazjani ldquoComparative antimicrobial effi-cacy of multi-purpose hydrogel lens care solutionsrdquo ContactLens and Anterior Eye vol 24 no 3 pp 94ndash99 2001
[9] E Iguban and J Nanagas ldquoe in vitro anti-microbial activityof multipurpose contact lens solutions against standardstrains of common ocular pathogens the effect of duration
4 International Journal of Microbiology
from first userdquo Journal of Clinical and Experimental Oph-thalmology vol 7 no 3 2016
[10] S Sakuma B Reeh D Dang and M Harris ldquoComparativeefficacies of four soft contact lens disinfection solutionsrdquoInternational Contact Lens Clinic vol 23 no 6 pp 234ndash2411996
[11] T Kuzman M Kutija R Kordic et al ldquoComparative study ofantibacterial an antifungal effects of rigid gas permeablecontact lens disinfecting solutionsrdquo Collegium Antropologi-cum vol 37 no 1 pp 127ndash131 2013
[12] C Hildebrandt D Wagner T Kohlmann et al ldquoIn-vitroanalysis of the microbicidal activity of 6 contact lens caresolutionsrdquo BMC Infectious Diseases vol 12 no 1 2012
from first userdquo Journal of Clinical and Experimental Oph-thalmology vol 7 no 3 2016
[10] S Sakuma B Reeh D Dang and M Harris ldquoComparativeefficacies of four soft contact lens disinfection solutionsrdquoInternational Contact Lens Clinic vol 23 no 6 pp 234ndash2411996
[11] T Kuzman M Kutija R Kordic et al ldquoComparative study ofantibacterial an antifungal effects of rigid gas permeablecontact lens disinfecting solutionsrdquo Collegium Antropologi-cum vol 37 no 1 pp 127ndash131 2013
[12] C Hildebrandt D Wagner T Kohlmann et al ldquoIn-vitroanalysis of the microbicidal activity of 6 contact lens caresolutionsrdquo BMC Infectious Diseases vol 12 no 1 2012
