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Armin Mohi, Susanne Hauswaldt, Salvatore Grisanti, Martin Rudolf; Effect of preservatives in artificial tears on bacterial growth in a blepharitis setting. Invest. Ophthalmol. Vis. Sci. 2016;57(12):6176.
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© ARVO (1962-2015); The Authors (2016-present)
Blepharitis is a chronic inflammatory disease of the eyelids. Although the etiology is complex and not fully understood, it is general consensus that bacteria and inflammation are a main part of this pathology. A continuous treatment with artificial tears is fundamental treatment strategy. In this study we investigated the potential antimicrobial effect of different preservatives in artificial tears on the bacterial flora of blepharitis patients.
We incubated agar-plates with different bacteria which are commonly found in blepharitis patients (S. aureus; S. epidermidis; C. amycolatum, A. baumannii, P. acnes) to perform an agar diffusion test (Kirby-Bauer testing). We soaked the testing discs with different eye drops. We used commercial artificial tears. One with benzalkonium chloride (BAK) and two with polyhexamethylene biguanide (PHMB) in different concentrations (0,001 vs. 0,0015 mg/ml) as eye drop preservative. We compared this eye drops with a preservative free compound and two different antibiotic eyedrops (Ofloxacin, Gentamicin). In addition we tested PHMB in different concentrations (0,001, 0,01, 0,1, 0,2, 0,3 mg/ml) in the same setting. After 24-48 h (incubation, 37°C) we evaluated the effect of the different compounds on the bacterial growth.
As expected Ofloxacin and Gentamicin showed a good reduction of bacterial growth in all tested bacteria (18-40 mm). The tested preservatives showed a poor reduction of the bacterial growth. The PHMB showed no reduction at all in the used concentrations. The BAK showed a significant reduction on the P. acnes culture. The preservative free eye drop showed no reduction at all.The PHMB alone showed a significant reduction beginning from a concentration of 0,01 mg/ml on Staph. aureus, Staph epidermidis and P. acnes. Beginning from 0,1 mg/ml on Corynebacterium amycolatum and beginning from 0,2 mg/ml on A. baumannii.
The collected data showed no significant reduction of bacterial growth by using PHMB in this low concentration as an eye drop preservative. By using a higher concentration (>0,01 mg/ml) we could see a significant reduction on 3 of the 5 tested bacteria cultures. The BAK showed a good effect on the growth of P. acnes. There could be a positive effect on the bacterial load and the chronic inflammation of blepharitis patients by using a higher concentration of PHMB as a preservative in artificial tears.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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