Abstract
Purpose: :
To determine the genotype distribution among ocular isolates of P. aeruginosa andcompare its adhesion to various contact lens materials
Methods: :
Two genotypes of P. aeruginosa, namely, invasive (exoS) and cytotoxic (exoU) have been reported with variable antibiotic sensitivity. We first determined the genotype distribution among ocular isolates of P. aeruginosa by multiplex PCR. The adhesion of these two genotypes of P. aeruginosa to a conventional hydrogel (etafilconA) and silicone hydrogel contact lenses (balafilcon A; galyfilcon A) was done by viable cell culturing method. Scanning electron microscopy (SEM) of these lenses with and without bacterial adhesion was performed to analyze surface characteristics of lenses.
Results: :
Cytotoxic genotype predominated among our contact lens-related microbial keratitis (CLMK) isolates while invasive genotype was more common in all ocular isolates.Analysis comparing contact lens adhesion between the two genotypes to a conventional hydrogel (etafilconA) and silicone hydrogel contact lenses (balafilcon A; galyfilcon A) found no statistical significant difference. With the same genotype, galyfilcon A had the least bacterial adhesion compared to etafilcon A or balafilcon A (P<0.05). Among silicone hydrogels, balafilcon A had the highest number of attached bacteria. Surface characterization by scanning electron microscopy (SEM) of these lenses showed a prominent difference between surface treated balafilcon A lenses and non-surface treated galyfilcon A and etafilcon A lenses. Bacterial adhesion to the lenses was mostly on the surface of the lenses and not associated with the polymer’s pores.
Conclusions: :
Contact lens material rather than P. aeruginosa genotype may more significantly affect in P. aeruginosa adhesion to contact lens surfaces.
Keywords: contact lens • cornea: basic science