[Microbiological analysis in contact lens-associated keratits]

Abstract

Introduction: More than 125 million (2 %) people worldwide wear contact lenses (CL). 0.011 - 0.2 % of the wearers develop keratitis per year. The aim of this study was to explore and analyse the spectrum of germs in different microbiological analysis techniques to optimize the strategy of antiobiotic therapy.

Patients and methods: A retrospective study about 65 eyes with CL induced keratitis or corneal ulceration who were treated in our hospital between 2005 - 2010. We analysed and compared the development of best-corrected visual acuity (BCVA) under single and combined antibiotic therapy and microbiological analysis of conjunctiva (CS) and CL and CL-container swabs (CLS).

Results: Of the patients 96.9 % were soft contact lenses wearers. 48.8 % had microbiological findings in the CS, 81.3 % in CLS. 19.6 % (n = 9) coagulase-negative Stapyhlococcus and 17.3 (n = 8) Pseudomonas species were found. Different spectra of germs in CS and CLS were found. Gram-positive bacteria in CS (54.5 %) were dominant, whereas Gram-negative bacteria were dominant in CLS. No significant difference of mean BCVA changes between single (0.09 ± 0.2) and double (0.14 ± 0.29) topical antibiotic therapy (p = 0.16) were seen, but significant differences between the groups of "gentamicin & ofloxacin" (0.2 ± 0.2) and "moxifloxacin & tobramycin" (0.1 ± 0.43) (p < 0.05) were found. No significant differences of BCVA change between patients with positive (0.12 ± 0.23) and negative (0.20 ± 0.37) microbiological results of conjunctival swabs were observed (p = 0.5).

Conclusions: A strong association between keratitis among wearers of soft lenses and typical spectra of germs was found. Different microbiological findings in different swabs, a lack of findings in around 51.2 % of CS combined with the comparable clinical outcomes between sterile and "microbial" disease means the findings from CS are less important. No differences in development of BCVA between single and double antibiotical therapy were found. There was a better outcome of BCVA with ofloxacin with gentamicin compared to newer generation agents. To improve current treatment strategies in future we recommend increasing the microbiological analysis of CL and CL containers.