[Bacterial keratitis in patients with and without contact lens anamnesis]

The study shows differences between contact lens wearers and patients without history of contact lenses regarding the spectrum of etiological agents in bacterial keratitis. Based on microbiological analysis, there are given recommendations for an optimal initial antibiotic treatment in both groups.

From 1989 to 1997 smears, scrapings and corneal biopsies were taken from 218 patients with bacterial keratitis. The causing pathogens were isolated on directly inoculated culture media and identified by staining and microscopy. The resistance pattern of a total of 275 germs was analysed for different antibiotics.

The most frequently isolated germs were Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus spp., Propionibacterium acnes and Pseudomonas aeruginosa. Whereas sensitive gram-positive germs were predominating in contact lens wearers as well as in non-contact lens wearers, multiresistant gram-negative germs could nearly exclusively be isolated from contact lens wearers. Frequently administered antibiotics like aminoglycosides and quinolones are effective in infections caused by Staphylococcus spp., but increasing resistance could be seen to Streptococcus spp. In this case, erythromycin is very sensitive. Gram-negative germs like Pseudomonas aeruginosa are sensitive to quinolones and some aminoglycosides (e.g. tobramycin).

In contact lens wearers, more aggressive germs have to be considered than in non-contact lens wearers. In such cases, frequently administered antibiotics like amino-glycosides are not effective. To cover problematic gram-negative germs we recommend the application of quinolones alternating with erythromycin. The latter one is more effective than quinolones and aminoglycosides in case of Streptococcus spp. co-involvement.