Pseudomonas aeruginosa corneal ulcer isolates distinguished using the arbitrarily primed PCR DNA fingerprinting method.

Infection of the eye by Pseudomonas aeruginosa can result in corneal inflammation (keratitis) and ulceration, and permanent decrease in vision if not successfully treated. We tested for diversity among P. aeruginosa strains from corneal ulcers by the sensitive and efficient 'RAPD' (for 'random amplified polymorphic DNA') fingerprinting method. This method uses single oligonucleotides of arbitrarily chosen sequence as primers in low-stringency PCR amplification, and results in strain-specific arrays of DNA fragments. Tests of 20 independent P. aeruginosa corneal ulcer isolates yielded 19 different arrays of products with each of three arbitrary primers, indicating that all but two of the strains differed from one another. Additional isolates from three patients (infected eye, contact lens or eye drops) yielded fragment patterns that were identical to those of the original isolate in each case. Thus, our results demonstrate considerable diversity among P. aeruginosa corneal ulcer isolates, and suggest that just one clone may predominate in typical infections.