Molecular genetic investigations of contaminated contact lens storage cases as reservoirs of Pseudomonas aeruginosa keratitis.

PURPOSE: To elucidate the reservoirs of Pseudomonas aeruginosa keratitis associated with contact lens (CL) wear by using a molecular genotyping method.

METHOD: Ten P. aeruginosa isolates obtained from two young adult patients with infectious keratitis associated with CL wear were studied. These were isolated from corneal specimens, conjunctival swabs, discharges, CL storage cases, and the living environment of the two patients. Species identification was performed with an Oxi/Ferm Tube II system using well-separated colonies on MacConkey and NAC agar plates. We employed molecular genotyping by pulsed-field gel electrophoresis.

RESULTS

We isolated three (one each from a corneal scraping, discharge, and a CL storage case) P. aeruginosa samples from patient 1, and seven (one each from the conjunctival swab, CL storage case, and the patient's fingers, and four from the patient's room) from patient 2. Pseudomonas aeruginosa of environmental origin could not be obtained from the house of patient 1. The genotypes of two P. aeruginosa isolates, from corneal scraping and discharge, were identical to that of the isolate from the CL storage case belonging to patient 1. In patient 2, the isolates from the eye and the CL storage case showed the identical genotype, which was different from those of the environmental isolates.

CONCLUSION

Our results suggest that the causative P. aeruginosa strains in cases of infectious keratitis associated with CL wear originate in contaminated CL storage cases. However, it is still unclear whether the environmental strains in the patients' houses also cause keratitis.