Phenotype of Pseudomonas aeruginosa isolates causing corneal infection between 1997 and 2000

Purpose. To investigate the relationship between functional phenotype of Pseudomonas aeruginosa and the associated human corneal infection. Methods. This was an experimental pilot study of patients presenting With corneal infections at the Jules Stein Eye Institute with presumed P. aeruginosa infection during the period from 12/30/97 to 9/1/00. Thirteen patients were admitted to the study based on positive identification of the causative pathogen as P. aeruginosa and patient consent. Data were collected (including bacterial cultures, lens wear schedule and care, gender and age, completed history questionnaire, clinical photographs). Statistical analysis of possible correlations was performed. Phenotypes of P. aeruginosa were determined, and clinical factors associated with infection were explored. Results. Both invasive and cytotoxic phenotypes of P. aeruginosa were isolated in equal proportion. Cytotoxic strains and invasive strains were found to be associated with patients younger than 50 years of age and older than 50 years of age, respectively. Conclusions. P. aeruginosa remains a significant pathogen in corneal infection, especially during contact lens wear. The age of the patient may influence the phenotype of P. aeruginosa causing infection. Since invasive and cytotoxic strains have different effects on corneal cells, treatment of the infection might require different approaches depending on this phenotype of the causative bacteria.