To determine whether cytotoxic and invasive Pseudomonas aeruginosa strains differentially influence clinical presentation, outcomes, or therapeutic response in bacterial keratitis.
Pseudomonas aeruginosa isolates from the National Eye Institute–funded Steroids for Corneal Ulcers Trial were subtyped as cytotoxic or invasive strains. The main outcome measure compared between the 2 subtypes was change in visual acuity at 3 months using Huber robust regression, adjusting for topical corticosteroid treatment.
Of 101 confirmed P aeruginosa isolates from the Steroids for Corneal Ulcers Trial, 74 had a classically cytotoxic or invasive genotype. While corneal ulcers caused by genotypically invasive P aeruginosa strains were associated at presentation with significantly better visual acuity than corneal ulcers caused by genotypically cytotoxic P aeruginosa strains when adjusting for the effect of ulcer location (P = .008), invasive ulcers had improved significantly less than cytotoxic ulcers at 3 months (0.35; 95% CI, 0.04-0.66 logMAR; P = .03 [3.5-line difference]). Compared with topical moxifloxacin alone, adjunctive treatment with topical corticosteroids was associated with significantly more improvement in visual acuity in the invasive subgroup (P = .04) but was associated with less improvement in visual acuity in the cytotoxic subgroup (P = .07).
Rational profiling of differentially expressed virulence determinants (eg, cytotoxicity and invasiveness for P aeruginosa) could be used as a tool for decision making in the management of infections to optimize outcomes.