Comparison of culture-positive and culture-negative severe infectious keratitis leading to hospitalization: a tertiary referral center experience

Aim: To compare the predisposing factors, surgical interventions, length of hospital stay (LOHS), and treatment outcomes of culture-positive (CP) versus culture-negative (CN) severe infectious keratitis (IK) resulting in hospitalization in a tertiary referral clinic. Material and Method: We retrospectively reviewed the medical and microbiological records of 287 patients clinically diagnosed with severe keratitis over a 4-year period. Results: Of 287 study participants, 141 (49.1%) had positive CP results. The most common ocular risk factor was a previous ocular surgery (45.6%), and keratoplasty was the first among these ocular surgeries (90.8%). Staphylococcus epidermidis (22.7%) was the most commonly isolated microorganism followed by fungi (17.7%). The initial and final visual acuities did not differ significantly between the CP and CN groups. Major and minor surgical interventions did not significantly differ between the groups (p=0.05). The rates of clear corneal graft in the CP group (p =0.002) were significantly higher than the rates of graft failure in the CN group (p=0.033). No significant difference was noted in the mean LOHS between groups (p=0.66). Logistic regression analyses showed that surgery during admission, S. epidermidis infection, and connective tissue diseases were independent risk factors for a prolonged hospital stay. Conclusion: The initial and final visual acuities, surgical interventions, and LOHS were similar between the CP and CN groups. However, graft failure rates were significantly higher in patients with CN keratitis than in those with CP keratitis.