Differences In Clinical Behaviour And Outcome Of Bacterial Keratitis Based On Biofilm-Producing Ability

To compare the clinico-microbiological profile and treatment outcomes of bacterial keratitis caused by biofilm-producing (BP) and non-biofilm-producing (BN) organisms.

L V Prasad Eye Institute

This prospective, comparative, non-randomized study was conducted at a tertiary eyecare centre over a period of 18 months. A total of 119 patients with culture-positive bacterial keratitis were enrolled for this study. Biofilm formation of all isolates was assessed using the crystal violet plate (CVP) and XTT reduction assays. Clinical features, antibiotic susceptibility pattern, and outcomes (response to medical therapy, need for surgery, and visual acuity at follow-up) were compared between BP and BN bacteria.

The most common isolate was Staphylococcus aureus (n=38; 31.9%), followed by Staphylococcus epidermidis (n=30; 25.2%) and Pseudomonas aeruginosa (n=20; 16.8%). Biofilm formation was detected in 72.3% (n=86) of isolates. Chloramphenicol resistance was significantly higher in the BP group (72.1%) compared to 45.5% (BN) group (72.1% vs. 45.5%, P=0.006). tThe rates of resistance to multiple drugs (39.5% vs. 33.3%), the response to medical treatment (55.8% vs. 60.6%), and the visual acuity at final follow-up (LogMAR: 1.46±0.94 vs. 1.56±0.93) were of similar trend between the two groups.

Although biofilm-producing organisms showed greater resistance to chloramphenicol, this did not translate into worse clinical outcomes or significant differences in visual improvement when patients received therapy based on the sensitivity patterns.

Biofilm identification of the isolate remains useful for understanding resistance patterns but may not independently predict treatment failure.