Comparative Analysis of Cotton- and Flocked-Swab-Based Culture Methods in Bacterial Keratitis

Purpose: To compare the diagnostic performance of flocked-swab and cotton-swab culture methods in patients with bacterial keratitis.Methods: Twentytwo patients diagnosed with bacterial keratitis between May 2024 and August 2025 were included. Corneal specimens were collected using both cotton and flocked swabs. The cotton-swab samples were directly inoculated onto blood, chocolate, and MacConkey agar plates. The flocked-swab specimens were first incubated for 24 h in brain heart infusion broth before plating onto the same media.Results: The flocked-swab method detected Streptococcus spp., Klebsiella pneumoniae, and Escherichia coli, which were not detected by the cotton-swab method. Causative organisms were isolated in 7 patients (31.8%) using the cotton-swab method and in 16 patients (72.7%) using the flocked-swab method, which demonstrated a significantly higher positivity rate (p = 0.0039). The two methods showed concordant results in 59.1% of cases, with Cohen’s κ = 0.298, indicating fair agreement. All nine discordant cases were negative using the cotton-swab method but positive using the flocked-swab method (p = 0.0039). The median time to positivity was 44.5 hours for the cotton swabs and 24.5 hours for the flocked swabs; the shorter trend was not statistically significant (p = 0.216).Conclusions: Compared to cotton swabs, the flocked-swab culture method detected additional organisms, achieved a significantly higher positivity rate, and yielded a shorter time to positivity. Flocked-swab culture may serve as a clinically useful alternative for the microbiological diagnosis of bacterial keratitis when standard culture methods are unavailable.