Comparison of Culture Results between Specimens from Corneal Scraping with Microhomogenization and Corneal Swab in Moderate and Severe Bacterial Corneal Ulcers

Microbiol Spectr. 2023 Mar 21;11(2):e0356522. doi: 10.1128/spectrum.03565-22. Online ahead of print.

Abstract

The purpose of this study was to compare the bacterial culture results from corneal infiltrate specimens collected using two different methods, corneal scraping followed by microhomogenization and corneal swab. This is a comparative crosssectional study, with 18 participants undergoing corneal specimen collection using each of the 2 sampling techniques. The results from the scraping and swab methods were separated and then compared using data analysis. The proportion of Gram stain results that matched the culture results for the scraping-microhomogenization technique was 6/13 (46.2%), and the proportion of Gram stain results that matched the culture results for the swab technique was 5/13 (38.5%) (McNemar test P value, 1.000; P > 0.05). The proportion of positive cultures obtained using the scraping-microhomogenization technique was 13/18 (72.2%), and the proportion of positive cultures obtained using the swab technique was 9/18 (50%) (McNemar test P value, 0.219; P > 0.05). The Kappa suitability test value for comparison of the scraping-microhomogenization technique to the corneal swab was 0.333. The specimens collected by corneal scraping followed by microhomogenization had a higher positive bacterial culture rate than those collected by corneal swab, but the results were not statistically significant. IMPORTANCE This study aimed to compare the culture results between scraping specimens with microhomogenization and corneal smears in patients with moderate to severe bacterial corneal ulcers. This study could be a guideline for treating bacterial corneal ulcers.

Keywords: bacterial cultures; corneal swab; microhomogenization; scraping.