Rapid point-of-care identification of Aspergillus spp. in microbial keratitis

Rameshkumar Gunasekaran, Abinaya Chandrasekaran, Rajarathinam Karpagam, Sheelagh Duncan, Kevin Dhaliwal, Prajna Lalitha, N. Venkatesh Prajna, Beth Mills*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Importance: There is a requirement to develop and implement rapid and simple point-of-care diagnostics for fungal keratitis (FK).
Objective: Here we evaluate a commercially available lateral flow device (AspLFD) and report on Aspergillus spp. diagnostic accuracy against clinical cases of FK at a tertiary centre in south India from both corneal scrape and minimally invasive swab samples.
Setting: All study participants were recruited at the corneal clinic at Aravind Eye Hospital, Madurai, India during their first presentation to the clinic.
Participants: Participants were eligible if they had a corneal ulcer with suspected bacterial or fungal infection.
Design: This was a prospective diagnostic feasibility study conducted between May 2022 and Jan 2023. During routine diagnostic scraping, a minimally invasive corneal swab, and one additional corneal scrape were collected and transferred to aliquots of sample buffer and analysed by LFD if the patient met the inclusion criteria (n = 198 scrape samples and n = 40 swab samples). Photographs of devices were taken for a non-biased semi-quantitative analysis approach, developed as part of the study. AspLFD results were compared to culture reports (LFD scorers were blinded to culture report at time of scoring).
Main Outcome(s) and Measure(s): Determine sensitivity and specificity of the AspLFD device with corneal samples collected from microbial keratitis patients.
Results: The average age of the 198 participants included in the study analysis was 51, and 126 were male. 35/198 and 17/40 of culture positive samples were Aspergillus spp. Ratiometric analysis results for scrape samples (95% CI): Sensitivity: 0.89 (0.74 – 0.95); Specificity: 0.95 (0.91 – 0.98); Positive Likelihood-Ratio: 18.05 (9.09 – 35.84); Negative Likelihood-Ratio: 0.12 (0.05 – 0.30); and Accuracy: 0.94 (0.90 – 0.97). Ratiometric analysis, for swab samples (95% CI): Sensitivity: 0.94 (0.73 – 1.00); Specificity: 0.83 (0.63 – 0.93); Positive Likelihood-Ratio: 5.41 (2.20 – 13.29); Negative Likelihood-Ratio: 0.07 (0.01 – 0.48); and Accuracy: 0.88 (0.73 – 0.96).
Conclusions and Relevance: Ratiometric analysis of LFDs for the diagnosis of FK demonstrated high diagnostic accuracy in identifying patients with Aspergillus FK direct from corneal scrapes and swabs. This is an important step towards the provision of point-of-care diagnostics for microbial keratitis, and could inform on clinical management strategy.

Original languageEnglish
JournalJAMA ophthalmology
Issue number10
Publication statusPublished - 28 Sept 2023


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