Development and evaluation of a pan-fungal lateral flow device for the rapid identification of pathogen class in microbial keratitis

PurposeTo develop a pan-fungal lateral flow device (LFD); evaluating device performance with samples obtained from ex vivo porcine cornea infection models. MethodsFungal {beta}-glucan (PF1), human CLEC7A/Dectin-1/CLECSF12 protein (Fc Tag; PF2), and fungal melanin (PF3) antibodies were evaluated for binding to clinically relevant fungal and bacterial species (Aspergillus flavus, Fusarium keratoplasticum, Candida albicans, Pseudomonas aeruginosa, Staphylococcus aureus) by immunofluorescence staining. PF1 and PF2 were evaluated in proof-of-concept, in-house LFD strips using cultured pathogens and ex vivo porcine corneal infection samples. The lead antibody (PF1) was validated in a commercially-developed prototype LFD. ResultsPF1 and PF2 discriminated target fungi from bacteria by immunofluorescence microscopy and in-house LFD strips. The lead candidate PF1 demonstrated good sensitivity (0.75) and specificity (0.94) with cultured fungal hyphae. Samples obtained from infected ex vivo cornea by clinically relevant methods confirmed excellent sensitivity (scrapes: 1.00, swabs: 0.94) and specificity (scrapes: 1.00, swabs: 0.83). The commercially-developed PF1-LFD prototype achieved perfect sensitivity (1.00) and specificity (1.00) when detecting and discriminating fungi from non-fungal ex vivo corneal swab samples. ConclusionsFeasibility of pan-fungal LFD application in microbial keratitis diagnosis was demonstrated - using {beta}-glucan as a pan-fungal target and a clinically relevant microbial keratitis ex vivo model. LFDs were able to differentiate fungal from bacterial samples, detect antigen present in corneal swabs, and provide a read-out within 20 minutes. Sensitivity and specificity values are comparable to currently used diagnostic tests. Translational RelevanceEarly discrimination of fungal keratitis cases is important to adapt treatment, and improve patient outcome.