The diagnosis of fungal keratitis is normally based on the presence of characteristic clinical signs and a positive result from investigations such as corneal culture, polymerase chain reaction (PCR), and in vivo confocal microscopy (IVCM) [1, 2]. Antifungal treatment may then be initiated, continued, or modified. However, if a positive investigation does not correlate with the clinical signs, the result may be considered a false positive with no change in management. Although the range of positive investigations for fungal keratitis is 25–68% for culture and 37–93% for PCR [1], there is little information as to whether these figures represent true or false positive results. This study aims to contribute to an estimate of the proportion of fungal culture or PCR results that may be false positives.

We searched electronic records from July 2013 to December 2019 for patients investigated for microbial keratitis (MK) who had a positive culture or PCR test for fungus. We defined a false positive result as a case in which fungus was identified, with a result considered by the laboratory to be significant, which resolved with no antifungal prescription (e.g., natamycin, chlorhexidine, amphotericin, or voriconazole). The clinical records of these cases were reviewed. The methodology for culture and PCR has been described previously [1].

Log in or create a free account to read this content

Gain free access to this article, as well as selected content from this journal and more on nature.com

Access through your institution

or

Sign in or create an account
Continue with Google
Continue with ORCiD