RT Journal Article SR Electronic T1 PCR and culture for diagnosis of Acanthamoeba keratitis JF British Journal of Ophthalmology JO Br J Ophthalmol FD BMJ Publishing Group Ltd. SP 1302 OP 1306 DO 10.1136/bjophthalmol-2020-316730 VO 105 IS 9 A1 Helene Yera A1 Vichita Ok A1 Fiona Lee Koy Kuet A1 Naima Dahane A1 Frédéric Ariey A1 Lilia Hasseine A1 Pascal Delaunay A1 David Martiano A1 Pierre Marty A1 Jean Louis Bourges YR 2021 UL http://bjo.bmj.com/content/105/9/1302.abstract AB Background/Aims Acanthamoeba keratitis (AK) is a rare but sight-threatening infection. Molecular diagnosis of corneal scraping has improved the diagnosis of AK. Different molecular targets and conditions have been used in diagnosis thus far. In this study, we prospectively compared the performance of five PCR assays on corneal samples for the diagnosis of AK.Methods 1217 corneal scraping samples were obtained from patients, for whom an AK was suspected. Sample processing involved both molecular diagnostics and culture. Acanthamoeba PCR assays detected different regions of the Acanthamoeba nuclear small-subunit rRNA gene: three final point PCR assays using Nelson, ACARNA and JDP1–JDP2 pairs of primers, and two real-time PCR assays using Acant primer-probe. Human DNA and internal control were co-amplified in the real-time PCR assay to ensure scraping quality and the absence of inhibitors. In the absence of a gold standard, the performance of each test was evaluated using latent class analysis. Genotypes of Acanthamoeba isolates were also characterised.Results Estimated prevalence of AK was 1.32%. The sensitivity of Acanthamoeba diagnostic PCRs (73.3% to 86.7%) did not differ significantly from that of culture (66.7%), or according to the target sequence or the technology. Sensitivity could be increased to 93.8% or 100% by combining two or three assays, respectively. PCR specificity (99.3% to 100%) differed between the assays. T4 was the predominant Acanthamoeba genotype (84.6%).Conclusions Culture and a single PCR assay could lead to misdiagnosing AK. A combination of different PCR assays and improved sample quality could increase diagnosis sensitivity.