Improving polymerase chain reaction diagnostic rates for herpes simplex keratitis: results of a pilot study

BackgroundLaboratory confirmation is crucial for diagnosis and management of herpes simplex virus (HSV) keratitis. However, the sensitivity of polymerase chain reaction (PCR) in keratitis is low (25%) compared with that of mucocutaneous disease (75%). We developed an educational intervention aimed at improving the diagnostic yield of PCR. MethodsThe medical records of keratitis cases seen at the emergency department of a London tertiary ophthalmic referral hospital over two distinct periods, before and after an educational program on swab technique, were reviewed retrospectively. ResultsA total of 252 HSV cases were included. Increases in the laboratory-confirmed diagnosis of HSV-1 were observed, in both first presentations (11.1%-57.7%) and recurrent cases (20%-57.6%). The rate of positive HSV-1 PCR in eyes with an epithelial defect increased from 19% pre-intervention to 62% post intervention. Notably, 3% were positive for varicella zoster virus DNA, and there was a single case of Acanthamoeba keratitis. ConclusionOur results suggest that, with proper swabbing technique, PCR may be more sensitive than previously reported.