Polymerase chain reaction (PCR) for microbiological diagnostic in infectious keratitis: a clinical study on 16 patients

Background: The identification of the causative pathogen in infectious kera titis is possible in only 60% of the cases. The aim of this study was to sh ow if this number increases by the use of PCR. Patients and methods: In a series of 16 eyes with infectious keratitis corn eal specimems were collected for culture and PCR. Serology (HSV, VZV, and B orrelia) was performed in all eyes, with exception of the 4 eyes presenting an acute form of keratitis, which obviously was bacterial origin. Results: In all 4 cases of acute keratitis the causative pathogen (Pseudomo nas aeruginosa) was detected by both culture and PCR. Of the remaining 12 e yes PCR was capable to identify the causative pathogen in 11 eyes. In 3 eye s herpes simplex virus was detected, in 3 eyes Moraxella catharalis, in 2 e yes Borrelia burgdorferii, in 2 eyes varizella tester virus, and in 1 eye B artonella henselae. Culture was positive in only 2 eyes, infected by Moraxe lla catharalis. Conclusions: PCR is a useful supplement in the microbiological diagnostic o f infectious keratitis, in particular if only a small amount of pathogens a re available (non-acute form) or if the eye has been treated by antibiotics prior to the microbiological diagnostic.