Diagnosis of tubercular uveitis by quantitative polymerase chain reaction

PURPOSE: To report the use of real-time or quantitative polymerase chain reaction (qPCR) in confirming the diagnosis of tubercular uveitis. METHODS: A qPCR assay using primers targeting the MPB64 gene of Mycobacterium tuberculosis (MTB) was developed. A standard curve for quantification of mycobacterial load was generated. Vitreous fluid samples from patients presumed to have tubercular uveitis were assayed to identify and quantify the mycobacterial load. The amount of the test sample product was interpolated from the standard curve of cycle threshold values generated from known starting copy number of standard MTB DNA. RESULTS: The copies of MTB genomes in the three test samples studied were found to be 7.61 × 10(4), 4.53 × 10(4), and 1.43 × 10(5), respectively. CONCLUSION: qPCR detected and quantified MTB genome from the vitreous fluid of eyes clinically suspected with tubercular uveitis.