Abstract
Purpose: :
To determine the usefulness of the real PCR assays in the diagnosis of bacterial endophthalmitis in clinically diagnosed infectious cases.
Methods: :
Twenty-three patients with clinically diagnosed infectious endophthalmitis (19 vitreous and 16 aqueous samples) from different sources were included as well as 12 vitreous and 50 aqueous samples from control subjects at a single-university setting. Universal and Gram-specific real time PCR, Gram staining, and culture were carried out. Sensitivity, specificity, predictive values, cycle thresholds (Ct) were determined. Clinical and microbiological data were also assessed.
Results: :
Conventional microbiology (Gram + culture) was able to identify 68% of vitreous samples, 50% of aqueous samples (50%) and 61% of the patients with infectious endophthalmitis. Real time PCR assays was positive in 82% of the vitreous samples and in 100% of the aqueous samples. It was able to diagnose infectious endophthalmitis in 86% of the patients. PCR specificity was 100% for the vitreous and 96% for the aqueous samples. Positive and negative predictive values of PCR were 93% and 95%, respectively, for all samples together. A cutoff value of the Ct was of 37 for universal PCR, 36 for Gram-positive and 35 for Gram-negative bacteria. Gram-positive microorganisms prevailed and visual acuity varied according to the origin of the infection.
Conclusions: :
Real-time PCR is a fast and accurate diagnostic tool for the diagnosis of bacterial endophthalmitis. Being also a quantitative technique, it may allow for a new and unique application: distinction between contamination and infection from the Ct values.
Keywords: endophthalmitis • detection