Detection ofToxoplasma gondiiDNA in peripheral blood and aqueous humor of patients with Toxoplasmic active focal necrotizing retinochoroiditis using real-time PCR

Abstract

Purpose: To evaluate the ability of real-time quantitative PCR (qPCR) for detecting Toxoplasma gondii DNA in the peripheral blood and aqueous humor of patients with toxoplasmic active focal necrotizing retinochoroiditis. Methods: Fifty-five patients with infectious uveitis seen from 2009 to 2013 at the Department of Ophthalmology and Visual Sciences of the Federal University of São Paulo were enrolled in this study. Forty-three patients had toxoplasmic active focal necrotizing retinochoroiditis, and the remaining 12 had non-toxoplasmic infectious uveitis and served as controls. qPCR analysis for T. gondii DNA was performed on the patients' peripheral blood and aqueous humor samples. Results:The qPCR was positive for T. gondii DNA in 37.21% (16/43) of the aqueous humor samples and 2.33% (1/43) of the peripheral blood samples; further, 16.27% (7/43) of the patients had positive results in both their blood and aqueous humor samples. Conclusion: qPCR was able to detect T. gondii DNA in patients with toxoplasmic active focal necrotizing retinochoroiditis in the blood as well as the aqueous humor and can help with the diagnosis of the disease.

Outcome of polymerase chain reaction (PCR) analysis in 100 suspected cases of infectious uveitis

“…Studies have shown variable sensitivity ranging from 27 to 85% [2, 19–21]. Reports from Brazil [22] have shown detection of Toxoplasma gondii DNA in an aqueous sample with qPCR in 37.2%, but in our scenario, out of five cases placed for PCR for identification of Toxoplasma gondii , all of them were negative. This poor sensitivity in detection of Toxoplasma gondii in our experience may be due to the inappropriate timing of test as chances of PCR positivity may be higher in early 2 weeks but we at tertiary level are dealing mainly with referred cases with late presentation.…”

Digital droplet polymerase chain reaction analysis of common viruses in the aqueous humour of patients with Posner‐Schlossman syndrome in Chinese population

“…PSS is an elusive disease, and usually the diagnosis of ocular disease relies mainly on history, clinical signs and routine examinations, which typically cannot effectively assist the clinical diagnosis of PSS because of the limited sensitivity and specificity. Recently, it was reported that PSS is related to viral infections, so clear identification of the pathogen is very important before treatment . It is well‐known that the management of infection caused by different viruses, bacteria, fungi or parasites requires different treatments, so accurate pathogen detection in aqueous humour is of great importance for the aetiology of pathogenic PSS.…”

“…Recently, it was reported that PSS is related to viral infections, 4-6 so clear identification of the pathogen is very important before treatment. 17,18 It is well-known that the management of infection caused by different viruses, bacteria, fungi or parasites requires different treatments, so accurate pathogen detection in aqueous humour is of great importance for the aetiology of pathogenic PSS. However, no more than 300 μL of eye fluid can be safely obtained for diagnostic detection, and usually the concentration of pathogenic nucleic acids in aqueous humour is much lower than that in peripheral blood samples, so a highly sensitive detection approach urgently needed.…”

Performance of 2 Polymerization Protocols Targeting Cloned Toxoplasma Parasites

“…Due to the previously mentioned advantages of qPCR over conventional PCR, it seems highly possible that there will be an agreement on real-time PCR assays in the future. In a relatively recent study done by Santos et al, [ 12 ], qPCR was able to diagnose T. gondii in patients with uveitis, and they recorded the reliability of this assay in diagnosing toxoplasmic active focal necrotizing retinochoroiditis. However, such an agreement on the choice of the most suitable sequence to be amplified will be more challenging.…”