Cme review: polymerase chain reaction diagnostics for posterior segment disease

Performance of Metagenomic Next-Generation Sequencing of Cell-Free DNA From Vitreous and Aqueous Humor for Diagnoses of Intraocular Infections

BACKGROUND

Delayed diagnosis and improper therapy for intraocular infections usually result in poor prognosis. Due to limitations of conventional culture and polymerase chain reaction methods, most causative pathogens cannot be identified from vitreous humor (VH) or aqueous humor (AH) samples with limited volume.

METHODS

Patients with suspected intraocular infections were enrolled from January 2019 to August 2021. Metagenomic next-generation sequencing (mNGS) was used to detected causative pathogens.

RESULTS

This multicenter prospective study enrolled 488 patients, from whom VH (152) and AH (336) samples were respectively collected and analyzed using mNGS of cell-free DNA (cfDNA). Taking final comprehensive clinical diagnosis as the gold standard, there were 39 patients with indefinite final diagnoses, whereas 288 and 161 patients were diagnosed as definite infectious and noninfectious diseases, respectively. Based on clinical adjudication, the sensitivity (92.2%) and total coincidence rate (81.3%) of mNGS using VH samples were slightly higher than those of mNGS using AH samples (85.4% and 75.4%, respectively).

CONCLUSIONS

Using mNGS of cfDNA, an era with clinical experience for more rapid, independent, and impartial diagnosis of bacterial and other intraocular infections can be expected.

Bilateral herpes zoster ophthalmicus in an immunocompetent patient

INTRODUCTION

Bilateral herpes zoster ophthalmicus (HZO) is rare. We report a case of an immunocompetent patient with nonsimultaneous attacks of HZO in both eyes.

CASE DESCRIPTION

A 71-year-old female patient complained of blurred vision in the left eye for 1 week, which was treated with topical antiglaucomatous drugs due to elevated intraocular pressure. She denied any systemic diseases, but HZO had manifested as a rash with a crust over the right forehead skin 3 months earlier. Slit-lamp examination revealed localized corneal edema with keratin precipitates and mild anterior chamber reaction. Suspecting corneal endotheliitis, we performed aqueous tapping for detecting viral DNA, including cytomegalovirus, herpes simplex virus, and varicella zoster virus (VZV) DNA, through polymerase chain reaction (PCR) testing, but the PCR results were negative for all viruses. The endotheliitis resolved well after treatment with topical prednisolone acetate. However, the patient's blurred vision recurred in the left eye 2 months later. A dendritiform lesion on the left cornea was detected, and corneal scraping for PCR testing revealed VZV DNA. The lesion disappeared with antiviral treatment.

CONCLUSIONS

Bilateral HZO is uncommon, particularly in immunocompetent patients. When in doubt, physicians should perform tests such as PCR testing to help establish a definite diagnosis.

Polymerase chain reaction confirmed mycobacterium tuberculosis intermediate uveitis - analysis of 22 eyes of 14 cases from a tertiary care centre in South India: a retrospective study

Background

To report the role of Polymerase Chain Reaction in confirming the diagnosis of presumed Mycobacterium Tuberculosis (MTB) Intermediate Uveitis.

Method

Retrospective analysis of 22 eyes of 14 cases of presumed tubercular intermediate uveitis wherein intraocular fluid was tested for MTB DNA by Nested & Real-time PCR, based on clinical suspicion of tubercular aetiology. QuantiFERON TB gold test and High-Resolution CT Chest were done. Patients were treated with anti-tubercular therapy with oral steroids & immunomodulators. In the study, eleven were male (79%) and three female (21%). The median age was 34 years. Nested PCR for both IS 6110 & MPB 64 was positive in 64% of the cases, IS 6110 positive in 23% and MPB 64 positive in 15%. Real-time PCR was positive in 48% of the cases. Vision improved in 33% of cases, maintained in 57%, and worsened in 10% of cases.

Conclusion

Presumed Tubercular intermediate uveitis can be confirmed by PCR of intraocular fluids. Anti-tubercular therapy with immunosuppression can improve vision and prevent recurrences in such cases.

Infectious Uveitis in Horses and New Insights in Its Leptospiral Biofilm-Related Pathogenesis

Uveitis is a sight-threatening eye disease in equids known worldwide that leads to considerable pain and suffering. By far the most common type of uveitis in Germany and neighboring countries is classical equine recurrent uveitis (ERU), which is caused by chronic intraocular leptospiral infection and is the main cause of infectious uveitis in horses. Other infectious causes are extremely rare and are usually clinically distinguishable from ERU. ERU can be treated very effectively by vitreous cavity lavage (vitrectomy). For proper indications of this demanding surgery, it is necessary to differentiate ERU from other types of uveitis in which vitrectomy is not helpful. This can be conducted on the basis of anamnesis in combination with ophthalmologic findings and by aqueous humor examination. During vitrectomy, vitreous material is obtained. These vitreous samples have historically been used for numerous etiologic studies. In this way, a chronic intraocular leptospiral infection has been shown to be the cause of typical ERU and, among other findings, ERU has also been recognized as a biofilm infection, providing new insights into the pathogenesis of ERU and explaining some thus far unexplainable phenomena of ERU. ERU may not only have transmissible aspects to some types of uveitis in humans but may also serve as a model for a spontaneously occurring biofilm infection. Vitreous material obtained during therapeutically indicated vitrectomy can be used for further studies on in vivo biofilm formation, biofilm composition and possible therapeutic approaches.

Endophthalmitis after cataract surgery: an update on recent advances

PURPOSE OF REVIEW

Prevention and management of postcataract endophthalmitis remain quite relevant for anterior segment and vitreoretinal surgeons. Although the Endophthalmitis Vitrectomy Study, published in 1996, remains the only level 1 evidence for the management of postcataract endophthalmitis, recent advances have resulted in an evolution of practice patterns. The aim of this review is to summarize the literature regarding postcataract endophthalmitis with a focus on the last 18 months.

RECENT FINDINGS

The IRIS registry indicates the rates of endophthalmitis are decreasing in the United States, and the outcomes appear to be improving. Intracameral moxifloxacin has become more widely accepted and intracameral vancomycin has been shown to be associated with retinal vasculitis. The role of systemic antibiotics and vitrectomy is unclear and practice patterns vary widely.

SUMMARY

Although practice patterns vary, prevention and treatment of endophthalmitis after cataract surgery continues to improve. More uniform guidelines regarding surgical and medical therapy are necessary but the standard of prompt referral to a vitreoretinal specialist for immediate intravitreal antibiotics remains the most important intervention in the management of postcataract endophthalmitis.

Prognostic Utility of Whole-Genome Sequencing and Polymerase Chain Reaction Tests of Ocular Fluids in Postprocedural Endophthalmitis

PURPOSE

To associate detection of potential pathogen DNA in endophthalmitis with clinical outcomes.

DESIGN

Prospective cohort study.

METHODS

Patients in whom endophthalmitis was diagnosed following an intraocular procedure were recruited. Clinical outcome data from baseline, week-1, month-1, and month-3 visits were collected. Intraocular biopsy samples were cultured by standard methods. Quantitative polymerase chain reaction (qPCR) was performed for specific pathogens and whole-genome sequencing (WGS).

RESULTS

A total of 50 patients (mean age 72 years old; 52% male) were enrolled. Twenty-four cases were culture-positive and 26 were culture-negative. WGS identified the cultured organism in 76% of culture-positive cases and identified potential pathogens in 33% of culture-negative cases. Month-1 and -3 visual acuities did not vary by pathogen-positive versus pathogen-negative cases as detected by either culture or WGS. Visual outcomes of Staphylococcus epidermidis endophthalmitis were no different than those of pathogen-negative cases, whereas the patients infected with other pathogens showed worse outcome. Higher baseline bacterial DNA loads of bacteria other than those of S epidermidis detected by WGS were associated with worse month-1 and -3 visual acuity, whereas the S epidermidis loads did not appear to influence outcomes. Torque teno virus (TTV) and Merkel cell polyomavirus (MCV) were detected by qPCR in 49% and 19% of cases, respectively. Presence of TTV at presentation was associated with a higher rate of secondary pars plana vitrectomy (P = .009) and retinal detachment (P = .022).

CONCLUSIONS

The presence and higher load of bacteria other than S epidermidis detected by WGS or DNA from TTV by qPCR in ocular fluids is associated with worse outcomes in post-procedure endophthalmitis.

Usefulness of aqueous and vitreous humor analysis in infectious uveitis

OBJECTIVE

To evaluate the role of intraocular fluid analysis as a diagnostic aid for uveitis.

METHODS

Twenty-eight samples (27 patients including 3 HIV-infected patients) with active (n=24) or non-active (n=4) uveitis were submitted to aqueous (AH; n=12) or vitreous humor (VH) analysis (n=16). All samples were analyzed by quantitative PCR for herpes simplex virus (HSV), varicella zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr virus (EBV) and Toxoplasma gondii.

RESULTS

The positivity of the PCR in AH was 41.7% (5/12), with 50% (2/4) in immunocompetent and 67% (2/3) in HIV+ patients. The positivity of the PCR in VH was 31.2% (5/16), with 13% (1/8) in immunocompetent and 50% (4/8) in immunosuppressed HIV negative patients. The analysis was a determinant in the diagnostic definition in 58% of HA and 50% of VH.

CONCLUSION

Even in posterior uveitis, initial AH analysis may be helpful. A careful formulation of possible clinical diagnosis seems to increase the chance of intraocular sample analysis being meaningful.

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

BACKGROUND

Polymerase chain reaction (PCR) analysis is an important tool in the diagnosis of infectious uveitis. A retrospective, interventional study of PCR analysis of ocular fluid in suspected infectious uveitis cases between January 2014 to July 2016 was done. Nested, real-time and broad range PCR was performed for detection of the genome of Mycobacterium tuberculosis, herpes virus family, Chikungunya virus, Toxoplasma gondii, fungus, eubacterium and propionibacterium acne.

RESULTS

Total of 100 cases included, mean age was 39.2 ± 15.4 years. Uveitis was unilateral in 82% and granulomatous in 40%. Mean visual acuity at the initial visit and final visit was 0.73 logMar and 0.63 logMar respectively. PCR analysis confirmed the clinical diagnosis in 70.1% patients. The sensitivity, specificity, positive predictive value and negative predictive value of PCR analysis was 90.2%, 93.9%, 93.9% and 90.2% respectively. The quantitative value of real-time M. tb. Positive PCR ranged from 32c/ml to 2722 c/ml.

CONCLUSIONS

PCR assay is an accurate technique with high sensitivity and specificity to diagnose the DNA genome in infectious uveitis.

Comparison of two multiplex PCR assays for the detection of Listeria spp. and Listeria monocytogenes in biological samples

Introduction: The aim of the study was to optimise and compare two multiplex PCR assays for the detection of Listeria spp. and Listeria monocytogenes in biological samples including the liver, brain, and blood. Material and Methods: Three strains of L. monocytogenes and single strains of each of the species: L. ivanovii, L. innocua, L. grayi, L. welshimeri, and L. seeligeri were used. Additionally, five other species of bacterium were used to evaluate the specificity of the tests. Results: Specific amplification products were obtained for both multiplex PCR assays, which confirmed the tested strains as Listeria spp. and L. monocytogenes, respectively. Isolates of other species did not yield PCR products. Conclusion: Both multiplex PCR assays proved to be significantly sensitive and highly-specific methods for the detection of Listeria strains.

Aqueous humor polymerase chain reaction in uveitis - utility and safety

Background

To study the value and safety of aqueous humor polymerase chain reaction (PCR) analysis for Herpes simplex, varicella zoster, cytomegalovirus, Epstein-Barr virus and Toxoplasma gondii in patients with uveitis.

Methods

Records of 45 consecutive patients with anterior and posterior uveitis who underwent AC paracentesis with PCR were reviewed. The main outcome measure was frequency of PCR positivity. Secondary outcomes were alteration of treatment, safety of paracentesis, and correlation of keratitic precipitates with PCR positivity,

Results

The overall PCR positivity was 48.9 % (22/45). Therapy was changed because of the PCR results in 14/45 patients (37.7 %). One patient experienced a paracentesis related complication (1/45, 2.2 %) without long-term sequelae.

Conclusion

Aqueous PCR altered the diagnosis and treatment in over a third of our patients and was relatively safe. Aqueous PCR should be considered for uveitis of atypical clinical appearance, recurrent severe uveitis of uncertain etiology, and therapy refractory cases.

The value of routine polymerase chain reaction analysis of intraocular fluid specimens in the diagnosis of infectious posterior uveitis

OBJECTIVE

To assess the value of routine polymerase chain reaction (PCR) analysis on intraocular fluid from patients presenting with a first episode of suspected active infectious posterior uveitis in a population with a high prevalence of human immunodeficiency virus infection.

DESIGN

Retrospective, interventional case series. Participants. 159 consecutive patients presenting at a tertiary care hospital over a five-year period.

METHODS

PCR analysis was performed for cytomegalovirus, varicella zoster virus, herpes simplex virus types 1 and 2, Toxoplasma gondii, and Mycobacterium tuberculosis.

RESULTS

PCR analysis confirmed the initial clinical diagnosis in 55 patients (35%) and altered the initial clinical diagnosis in 36 patients (23%). The clinical diagnosis prior to PCR testing was nonspecific (uncertain) in 51 patients (32%), with PCR providing a definitive final diagnosis in 20 of these patients (39%); necrotizing herpetic retinopathy and ocular toxoplasmosis were particularly difficult to diagnose correctly without the use of PCR analysis.

CONCLUSION

The clinical phenotype alone was unreliable in diagnosing the underlying infectious cause in a quarter of patients in this study. Since the outcome of incorrectly treated infective uveitis can be blinding, PCR analysis of ocular fluids is recommended early in the disease even in resource poor settings.

Laboratory support in the diagnosis of uveitis

Intraocular inflammations are still a diagnostic challenge for ophthalmologists. It is often difficult to make a precise etiological diagnosis in certain situations. Recently, there have been several advances in the investigations of uveitis, which has helped the ophthalmologists a lot in the management of such clinical conditions. A tailored approach to laboratory diagnosis of uveitic cases should be directed by the history, patient's symptoms and signs, and clinical examination. This review summarizes various modalities of laboratory investigations and their role in the diagnosis of uveitis.

Ocular toxoplasmosis II: clinical features, pathology and management

The term, ocular toxoplasmosis, refers to eye disease related to infection with the parasite, Toxoplasma gondii. Recurrent posterior uveitis is the typical form of this disease, characterized by unilateral, necrotizing retinitis with secondary choroiditis, occurring adjacent to a pigmented retinochoroidal scar and associated with retinal vasculitis and vitritis. Multiple atypical presentations are also described, and severe inflammation is observed in immunocompromised patients. Histopathological correlations demonstrate focal coagulative retinal necrosis, and early in the course of the disease, this inflammation is based in the inner retina. For typical ocular toxoplasmosis, a diagnosis is easily made on clinical examination. In atypical cases, ocular fluid testing to detect parasite DNA by polymerase chain reaction or to determine intraocular production of specific antibody may be extremely helpful for establishing aetiology. Given the high seroprevalence of toxoplasmosis in most communities, serological testing for T. gondii antibodies is generally not useful. Despite a lack of published evidence for effectiveness of current therapies, most ophthalmologists elect to treat patients with ocular toxoplasmosis that reduces or threatens to impact vision. Classic therapy consists of oral pyrimethamine and sulfadiazine, plus systemic corticosteroid. Substantial toxicity of this drug combination has spurred interest in alternative antimicrobials, as well as local forms of drug delivery. At this time, however, no therapeutic approach is curative of ocular toxoplasmosis.

Infectious causes of posterior uveitis and panuveitis in Thailand

PURPOSE

To determine the infectious causes of posterior uveitis (PU) and panuveitis (panU) in Thailand.

METHODS

We investigated the infectious causes of uveitis involving the posterior segment of the eye by using real-time polymerase chain reaction (PCR) for cytomegalovirus (CMV), herpes simplex virus (HSV-1, HSV-2), varicella zoster virus and Toxoplasma gondii (T. gondii) DNA in intraocular samples of 80 human immunodeficiency virus (HIV)-negative patients. Additionally, in 61 patients, we performed Goldmann-Witmer coefficient (GWC) analysis for T. gondii.

RESULTS

Twenty-four (30 %) patients with PU and/or panU had a positive PCR result. Overall, CMV was the most frequently identified organism. While CMV was the most common cause of uveitis in the patients on immunosuppressive medications for nonocular disorders, HSV was the most common cause of posterior and panuveitis in the patients not receiving such medication. In 38 PU patients, CMV was the most common detected pathogen. In 42 panU patients, CMV and HSV-2 were the most frequently identified pathogens. Out of 61 paired samples analyzed for T. gondii by GWC analysis, only 1 revealed a positive result. There was no difference in PCR results between aqueous humor and vitreous samples.

CONCLUSIONS

CMV was the most frequently identified infectious organism in posterior and panuveitis of HIV-1-negative Thai patients. Aqueous humor and vitreous samples showed similar diagnostic values in PCR analysis.

Applications of the polymerase chain reaction in clinical ophthalmology

Molecular biology has become a valuable component in many areas of medicine, including ophthalmology. Polymerase chain reaction (PCR) is the most widely used tool. It has proven to be a powerful technique in diagnosis and quantification of microorganisms and antibiotic resistance screening. For a growing number of ophthalmic conditions PCR testing can be conducted. It is therefore important that clinicians be knowledgeable about the indications, strengths, and limitations of the technique. The purpose of this review is to explore the current role of PCR in the diagnosis and management of eye disease.

Polymerase chain reaction analysis of aqueous and vitreous specimens in the diagnosis of posterior segment infectious uveitis

PURPOSE

To assess polymerase chain reaction (PCR) analysis of intraocular fluid as a test for infectious uveitis of the posterior segment in a representative patient population.

DESIGN

Retrospective, interventional case series.

METHODS

One hundred and thirty-three patients with possible infectious chorioretinitis underwent PCR testing of aqueous or vitreous in a university setting. Baseline characteristics predictive of test positivity were identified. Positive and negative predictive values were calculated.

RESULTS

Four hundred and thirty-three PCR tests of 105 aqueous and 38 vitreous specimens (mean, 3.3 tests per patient) identified 77 of the 95 patients with a final clinical diagnosis of infectious uveitis (81%). Herpes simplex virus, varicella zoster virus, and cytomegalovirus PCR analysis were performed in almost all cases, with fewer tests for toxoplasmosis or Epstein-Barr virus. Clinical features associated with positive PCR results were retinal vascular inflammation (P < .001), optic nerve involvement (P = .008), immunocompromised state (P = .039), and extensive retinitis (P = .002). Cases sampled within one week of presentation were more likely to have positive PCR results than those sampled later (P = .071). The predictive value of positive and negative tests was 98.7% and 67.9%, respectively, in this patient group. Alteration in treatment based on PCR and syphilis serologic results led to resolution in 25 of 26 patients after treatment was changed.

CONCLUSIONS

PCR testing is a useful adjunct in the diagnosis of infectious causes of posterior uveitis. Cases with vascular or optic nerve inflammation, extensive retinitis, or immunocompromise are more likely to have positive PCR results and may benefit from PCR testing of aqueous humor.

Advances in the diagnosis and immunotherapy for ocular inflammatory disease

Significant advances in the diagnosis and therapy for uveitis have been made to improve the quality of care for patients with ocular inflammatory diseases. While traditional ophthalmic examination techniques, fluorescein angiography, and optical coherence tomography continue to play a major role in the evaluation of patients with uveitis, the advent of spectral domain optical coherence tomography and fundus autofluorescence into clinical practice provides additional information about disease processes. Polymerase chain reaction and cytokine diagnostics have also continued to play a greater role in the evaluation of patients with inflammatory diseases. The biologic agents, a group of medications that targets cytokines and other soluble mediators of inflammation, have demonstrated promise in targeted immunotherapy for specific uveitic entities. Their ophthalmic indications have continued to expand, improving the therapeutic armentarium of uveitis specialists.