PCR for detection of herpes simplex virus in cerebrospinal fluid: alternative acceptance criteria for diagnostic workup

Comparison of two assays to diagnose herpes simplex virus in patients with central nervous system infections

BACKGROUND

Multiplex PCR panels are frequently used for detecting the diagnosis of central nervous system infection, but have demonstrated lower sensitivity for herpes simplex virus (HSV) compared to targeted PCRs. Providers in our institution frequently order both multiplex (BioFire Meningitis/Encephalitis Panel (MEP)) and targeted HSV PCR (Diasorin Simplexa HSV-1/2 Direct), allowing comparison of assay performance in practice and a unique clinical characterization of patients with concordant positive or discordant results.

METHODS

We retrospectively analyzed all HSV testing performed using the two assays simultaneously in a large multi-center institution between 12/10/2018 and 6/6/2022. We described and compared laboratory, diagnostic and therapeutic data between patients with positive results on both assays with patients with discordant results.

RESULTS

1,387 patients were tested with both assays, of which 25 were positive on at least one assay. Eleven (44%) had discordant results; 9 were targeted-PCR-positive/MEP-negative and 2 were targeted-PCR-negative/MEP-positive. Compared with patients with concordant positive results, discordant targeted PCR-positive/MEP-negative patients had a higher PCR cycle threshold value (i.e., >35) and milder illness characterized by lower CSF WBC counts (4 vs 152; p = 0.032), fewer MRI abnormalities (37.5% vs. 87.5%; p = 0.039), HSV meningoencephalitis as primary discharge diagnosis (33% vs. 100%; p<0.0001) and were more often treated with oral medication or none at all.

CONCLUSIONS

Patients with discordant targeted PCR-positive/MEP-negative results represent a population with milder clinical disease. These findings will help clinicians and laboratorians determine when both targeted HSV and multiplex assays should be performed simultaneously and identify patients for whom a multiplex PCR may suffice, despite lower assay sensitivity.

An Electronic Health Record Intervention to Limit Viral Testing of Cerebrospinal Fluid

Meningitis and encephalitis are neurologic emergencies that require immediate management and current guidelines recommend empiric treatment with broad-spectrum antimicrobials. Cerebrospinal fluid (CSF) testing algorithms are heterogeneous and largely institution-specific, reflecting a lack of consensus on how to effectively identify CSF pathogens while conserving resources and avoiding false positives. Moreover, many lumbar punctures (LPs) performed in the inpatient setting are done for noninfectious workups, such as evaluation for leptomeningeal metastasis. As such, tailoring CSF testing to clinical context has been a focus of multiple prior reports and several healthcare systems have focused on efforts to limit low-yield diagnostic testing when a positive result is unlikely. To curb ordering viral PCRs when pre-test probability is low, some peer institutions have implemented pleocytosis criteria for virus-specific polymerase chain reaction (PCR) tests from CSF. In this report, we retrospectively analyzed the diagnostic testing of CSF from patients who had an LP while admitted to a single, large academic medical center and found that many cases of Herpes Simplex Virus (HSV) meningoencephalitis were diagnosed by non-neurologists. The rate of positive virus-specific PCR tests was very low, and tests were frequently ordered in duplicate with a multiplexed meningitis/encephalitis PCR panel (M/E panel, BioFire, Salt Lake City, UT). We designed and implemented a systems-level intervention to promote a revised stepwise testing algorithm that minimizes unnecessary tests. This intervention led to a significant reduction in the number of low-yield virus-specific PCR tests ordered without implementing a policy of cancelling virus-specific PCRs.

Rational Use of Microbiological Tests in the Diagnosis of Central Nervous System Infections Using Restrictive Criteria: a Retrospective Study

Microbiological testing in general and in the setting of central nervous system (CNS) infection in particular are often excessive, leading to superfluous laboratory work and costs. In this regard, restrictive criteria, named Reller criteria, have been developed to reduce unnecessary CSF herpes simplex virus 1 (HSV-1) PCR testing when suspecting encephalitis.

Screening for Viral Nucleic Acids in the Cerebrospinal Fluid of Dogs With Central Nervous System Inflammation

Central nervous system (CNS) inflammation is a common cause of neurological dysfunction in dogs. Most dogs with CNS inflammation are diagnosed with presumptive autoimmune disease. A smaller number are diagnosed with an infectious etiology. Additionally, at necropsy, a subset of dogs with CNS inflammation do not fit previously described patterns of autoimmune disease and an infectious cause is not readily identifiable. Because viral infection is a common cause of meningoencephalitis in people, we hypothesize that a subset of dogs presented with CNS inflammation have an occult viral infection either as a direct cause of CNS inflammation or a trigger for autoimmunity. The goal of this research was to screen cerebrospinal fluid from a large number dogs with CNS inflammation for occult viral infection. One hundred seventy-two dogs with neurological dysfunction and cerebrospinal fluid (CSF) pleocytosis were identified. Of these, 42 had meningoencephalitis of unknown origin, six had steroid-responsive meningitis-arteritis, one had eosinophilic meningoencephalitis, five had documented infection, 21 had and undetermined diagnosis, and 97 had a diagnosis not consistent with primary inflammatory disease of the CNS (e.g., neoplasia). CSF samples were subsequently screened with broadly reactive PCR for eight viral groups: adenovirus, bunyavirus, coronavirus, enterovirus, flavivirus, herpesvirus, paramyxovirus, and parechovirus. No viral nucleic acids were detected from 168 cases screened for eight viral groups, which does not support occult viral infection as a cause of CNS inflammation in dogs. La Crosse virus (LACV) nucleic acids were detected from four cases in Georgia. Subclinical infection was supported in two of these cases but LACV could not be ruled-out as a cause of infection in the other two cases, suggesting further research is warranted to determine if LACV is an occult cause of CNS inflammation in dogs.

Evaluation of the selection of cerebrospinal fluid testing in suspected meningitis and encephalitis

Diagnostic stewardship interventions can decrease unnecessary antimicrobial therapy and microbiology laboratory resources and costs. This retrospective cross-sectional study evaluated factors associated with inappropriate initial cerebrospinal fluid (CSF) testing in patients with suspected community-acquired meningitis or encephalitis. In 250 patients, 202 (80.8%) and 48 (19.2%) were suspected meningitis and encephalitis, respectively. 207 (82.8%) patients had inappropriate and 43 (17.2%) appropriate testing. Any inappropriate CSF test was greatest in the immunocompromised (IC) group (n = 54, 91.5%), followed by non-IC (n = 109, 80.1%) and HIV (n = 44, 80%). Ordering performed on the general ward was associated with inappropriate CSF test orders (adjOR 2.81, 95% CI [1.08-7.34]). Laboratory fee costs associated with excessive testing was close to $300,000 per year. A stepwise algorithm defining empiric and add on tests according to CSF parameters and patient characteristics could improve CSF test ordering in patients with suspected meningitis or encephalitis.

Diagnosis of Herpes Simplex Virus: Laboratory and Point-of-Care Techniques

Herpes is a widespread viral infection caused by the herpes simplex virus (HSV) that has no permanent cure to date. There are two subtypes, HSV-1 and HSV-2, that are known to cause a variety of symptoms, ranging from acute to chronic. HSV is highly contagious and can be transmitted via any type of physical contact. Additionally, viral shedding can also happen from asymptomatic infections. Thus, early and accurate detection of HSV is needed to prevent the transmission of this infection. Herpes can be diagnosed in two ways, by either detecting the presence of the virus in lesions or the antibodies in the blood. Different detection techniques are available based on both laboratory and point of care (POC) devices. Laboratory techniques include different biochemical assays, microscopy, and nucleic acid amplification. In contrast, POC techniques include microfluidics-based tests that enable on-spot testing. Here, we aim to review the different diagnostic techniques, both laboratory-based and POC, their limits of detection, sensitivity, and specificity, as well as their advantages and disadvantages.

Viral Infections of the Central Nervous System in Children: A Systematic Review

Viral infections of the central nervous system such as meningitis, encephalitis or meningoencephalitis, are important causes of significant morbidities and mortality worldwide. Early diagnosis and prompt treatment will lead to better outcomes, but any delay may results in high fatality with serious neurologic sequelae among survivors. We conducted a systematic review of published literature on the clinical presentation, diagnosis, treatment and complications of viral infections of the central nervous system from 1980 to 2019 on four databases comprising of PubMed, PubMed Central, Google Scholar and Medline to give the current understanding for better patient management. This systematic review demonstrates the management approach of viral infections of the central nervous system in children from the point of clinical presentation, diagnosis, treatment and complications. Definitive treatment remained unknown; however, certain antiviral drugs were proved to be effective. Therefore, prevention through childhood vaccination is the best management option.

Economic Evaluation: Onsite HSV PCR Capabilities for Pediatric Care

Objective:

Herpes simplex virus (HSV) encephalitis has an overall mortality rate of 11%–29% with treatment. Although rare, HSV encephalitis is frequently tested for and empirically treated, especially in the neonatal population. HSV infection can be diagnosed with polymerase chain reaction (PCR) testing, although this frequently requires sending samples to reference laboratories. The inherent delay in results may lead to prolonging empiric treatment and hospital stay, resulting in increased costs. This study investigates whether onsite HSV PCR testing decreases hospitalization duration, acyclovir treatment duration, and financial cost on an institution.

Project design:

This single-center project utilized the IHI model for improvement to evaluate third-party HSV PCR processing versus an implemented onsite PCR-based meningitis–encephalitis panel for HSV central nervous system evaluation. The primary outcome was hospital cost differential with secondary outcomes, including duration of acyclovir administration and time to result.

Results:

We identified 96 children age 0–18 from 2010 to 2016, 74 patients utilizing offsite third-party testing, and 22 patients utilizing onsite. We observed a per-patient cost savings of $428 ($618.43–$190.43, P = 0.029) upon the implementation of onsite testing. The mean duration of acyclovir therapy decreased from 3.7 to 0.26 days per patient (P < 0.001). Time to result decreased from 4.6 to 0.13 days (P < 0.001).

Conclusions:

Acquisition of real-time local HSV PCR capabilities significantly decreased time to result and empiric medication use while significantly reducing hospital costs in a military treatment facility.

Meningoencefalitis por herpes simple: una visión de la infección viral que causa el mayor compromiso cerebral

La inflamación del sistema nervioso central secundaria a la infección por la familia herpesviridae puede generar un compromiso difuso del parénquima encefálico, la cual puede ser fatal en ausencia de un rápido diagnóstico y tratamiento. Objetivo: revisar las diferentes características biológicas, fisiopatológicas, clínicas, terapéuticas y pronóstico de la meningoencefalitis causada por VHS-1 y 2. Materiales y métodos: revisión de la literatura científica (revisión crítica), llevada a cabo mediante las bases de datos Medline y buscadores específicos IMBIOMED, PUBMEDE, SCIENCEDIRECT, SCIELO, con un total de 150 artículos, se priorizaron 67 los cuales fueron leídos a profundidad. Resultados y discusión: debido el neurotropismo del herpes virus simple puede causar neuroinvasividad, neurotoxicidad y latencia en el SNC. Por sus características semiológicas inespecíficas se requiere un estudio exhaustivo para lograr el diagnóstico acertado. Los métodos actuales tales como neuroimágenes y PCR han aportado al esclarecimiento del diagnóstico etiológico de esta patología. La detección temprana de la entidad y la instauración precoz del tratamiento, se asocian con un aumento en la tasa de supervivencia y a una disminución de las secuelas neurológicas. Conclusión: conocer la biología del virus, su comportamiento, las características clínicas y el tratamiento de la entidad es una estrategia eficaz para disminuir secuelas y desenlaces fatales.

Applicability of molecular assays for detection and typing of herpes simplex viruses in encephalitis cases

Herpes simplex viruses (HSVs) cause a latent infection in humans which is mainly associated with characteristic cold sores or fever blisters and genital blisters. Large segments of the world population are suffering from the HSV infection and early diagnosis as well as treatments are needed to avoid further complications. HSV surveillance is very sparse, especially from developing countries including India. The aim of the present study is to develop and evaluate molecular assays for rapid detection and typing of HSV. In the present study, viral DNA was extracted from cerebro-spinal fluid from HSV suspected encephalitis patients. The conventional multiplex PCR for HSV-1 and HSV-2 was optimized and their comparative analysis was done with Real-Time qPCR for detection and typing of HSV. Out of 137 clinical samples, eleven samples (8.03%) were diagnosed as HSV positive by Real-Time qPCR while ten (7.3%) by conventional multiplex PCR which were further typed as subtyping HSV-1 (nine) and HSV-2 (two). Real-Time qPCR is highly sensitive and able to detect 9.4 × 10¹ to 3.1 × 10⁶ copies/ml of HSV DNA. Conventional PCR was found to be having 99.21% specificity with 100% sensitivity. The positive predictive value was 90.91% whereas negative predictive value was 100%. Logistic regression indicates blisters with pain and skin rash as the most significant symptoms associated with HSV infection. The present study could be applied for rapid, specific, sensitive and cost-effective diagnosis of HSV-1 and HSV-2 thereby helpful in better patient management through early detection and treatment of HSV.

Laboratory Diagnosis of Neonatal Herpes Simplex Virus Infections

Herpes simplex virus (HSV) is a common and often benign infection in humans; although it less commonly affects newborns, infection in this age group can be devastating. Newborns often present with nonspecific clinical findings, making timely and accurate diagnosis of infection critical. A wide variety of tests are available for detecting herpes simplex virus infection, but only a subset are useful and validated in the newborn population. The current review summarizes available diagnostic testing for neonatal disease, including discussing limitations, unmet needs, and emerging data on molecular testing methods.

Missing Cases of Herpes Simplex Virus (HSV) Infection of the Central Nervous System When the Reller Criteria Are Applied for HSV PCR Testing: a Multicenter Study

Previous studies suggested that herpes simplex virus (HSV) PCR testing can be safely deferred in patients with normal cerebrospinal fluid (CSF) white blood cell (WBC) counts and protein levels as long as they are older than 2 years of age and are not immunocompromised, the so-called Reller criteria. In this multicenter study, we retrospectively assessed the validity of these screening criteria in our setting. A total of 4,404 CSF specimens submitted for HSV PCR testing to the respective microbiology laboratories at the participating hospitals between 2012 and 2018 were included. Six commercially available HSV PCR assays were used across the participating centers. Ninety-one of the 4,404 CSF specimens (2.1%) tested were positive for HSV DNA (75 samples for HSV-1 and 16 for HSV-2). Nine patients failed to meet the Reller criteria, of whom seven were deemed to truly have HSV encephalitis. Overall, no significant correlation between HSV PCR cycle threshold (C_T ) values and WBC counts or total protein levels was found. In addition, median HSV PCR C_T s were comparable between patients who met the Reller criteria and those who did not (P = 0.531). In summary, we show that HSV DNA may be detected in CSF specimens with normal WBC and protein levels collected from immunocompetent individuals older than 2 years with HSV encephalitis. Nevertheless, the data also indicate that the number of cases detected could be lowered at least by half if CSF specimens with borderline WBC counts (4 cells/mm³) as well as children of any age are systematically tested.

Role of the Clinical Microbiology Laboratory in Antimicrobial Stewardship

For adequate antimicrobial stewardship, microbiology needs to move from the laboratory to become physically and verbally amenable to the caregivers of an institution. Herein, we describe the contributions of our microbiology department to the antimicrobial stewardship program of a large teaching hospital as 10 main points ranging from the selection of patients deemed likely to benefit from a fast track approach, to their clinical samples, or the rapid reporting of results via a microbiology hotline, to rapid searches for pathogens and susceptibility testing. These points should serve as guidelines for similar programs designed to decrease the unnecessary use of antimicrobials.

Molecular investigations of viral meningitis among HIV-infected adults in Accra, Ghana

Objective

Meningitis is one of the leading causes of death among patients living with the human immunodeficiency virus (HIV) in sub-Saharan Africa. Based on clinical presentations alone, the different types of meningitis may not be distinguished from each other, consequently accurate laboratory diagnosis is extremely essential. Viruses such as Enteroviruses (EV), Mumps virus (MuV) and Herpes Simplex Virus-1 (HSV-1) are implicated in cases of meningitis. We sought to detect and characterize viral aetiologies of meningitis among HIV-infected adults with the use of molecular tools.

Results

As a subset of a main research work, cerebrospinal fluid specimens were collected from a cross-section of HIV patients at the Fevers Unit of the Korle Bu Teaching Hospital with clinical features suggestive of meningitis but without laboratory confirmation. Laboratory investigations were performed with the use of the real time polymerase chain reaction for pan EV, MuV and HSV-1. None of the viruses investigated in this study was found to be positive for meningitis. However, lymphocytic pleocytosis, normal glucose and elevated protein levels were observed in some of the study participants.

Cost-Effectiveness Study of Criteria for Screening Cerebrospinal Fluid To Determine the Need for Herpes Simplex Virus PCR Testing

The absence of markers of inflammation in the cerebrospinal fluid (CSF) commonly predicts the absence of herpes simplex virus (HSV) central nervous system (CNS) infection. Consequently, multiple authors have proposed and validated criteria for deferring HSV PCR testing of CSF in immunocompetent hosts with normal CSF white blood cell and protein levels (≤5 cells/mm³ and ≤50 mg/dl, respectively). Hosts are considered immunocompetent if they are ≥2 years old and have not had HIV or an organ transplant. Adoption of the criteria may erroneously exclude HSV-infected persons from a necessary diagnostic test or, alternatively, reduce the costs associated with HSV tests with minimal to no effect on patient care. Little is known about the cost-effectiveness of this approach. A decision analysis model was developed to evaluate the adoption of criteria for screening HSV tests of CSF. Estimates of input parameter values combined available literature with a multiyear multisite review at two of the largest health care systems in the United States. Adoption of criteria to screen for HSV test need proved cost-effective when less than 1 in 200 patients deferred from testing truly had an HSV CNS infection. Similar to prior studies, none of the deferred cases had HSV encephalitis (n = 3120). Adoption of these criteria in the United States would save an estimated $127 million ($95 million to $158 million [±25%]) annually. The model calculations remained robust to variation in test cost, prevalence of HSV infection, and random variation to study assumptions. The adoption of criteria to screen HSV PCR tests in CSF represents a cost-effective approach.

Herpes Simplex Encephalitis: an Update

PURPOSE OF REVIEW

The goal of this review is to provide an update on current thinking regarding herpes simplex encephalitis (HSE), emphasizing new information about pathogenesis, diagnosis, and immune responses. Specific questions to be addressed are the following: (1) Is there a genetic predisposition to HSE? (2) What clinical approaches have the greatest impact on improving the long-term outcomes in patients with HSE? And (3) are there immune-mediated mechanisms that may account for relapsing HSE?

RECENT FINDINGS

Toll-like receptor 3 (TLR 3) plays an important role in innate immune responses, including generation of interferons. Multiple single-gene errors in TLR 3 interferon pathways have recently been described in children that result in increased susceptibility to HSE. Conversely, studies in both animal models and humans indicate that both cytolytic viral replication and immune-mediated responses (including cytotoxic T lymphocytes and immune mechanisms mediated by TLR 2) contribute to the pathology of HSV, suggesting possible new therapeutic approaches. In terms of treatment, data clearly indicate that a longer duration between onset of symptoms and initiation of effective antiviral therapy correlates directly with less favorable clinical outcome. Recurrent or relapsing HSE may occasionally occur, but recent observations indicate that many instances of "relapsing HSE", especially in children, are more often anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis triggered by the antecedent HSV infection. Innate immune responses are critical for defense against HSV; genetic defects in this system may predispose patients to HSE. During acute HSE, exuberant immune responses may contribute to the CNS pathology, suggesting that selective immunosuppressive therapy, coupled with potent antiviral drugs, may eventually play a role in the therapeutic management of HSV. While overall clinical outcomes of HSE remain suboptimal, the initiation of high-dose acyclovir therapy as early as possible in the course of the illness provides the best chance for a patient to survive with minimal neurologic damage. Distinguishing relapsing HSE from autoimmune anti-NMDAR antibody encephalitis is critically important because therapeutic approaches will be very different.

Criteria to Screen Molecular Tests for the Diagnosis of Herpes Simplex Virus in the Central Nervous System have no Propensity to Harm

Objectives:

Investigators have ruled out herpes simplex virus (HSV) infection without the detection of herpes simplex deoxyribonucleic acid in cerebrospinal fluid (CSF) (i.e., HSV polymerase chain reaction [PCR]) by laboratory (normal CSF white blood cell count and protein) and clinical criteria (age ≥2 years, no history of human immunodeficiency virus or solid-organ transplant). Compared to HSV PCR of all samples, the algorithm saves money in test costs and may decrease exposure to acyclovir by illustrating the low probability that the patient has HSV. Concern exists that algorithm use may cause harm through alteration of empiric acyclovir treatment in patients with true HSV central nervous system infection.

Methods:

All Department of Veterans Affair's patients with a positive HSV PCR of the CSF between 2000 and 2013 were identified and their medical records reviewed to determine the extent and possible impact of omitted HSV PCR testing by the algorithm.

Results:

Of 6357 total results, 101 patients had a positive CSF HSV PCR in the study period. Among the positive CSF HSV PCR results, the algorithm excluded 7 (7%) from PCR testing. Record review indicated these seven patients not tested by the algorithm with a positive CSF HSV PCR were considered by their attending physician not to have active HSV.

Conclusion:

The algorithm to screen HSV tests had no propensity to harm.

Criteria for reducing unnecessary testing for herpes simplex virus, varicella-zoster virus, cytomegalovirus, and enterovirus in cerebrospinal fluid samples from adults

Excessive utilization of laboratory diagnostic testing leads to increased health care costs. We evaluated criteria to reduce unnecessary nucleic acid amplification testing (NAAT) for viral pathogens in cerebrospinal fluid (CSF) samples from adults. This is a single-center split retrospective observational study with a screening cohort from 2008 to 2012 and a validation cohort from 2013. Adults with available results for herpes simplex virus 1/2 (HSV-1/2), varicella-zoster virus (VZV), cytomegalovirus (CMV), or enterovirus (EV) NAAT with CSF samples between 2008 and 2013 were included (n = 10,917). During this study, 1.3% (n = 140) of viral NAAT studies yielded positive results. The acceptance criteria of >10 nucleated cells/μl in the CSF of immunocompetent subjects would have reduced HSV-1/2, VZV, CMV, and EV testing by 63%, 50%, 44%, and 51%, respectively, from 2008 to 2012. When these criteria were applied to the 2013 validation data set, 54% of HSV-1/2, 57% of VZV, 35% of CMV, and 56% of EV tests would have been cancelled. No clinically significant positive tests would have been cancelled in 2013 with this approach. The introduction of a computerized order entry set was associated with increased test requests, suggesting that computerized order sets may contribute to unnecessary testing. Acceptance criteria of >10 nucleated cells/μl in the CSF of immunocompetent adults for viral CSF NAAT assays would increase clinical specificity and preserve sensitivity, resulting in significant cost savings. Implementation of these acceptance criteria led to a 46% reduction in testing during a limited follow-up period.

A commentary on the role of molecular technology and automation in clinical diagnostics

Historically, the identification of bacterial or yeast isolates has been based on phenotypic characteristics such as growth on defined media, colony morphology, Gram stain, and various biochemical reactions, with significant delay in diagnosis. Clinical microbiology as a medical specialty has embraced advances in molecular technology for rapid species identification with broad-range 16S rDNA polymerase chain reaction (PCR) and matrix-assisted laser desorption and/or ionization time of flight (MALDI-TOF) mass spectrometry demonstrated as accurate, rapid, and cost-effective methods for the identification of most, but not all, bacteria and yeasts. Protracted conventional incubation times previously necessary to identify certain species have been mitigated, affording patients quicker diagnosis with associated reduction in exposure to empiric broad-spectrum antimicrobial therapy and shortened hospital stay. This short commentary details such molecular advances and their implications in the clinical microbiology setting.