Differences in laboratory findings for cerebrospinal fluid specimens obtained from patients with meningitis or encephalitis due to herpes simplex virus (HSV) documented by detection of HSV DNA

Update on Viral Infections Involving the Central Nervous System in Pediatric Patients

Infections of the central nervous system (CNS) are mainly caused by viruses, and these infections can be life-threatening in pediatric patients. Although the prognosis of CNS infections is often favorable, mortality and long-term sequelae can occur. The aims of this narrative review were to describe the specific microbiological and clinical features of the most frequent pathogens and to provide an update on the diagnostic approaches and treatment strategies for viral CNS infections in children. A literature analysis showed that the most common pathogens worldwide are enteroviruses, arboviruses, parechoviruses, and herpesviruses, with variable prevalence rates in different countries. Lumbar puncture (LP) should be performed as soon as possible when CNS infection is suspected, and cerebrospinal fluid (CSF) samples should always be sent for polymerase chain reaction (PCR) analysis. Due to the lack of specific therapies, the management of viral CNS infections is mainly based on supportive care, and empiric treatment against herpes simplex virus (HSV) infection should be started as soon as possible. Some researchers have questioned the role of acyclovir as an empiric antiviral in older children due to the low incidence of HSV infection in this population and observed that HSV encephalitis may be clinically recognizable beyond neonatal age. However, the real benefit-risk ratio of selective approaches is unclear, and further studies are needed to define appropriate indications for empiric acyclovir. Research is needed to find specific therapies for emerging pathogens. Moreover, the appropriate timing of monitoring neurological development, performing neuroimaging evaluations and investigating the effectiveness of rehabilitation during follow-up should be evaluated with long-term studies.

[Post-dural puncture headache]

Post-dural puncture headache belongs to the group of secondary headache disorders and is a typical complication of intended or unintended dural puncture. The main symptom is orthostatic headache, which can be accompanied by neurological symptoms such as diplopia depending on the extent of the cerebrospinal fluid leak. The course of this headache is predominantly benign, showing spontaneous improvement over a couple of days, although severe cases are described in the literature. The following article provides an overview of the current knowledge about the headache's pathophysiology, diagnostic work-up and therapy.

[Post-dural puncture headache]

Post-dural puncture headache belongs to the group of secondary headache disorders and is a typical complication of intended or unintended dural puncture. The main symptom is orthostatic headache, which can be accompanied by neurological symptoms such as diplopia depending on the extent of the cerebrospinal fluid leak. The course of this headache is predominantly benign, showing spontaneous improvement over a couple of days, although severe cases are described in the literature. The following article provides an overview of the current knowledge about the headache's pathophysiology, diagnostic work-up and therapy.

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.

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.

Mechanisms of Blood-Brain Barrier Disruption in Herpes Simplex Encephalitis

Herpes simplex encephalitis (HSE) is often caused by infection with herpes simplex virus 1 (HSV-1), a neurotropic double-stranded DNA virus. HSE infection always impacts the temporal and frontal lobes or limbic system, leading to edema, hemorrhage, and necrotic changes in the brain parenchyma. Additionally, patients often exhibit severe complications following antiviral treatment, including dementia and epilepsy. HSE is further associated with disruptions to the blood-brain barrier (BBB), which consists of microvascular endothelial cells, tight junctions, astrocytes, pericytes, and basement membranes. Following an HSV-1 infection, changes in BBB integrity and permeability can result in increased movement of viruses, immune cells, and/or cytokines into the brain parenchyma. This leads to an enhanced inflammatory response in the central nervous system and further damage to the brain. Thus, it is important to protect the BBB from pathogens to reduce brain damage from HSE. Here, we discuss HSE and the normal structure and function of the BBB. We also discuss growing evidence indicating an association between BBB breakdown and the pathogenesis of HSE, as well as future research directions and potential new therapeutic targets. Graphical Abstract During herpes simplex encephalitis, the functions and structures of each composition of BBB have been altered by different factors, thus the permeability and integrity of BBB have been broken. The review aim to explore the potential mechanisms and factors in the process, probe the next research targets and new therapeutic targets.

[Clinical, epidemiological, and etiological studies of adult aseptic meningitis: a report of 12 cases of herpes simplex meningitis, and a comparison with cases of herpes simplex encephalitis]

We treated 437 cases of adult aseptic meningitis and 12 cases (including 2 recurrent patients; age, 31.8 ± 8.9 years; 7 females) of herpes simplex meningitis from 2004 to 2016. The incidence rate of adult herpes simplex meningitis in the cases with aseptic meningitis was 2.7%. One patient was admitted during treatment of genital herpes, but no association was observed between genital herpes and herpes simplex meningitis in the other cases. The diagnoses were confirmed in all cases as the cerebrospinal fluid (CSF) was positive for herpes simplex virus (HSV)-DNA. For diagnosis confirmation, the DNA test was useful after 2-7 days following initial disease onset. Among other types of aseptic meningitis, the patients with herpes simplex meningitis showed relatively high white blood cell counts and relatively high CSF protein and high CSF cell counts. CSF cells showed mononuclear cell dominance from the initial stage of the disease. During same period, we also experienced 12 cases of herpes simplex encephalitis and 21 cases of non-hepatic acute limbic encephalitis. Notably, the patients with herpes simplex meningitis were younger and their CSF protein and cells counts were higher than those of the patients with herpes simplex encephalitis.

CXCL11 production in cerebrospinal fluid distinguishes herpes simplex meningitis from herpes simplex encephalitis

Background

The closely related herpes simplex viruses 1 and 2 can cause inflammations of the central nervous system (CNS), where type 1 most often manifest as encephalitis (HSE), and type 2 as meningitis (HSM). HSE is associated with severe neurological complications, while HSM is benign in adults. We proposed that studying the chemokine and cytokine production in cerebrospinal fluid (CSF) and serum could indicate why two closely related viruses exhibit different severity of their accompanied CNS inflammation.

Methods

Secretion patterns of 30 chemokines and 10 cytokines in CSF of adult patients with acute HSE (n = 14) and HSM (n = 20) in the initial stage of disease were analyzed and compared to control subjects without viral central nervous system infections and to levels in serum.

Results

Most measured chemokines and cytokines increased in CSF of HSE and HSM patients. Overall, the CSF chemokine levels were higher in CSF of HSM patients compared to HSE patients. However, only five chemokines reached levels in the CSF that exceeded those in serum facilitating a positive CSF-serum chemokine gradient. Of these, CXCL8, CXCL9, and CXCL10 were present at high levels both in HSE and HSM whereas CXCL11 and CCL8 were present in HSM alone. Several chemokines were also elevated in serum of HSE patients but only one in HSM patients. No chemokine in- or efflux between CSF and serum was indicated as the levels of chemokines in CSF and serum did not correlate.

Conclusions

We show that HSM is associated with a stronger and more diverse inflammatory response in the CNS compared to HSE in the initial stage of disease. The chemokine patterns were distinguished by the exclusive local CNS production of CXCL11 and CCL8 in HSM. Inflammation in HSM appears to be restricted to the CNS whereas HSE also was associated with systemic inflammation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-017-0907-5) contains supplementary material, which is available to authorized users.

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.

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.

Clinical and Laboratory Findings That Differentiate Herpes Simplex Virus Central Nervous System Disease from Enteroviral Meningitis

Background. It can be difficult for clinicians to distinguish between the relatively benign enteroviral (EnV) meningitis and potentially lethal herpes simplex virus (HSV) central nervous system (CNS) disease. Very limited evidence currently exists to guide them. Objective. This study sought to identify clinical features and cerebrospinal fluid (CSF) findings associated with HSV CNS disease. Methods. Given that PCR testing often is not immediately available, this chart review study sought to identify clinical and cerebrospinal fluid (CSF) findings associated with HSV meningitis over a 6-year period. In cases where PCR was not performed, HSV and EnV were assigned based on clinical criteria. Results. We enrolled 166 consecutive patients: 40 HSV and 126 EnV patients. HSV patients had a mean 40.4 versus 31.3 years for EnV, p = 0.005, seizures 21.1% versus 1.6% for EnV, p < 0.001, altered mental status 46.2% versus 3.2% for EnV, p < 0.001, or neurological deficits 44.7% versus 3.9% for EnV, p < 0.001. CSF neutrophils were lower in HSV (median 3.0% versus 9.5%, p = 0.0002); median lymphocytes (87.0% versus 67.0%, p = 0.0004) and protein (0.9 g/L versus 0.6 g/L, p = 0.0005) were elevated. Conclusion. Our study found that HSV patients were older and more likely to have seizure, altered mental status, or neurological deficits than patients with benign EnV meningitis. HSV cases had lower CSF neutrophils, higher lymphocytes, and higher protein levels.

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.

Comparison of clinical manifestations, outcomes and cerebrospinal fluid findings between herpes simplex type 1 and type 2 central nervous system infections in adults

In previous reports on the viral causes of central nervous system (CNS) infections, it has been generally recognized that HSV-1 is a major cause of encephalitis, while HSV-2 is the predominant cause of aseptic meningitis in adults. To examine this matter, the clinical characteristics in the two types of HSV CNS infections were investigated. In a retrospective cohort study which included all adult patients (≥16 years) between January 1999 and December 2013 in a 2,700-bed tertiary care hospital, all the patients in whom PCR of the CSF for HSV was positive were identified. Ninety-five patients with positive CSF PCR results for HSV were included, 21 with HSV-1 and 74 with HSV-2. Many patients with HSV-1 had encephalitis (13/21, 61.9%), whereas most patients with HSV-2 had meningitis (62/74, 83.8%). However, HSV-1 and HSV-2 accounted for similar proportion of patients with HSV encephalitis (13/25, 52.0% vs. 12/25, 48.0%). Neurological sequelae were more frequent among patients with HSV-1 (9/21, 42.9% vs. 6/74, 8.1%; P = 0.001). The present study suggests that HSV-2 is not only a major cause of aseptic meningitis, but also it may cause serious manifestation as HSV-1 encephalitis in adults.

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

The determination of herpes simplex virus (HSV) infection using a PCR assay is one of the most commonly requested tests for analysis of cerebrospinal fluid (CSF), although only a very low proportion of results are positive. A previously reported study showed that selecting only those CSF samples with >5 leukocytes/mm(3) or a protein level of >50 mg/dl was adequate for the diagnostic workup. The aim of the present study was to assess the reliability of alternative acceptance criteria based on elevated CSF white blood cell counts (>10 cells/mm(3)). We analyzed all requests for HSV PCR received between January 2008 and December 2011. CSF samples were accepted for analysis if they had >10 cells/mm(3) or if the sample was from an immunocompromised patient or a child aged <2 years. In order to evaluate our selection criteria, we identified those CSF samples with a leukocyte count of 5 to 10 cells/mm(3) or protein levels of >50 mg/dl in order to test them for HSV type 1 and 2 (HSV-1 and HSV-2) DNA. During the study period, 466 CSF samples were submitted to the microbiology laboratory for HSV PCR. Of these, 268 (57.5%) were rejected, and 198 (42.5%) were tested according to our routine criteria. Of the tested samples, 11 (5.5%) were positive for HSV DNA (7 for HSV-1 and 4 for HSV-2). Of the 268 rejected specimens, 74 met the criteria of >5 cells/mm(3) and/or protein levels of >50 mg/dl. Of these, 70 (94.6%) were available for analysis. None of the samples yielded a positive HSV PCR result. Acceptance criteria based on CSF leukocyte counts, host immune status, and age can help to streamline the application of HSV PCR without reducing sensitivity.

Neonatal infectious diseases: evaluation of neonatal sepsis

Neonatal sepsis remains a feared cause of morbidity and mortality in the neonatal period. Maternal, neonatal, and environmental factors are associated with risk of infection, and a combination of prevention strategies, judicious neonatal evaluation, and early initiation of therapy are required to prevent adverse outcomes. This article reviews recent trends in epidemiology and provides an update on risk factors, diagnostic methods, and management of neonatal sepsis.

Central nervous system herpes simplex virus infection in afebrile children with seizures

Central nervous system herpes simplex virus infection is suspected in patients presenting with acute-onset seizures and lethargy. The potential neurologic sequelae from untreated herpes infection can prompt empirical acyclovir therapy, even in afebrile subjects. The objectives of this study were to determine the frequency of central nervous system herpes simplex virus infection in children presenting with afebrile seizures and to assess the need for empirical acyclovir therapy. Clinical and laboratory data of children with acute-onset afebrile seizures and children with central nervous system herpes simplex virus infection were compared. Polymerase chain reaction and viral cultures of the cerebrospinal fluid for herpes simplex virus infection were negative in all subjects with afebrile seizures; 32.7% of these subjects were empirically treated with acyclovir. In conclusion, central nervous system herpes simplex virus infection is uncommon in children presenting with afebrile seizures, and acyclovir therapy is rarely necessary in subjects with normal neurologic examination and cerebrospinal fluid analysis.

Neuro-intensive care of patients with acute CNS infections

Infections in the central nervous system (CNS) are caused by a wide range of microorganisms resulting in distinct clinical syndromes including meningitis, encephalitis, and pyogenic infections, such as empyema and brain abscess. Bacterial and viral infections in the CNS can be rapidly fatal and can result in severe disability in survivors. Appropriate identification and acute management of these infections often occurs in a critical care setting and is vital to improving outcomes in this group of patients. This review of diagnosis and management of acute bacterial and viral infections in the CNS provides a general approach to patients with a suspected CNS infection and also provides a more detailed review of the diagnosis and management of patients with suspected bacterial meningitis, viral encephalitis, brain abscess, and subdural empyema.

Relative quantity of cerebrospinal fluid herpes simplex virus DNA in adult cases of encephalitis and meningitis

Herpes simplex virus (HSV) remains an important cause of meningitis and encephalitis in adults, and polymerase chain reaction (PCR)-based tests are the "gold standard" for diagnosis. The objective of this study was to assess differences in semiquantitative PCR values, based on the crossing threshold (Ct) value for cases of HSV meningitis and encephalitis. A retrospective chart review was performed for 29 patients with a documented diagnosis of HSV meningitis or encephalitis during the course of 5 years from a large urban academic hospital. Demographic information, cerebrospinal fluid (CSF) laboratory findings, and PCR data were obtained for each patient. There was no statistically significant difference in the Ct values in patients with meningitis or encephalitis. In addition, no differences were found in CSF chemistry and hematology parameters. There is a broad range in relative concentrations of HSV DNA in the CSF in cases of meningitis and encephalitis.

Herpes simplex I encephalitis presenting as a brain haemorrhage with normal cerebrospinal fluid analysis: a case report

Introduction

Herpes simplex encephalitis is a potentially lethal infection that should be recognised as soon as possible. The combination of clinical history and examination, brain computed tomography or magnetic resonance imaging and lumbar puncture has been used to establish a diagnosis.

Case presentation

We present a patient who had a suggestive history but a totally normal lumbar puncture and only evidence of intracerebral haemorrhage in the brain magnetic resonance imaging. Diagnosis was made by using the cerebrospinal fluid polymerase chain reaction for herpes simplex virus.

Conclusion

Herpes simplex encephalitis is being increasingly diagnosed with the availability of new diagnostic techniques. Herpes simplex encephalitis can present with the combination of haemorrhage and normal cerebrospinal fluid. Awareness of this common but, if left untreated, devastating condition should increase.

[Herpes simplex virus meningitis in 11 patients]

METHOD

We reviewed retrospectively the demographic, clinical, biological characteristics and outcomes of 11 patients with HSV meningitis.

RESULTS

Among the 11 patients, six were infected with HIV, four had a documented history of genital herpes, and one recurrent meningitis. In all cases, the onset of symptoms was abrupt, with severe headache and fever. On admission, 9/11 patients had severe meningismus; two patients had HSV anogenital ulcerations. CSF analysis showed in every case a significant increased of leukocytes with a lymphocytic pleocytosis, a mild elevated protein level and a normal glucose level. HSV was detected in the CSF in every case by PCR: the typing performed on six patients was positive in every case for HSV-2. Intravenous acyclovir (IV ACV) was started in 10/11 cases (range: 3-10 days), switched to valaciclovir (VACV) (range: 5-7 days); one patient was treated with ACV per os for 10 days. The total resolution of symptoms occurred within 48hours in every case. Two patients presented with recurrent HSV-2 meningitis in the next two months, with favorable outcome under IV ACV: a switch to long term VACV 500mg/day was prescribed without any recurrence. No patient presented with recurrence after a median follow-up of 30 months.

CONCLUSION

Early recognition and treatment might improve the outcome of such infections. Adjunctive oral VACV after IV ACV treatment seems to be associated with a good clinical response in patients presenting with HSV meningitis. The duration of such treatments, including prophylactic treatments to prevent recurrent episodes must be better documented.

Validation of laboratory screening criteria for herpes simplex virus testing of cerebrospinal fluid

Most patients with herpes simplex virus (HSV) central nervous system (CNS) infection have abnormal cerebrospinal fluid (CSF) indices. Therefore, we implemented screening criteria based on CSF values and host immune status to guide testing. All CSF samples submitted for HSV PCR analysis from January 1999 through December 2004 were included in the study. Specimens from patients with human immunodeficiency virus, a history of transplants, an age of <2 years, a CSF white blood cell count of >5 cells/mm(3), or a protein level of >50 mg/dl were tested upon request. All other samples were rejected and frozen. To validate our screening criteria, rejected specimens were pooled and tested retrospectively. Electronic medical records were also reviewed. A total of 1,659 HSV PCR requests from 1,458 patients were screened. Of the 1,296 specimens (78.1%) accepted for testing, 1,213 were negative, 7 were positive for HSV type 1 (HSV-1), 26 were positive for HSV-2, and 50 had unavailable results. Sixteen requests were rejected because an alternative microbiologic diagnosis had been established. Of the 347 samples rejected based on criteria, 222 (64.0%) remained available for pooled testing. No HSV-1-positive samples were identified in the rejected specimens. Two rejected specimens tested positive for HSV-2 DNA, but both met acceptance criteria which had not been communicated to the laboratory. Few patients (7.8%) with rejected specimens were treated with acyclovir, which suggests a low clinical concern for HSV encephalitis. Acceptance criteria based on CSF parameters and host immune status saved time and cost and did not miss patients with HSV CNS infection. Communication between the clinician and the laboratory is imperative for a successful screening program.

Appropriate use of polymerase chain reaction for detection of herpes simplex virus 2 in cerebrospinal fluid of patients at an inner-city hospital

Polymerase chain reaction (PCR) tests that detect herpes simplex virus (HSV) DNA in cerebrospinal fluid (CSF) are increasingly used to diagnose central nervous system (CNS) infections caused by HSV. To determine proper utilization of this test at an inner-city hospital, we performed a case-control study of adult patients, with HSV detected in CSF by PCR. Retrospective review of characteristics of adult patients hospitalized between 1997 and 2000 with CSF positive for HSV was done and compared to control patients with suspected CNS infection and negative CSF PCR. CSF from 1174 patients was tested; 20 (1.7%) had HSV DNA detected, 19/20 were HSV-2 and 1 was HSV-1. The HSV-2 cases were females (74%), with a median age of 41 years, of African-American ethnicity (100%). Of the cases, 90% had acute aseptic meningitis versus 13% controls (P < .001). Recurrent meningitis occurred in 42% cases and 3% controls (P < .001). CSF parameters significantly associated with HSV-2 positivity was lymphocytic pleocytosis (median leukocyte, 475 cell/mm3, 90% lymphocytes) (P < .001). In conclusion, HSV-1 was rarely detected in CSF of patients with suspected CNS infection. HSV-2 is more frequent, predominantly in young African-American women with lymphocytic aseptic meningitis, and is often recurrent. PCR testing for HSV-2 in CSF at inner-city hospitals can be greatly reduced by the application of these parameters.

Factors influencing PCR detection of viruses in cerebrospinal fluid of patients with suspected CNS infections

BACKGROUND

Polymerase chain reaction (PCR) is used to detect viruses in the cerebrospinal fluid (CSF) of patients with neurological disease. However, data to assist its use or interpretation are limited.

OBJECTIVE

We investigated factors possibly influencing viral detection in CSF by PCR, which will also help clinicians interpret positive and negative results.

METHODS

CSF from patients with was tested for human herpesviruses types 1-6, JC virus, enteroviruses, and Toxoplasma gondii. The likelihood of central nervous system (CNS) infection was classified as likely, possible, or unlikely. PCR findings in these categories were compared using single variable and logistic regression analysis.

RESULTS

Of 787 samples tested, 97 (12%) were PCR positive for one or more viruses. Of episodes likely to be CNS viral infections, 30% were PCR positive compared to 5% categorised as unlikely. The most frequent positive findings were Epstein Barr virus (EBV), enteroviruses, and herpes simplex virus (HSV). Enteroviruses and HSV were found predominantly in the likely CNS viral infection group, whereas EBV was found mainly in the unlikely group. Positive PCR results were more likely when there were 3-14 days between symptom onset and lumbar puncture, and when CSF white cell count was abnormal, although a normal CSF did not exclude a viral infection.

CONCLUSIONS

The diagnostic yield of PCR can be maximised by using sensitive assays to detect a range of pathogens in appropriately timed CSF samples. PCR results, in particular EBV, should be interpreted cautiously when symptoms cannot readily be attributed to the virus detected.

[Value of the polymerase chain reaction in the diagnosis of herpes infections of the nervous system]

OBJECTIVE

To assess the performance of a polymerase chain reaction (PCR) method in cerebrospinal fluid (CSF) for the diagnosis of nervous system infections caused by herpesvirus, and to estimate the incidence of encephalitis due to herpes simplex virus type 1 in the adult population of the island of Gran Canaria.

METHODS

We studied 330 CSF specimens from 312 patients (281 HIV-negative and 31 HIV-positive) remitted to investigate clinically suspected encephalitis or meningitis, or to study neuropathy or demyelinating disease. A multiplex PCR technique was used to detect herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), varicella-zoster virus (VZV), human cytomegalovirus (CMV), Epstein-Barr virus and human herpesvirus type 6. The patients' clinical records were reviewed to establish the definite diagnosis.

RESULTS

Nine samples from eight patients (2.6%) showed positive results (9.7% of patients with pathological CSF and none with normal CSF). The eight patients had clinical and analytic findings of herpesvirus nervous system infection: HSV-1 DNA in four patients with encephalitis, HSV-2 DNA in one patient with meningitis, VZV DNA in two patients with meningitis and CMV DNA in one HIV-positive patient with encephalitis. Herpesvirus was the cause of 50% of encephalitis cases and 10% of meningitis cases. The incidence of HSV-1 encephalitis was five cases per million inhabitants per year.

CONCLUSIONS

Diagnosis of herpesvirus nervous system infections by PCR in CSF is not appropriate when CSF parameters are normal. We found a higher incidence of herpesvirus encephalitis than has been reported in other studies.

Clinical spectrum and laboratory characteristics associated with detection of herpes simplex virus DNA in cerebrospinal fluid

OBJECTIVE

To determine the clinical, neurologic, and laboratory characteristics of patients with herpes simplex virus (HSV) type 1 (HSV-1) or HSV type 2 (HSV-2) DNA detected in cerebrospinal fluid (CSF) with use of polymerase chain reaction.

PATIENTS AND METHODS

Clinical, laboratory, and demographic data were determined from 249 CSF specimens (collected from 247 patients >10 years of age) that tested positive for HSV-1 or HSV-2 DNA at the Mayo Clinic from January 1999 to August 2000.

RESULTS

The median age of the 200 patients whose age was available was 70 years vs 40 years for those with HSV-1 or HSV-2 DNA in CSF, respectively. Detailed data were available for 39 and 78 patients with positive polymerase chain reaction results for HSV-1 and HSV-2, respectively. Of those with HSV-1 DNA detected in CSF, 89% had encephalitis, whereas most patients with HSV-2 DNA detected in CSF had findings compatible with meningitis. Only 5 (7%) of 69 patients in whom HSV-2 was detected in CSF had genital lesions at presentation, and none of the assessable patients with HSV-2 who had recurrent meningitis had active genital lesions at presentation.

CONCLUSION

The vast majority (82%) of patients with HSV-2 detected in CSF had no history of genital herpes and no lesions at the time of presentation. Polymerase chain reaction assays designed to detect HSV in CSF should detect HSV-1 and HSV-2 and differentiate between HSV-1 and HSV-2.

Introducing a molecular test into the clinical microbiology laboratory: development, evaluation, and validation

CONTEXT

In the mid-1980s, the polymerase chain reaction methodology for the amplification of minute amounts of target DNA was successfully developed and then introduced into clinical use; such technology has led to a revolution in diagnostic testing. Despite enormous advances in the detection of infectious agents by amplification methods, there are also limitations that must be addressed.

OBJECTIVE

To highlight the pertinent steps and issues associated with the introduction of an amplification assay into a clinical microbiology laboratory as well as the subsequent ongoing activities following its introduction into routine laboratory use.

DATA SOURCES

Data were obtained from literature searches from 1990 through September 2002 using the subject headings "polymerase chain reaction," "molecular assays," and "amplification" as well as publications of the National Committee for Clinical Laboratory Standards.

DATA EXTRACTION AND SYNTHESIS

Using the findings obtained from these studies and publications, the process of introducing a molecular assay into the clinical microbiology laboratory was broken down into 4 major components: (1) initial phase of assay development, (2) polymerase chain reaction assay verification in which analytic sensitivity and specificity is determined, (3) assay validation to determine clinical sensitivity and specificity, and (4) interpretation of results and ongoing, required activities. The approach, as well as the advantages and limitations involved in each step of the process, was highlighted and discussed within the context of the published literature.

CONCLUSIONS

The application of molecular testing methods in the clinical laboratory has dramatically improved our ability to diagnose infectious diseases. However, the clinical usefulness of molecular testing will only be maximized to its fullest benefit by appropriate and careful studies correlating clinical findings with assay results.