Role of the virology laboratory in diagnosis and management of patients with central nervous system disease

Viral meningitis and encephalitis: an update

PURPOSE OF REVIEW

The most common infectious etiologies of meningitis and encephalitis are viruses. In this review, we will discuss current epidemiology, prevention, diagnosis, and treatment of the most common causes of viral meningitis and encephalitis worldwide.

RECENT FINDINGS

Viral meningitis and encephalitis are increasingly diagnosed as molecular diagnostic techniques and serologies have become more readily available worldwide but recent progress in novel antiviral therapies remains limited. Emerging and re-emerging viruses that have caused endemic or worldwide outbreaks or epidemics are arboviruses (e.g., West Nile virus, Japanese encephalitis, Tick borne encephalitis, Dengue, Zika, Toscana), enteroviruses (e.g., Enterovirus 71, Enterovirus D68), Parechoviruses, respiratory viruses [e.g., severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza, metapneumoviruses, measles, mumps], and herpes viruses [e.g., herpes simplex virus (HSV) type 1 (HSV-1), HSV-2, human herpes (HV) 6, varicella zoster virus (VZV)]. Future efforts should concentrate in increasing availability for those viruses with effective vaccination [e.g., Japanese encephalitis, Tick borne encephalitis, varicella zoster viruses, SARS-CoV-2, influenza], prompt initiation of those with encephalitis with treatable viruses (e.g., HSV-1, VZV), increasing the diagnostic yield by using novel techniques such as metagenomic sequencing and avoiding unnecessary antibiotics in those with viral meningitis or encephalitis.

SUMMARY

We review the current epidemiology, clinical presentation, diagnosis, and treatment of the common causative agents of viral meningitis and encephalitis worldwide.

Viral meningitis in Sudanese children: Differentiation, etiology and review of literature

Diagnosis of viral meningitis (VM) is uncommon practice in Sudan and there is no local viral etiological map. We therefore intended to differentiate VM using standardized clinical codes and determine the involvement of herpes simplex virus types-1 and 2 (HSV-1/2), varicella zoster virus, non-polio human enteroviruses (HEVs), and human parechoviruses in meningeal infections in children in Sudan. This is a cross-sectional hospital-based study. Viral meningitis was differentiated in 503 suspected febrile attendee of Omdurman Hospital for Children following the criteria listed in the Clinical Case Definition for Aseptic/Viral Meningitis. Patients were children age 0 to 15 years. Viral nucleic acids (DNA/RNA) were extracted from cerebrospinal fluid (CSF) specimens using QIAamp® UltraSens Virus Technology. Complementary DNA was prepared from viral RNA using GoScriptTM Reverse Transcription System. Viral nucleic acids were amplified and detected using quantitative TaqMan® Real-Time and conventional polymerase chain reactions (PCRs). Hospital diagnosis of VM was assigned to 0%, when clinical codes were applied; we considered 3.2% as having VM among the total study population and as 40% among those with proven infectious meningitis. Two (0.4%) out of total 503 CSF specimens were positive for HSV-1; Ct values were 37.05 and 39.10 and virus copies were 652/PCR run (261 × 103/mL CSF) and 123/PCR run (49.3 × 103/mL CSF), respectively. Other 2 (0.4%) CSF specimens were positive for non-polio HEVs; Ct values were 37.70 and 38.30, and the approximate virus copies were 5E2/PCR run (~2E5/mL CSF) and 2E2/PCR run (~8E4/mL CSF), respectively. No genetic materials were detected for HSV-2, varicella zoster virus, and human parechoviruses. The diagnosis of VM was never assigned by the hospital despite fulfilling the clinical case definition. Virus detection rate was 10% among cases with proven infectious meningitis. Detected viruses were HSV-1 and non-polio HEVs. Positive virus PCRs in CSFs with normal cellular counts were seen.

Syndrome Evaluation System for Simultaneous Detection Pathogens Causing Acute Encephalitic Syndrome in India, Part-1: Development and Standardization of the Assay

A large number of organisms are known to cause acute encephalitic syndrome (AES). A number of diagnostic tests have to be performed in order to arrive at a probable pathogen causing AES thus making it a very time consuming, laborious and expensive. The problem is further compounded by the lack of availability of sufficient volume of Cerebrospinal fluid (CSF). Thus, there is an urgent need of a diagnostic tool for the simultaneous detection of all probable pathogens responsible for causing AES. Here we report the development of a novel diagnostic method, Syndrome Evaluation System (SES) for the simultaneous detection of 22 pathogens including RNA and DNA Viruses, bacteria, fungi, and parasite all endemic to India and Southeast Asia in a single sample using a novel multiplexing strategy. Syndrome Evaluation System (SES) involves isolation of nucleic acid, multiplex amplification of the DNA, and cDNA followed by identification of the amplified product by sequence specific hybridization on SES platform with the final read out being a visually recordable colored signal. The total time required to carry out this diagnostic procedure is 7 h. The SES was standardized using the commercially available vaccines, panels and cell culture grown quantified viruses/bacteria/fungi. The limit of detection (LOD) of SES ranged between 0.1 and 50 viral particles per ml of CSF and 100 to 200 bacterial cells or 5 parasites per ml of CSF, along with 100% specificity. Precision studies carried out as per the Clinical Laboratory Improvement Amendments (CLIA) guidelines, using two concentrations of each pathogen one the LOD and the other double the LOD, clearly demonstrated, that inter/intra assay variability was within the limits prescribed by the guidelines. SES is a rapid molecular diagnostic tool for simultaneous identification of 22 etiological agents of AES encountered both in sporadic and outbreak settings.

CSF in acute and chronic infectious diseases

Infections of the nervous system are an important and challenging aspect of clinical neurology. Immediate correct diagnosis enables to introduce effective therapy, in conditions that without diagnosis may leave the patient with severe neurological incapacitation and sometimes even death. The cerebrospinal fluid (CSF) is a mirror that reflects nervous system pathology and can promote early diagnosis and therapy. The present chapter focuses on the CSF findings in neuro-infections, mainly viral and bacterial. Opening pressure, protein and glucose levels, presence of cells and type of the cellular reaction should be monitored. Other tests can also shed light on the causative agent: serology, culture, staining, molecular techniques such as polymerase chain reaction. Specific examination such as panbacterial and panfungal examinations should be examined when relevant. Our chapter is a guide-text that combines clinical presentation and course with CSF findings as a usuaful tool in diagnosis of neuroinfections.

Enterovirus meningitis in Greece from 2003-2005: diagnosis, CSF laboratory findings, and clinical manifestations

Enteroviruses (EVs) are the most commonly identified cause of aseptic meningitis. Rapid detection and characterization of EV meningitis is essential in making decisions for patient management and treatment. A total of 52 cases of acute aseptic meningitis that occurred from March 2003 to April 2005 were investigated for EVs using viral culture and/or molecular methods directly in the cerebrospinal fluid (CSF). EVs were detected in 21 out of 52 (40.4%) patients using reverse transcription-PCR (RT-PCR) and/or tissue culture. EVs were isolated from six out of 37 (16.2%) cultured specimens, while 20 out of 52 (38.4%) specimens yielded positive results when 5'non-coding region (5'NCR) RT-PCR assay was used. One specimen that was culture-positive was RT-PCR-negative. Using the VP1-2A RT-PCR and sequence analysis, 14 of the 21 positive EVs were identified as: four strains of Coxsackie virus B5, five echovirus 11, two echovirus 9, one echovirus 5, one echovirus 14, and one Coxsackie virus A9. Fever, headache, vomiting, and stiff neck were the most pronounced symptoms. Pleocytosis with the predominance of lymphocytes and mild elevated protein levels characterized the CSF specimens. Coxsackie virus B5 and echovirus 11 were the predominant serotypes during the study period. Although there was seasonal enteroviral activity (April-November), cases also occurred in the cold months. The 5'NCR and VP1-2A RT-PCR with sequence analysis were found to be superior to conventional methods for direct diagnosis and the typing of EVs.

Evaluation of a commercially available reverse transcription-PCR enzyme immunoassay (Enterovirus Consensus kit) for the diagnosis of enterovirus central nervous system infections

A commercial reverse transcription (RT)-PCR amplification method was compared with culture for the diagnosis of enterovirus meningitis. In total, 99 cerebrospinal fluid (CSF) specimens were examined with the Enterovirus Consensus kit and shell vial culture. RT-PCR allowed the amplification of enterovirus cDNA and its detection in a microtitre plate by hybridisation. Clinical information and CSF analysis were used to resolve the discrepancy in results. The detection limit of the RT-PCR assay was determined with the Third European Union Concerted Action Enterovirus Proficiency Panel. There were 34 true-positive CSF specimens. Of these, RT-PCR detected 33 (sensitivity 97%), while culture detected 19 (sensitivity 54.5%). RT-PCR failed to detect one culture-positive specimen that contained inhibitors. When samples from the Third European Union Concerted Action Enterovirus Proficiency Panel were tested, the RT-PCR method gave identical results to those expected. The Enterovirus Consensus kit was rapid and statistically more sensitive than culture (p < 0.01) for the detection of enteroviruses in CSF, and may offer considerable benefits in the clinical management of patients with enterovirus meningitis.

Molecular identification of enteroviruses responsible for an outbreak of aseptic meningitis; implications in clinical practice and epidemiology

An outbreak of aseptic meningitis was recorded in Greece during the year 2001. Detection of the clinical strains was achieved by performing reverse transcription-polymerase chain reaction (RT-PCR) on RNA isolated from cell cultures inoculated with treated faecal material from the patients. Serotypic identification of the isolates with mixed equine antisera pools followed and the RT-PCR amplicons were further studied by restriction fragment length polymorphism analysis and sequencing. Fifty-three clinical enterovirus strains were isolated from respective cases of suspected enterovirus infection, most of which showed the clinical symptoms of aseptic meningitis. Echovirus (ECV) 6 was the most frequently isolated serotype, followed by coxsackie B viruses, ECV13, poliovirus type 1 (PV1) vaccine strain and ECV30. Nucleotide sequence analysis showed the existence of different genetic groups on the basis of the 5'-untranslated region (5'-UTR) of the genome, which circulated in the population during the same time period. Different serotypes belonged to the same genetic group and vice versa. The 5'-UTR seems to be appropriate for the investigation of enterovirus evolution and epidemiology.

Highly sensitive assay for detection of enterovirus in clinical specimens by reverse transcription-PCR with an armored RNA internal control

The objective of the present study was the development of a diagnostic reverse transcription (RT)-PCR for the specific detection of enterovirus (EV) RNA in clinical specimens controlled by an internal control (IC) RNA. The IC RNA contains the same primer binding sites as EV RNA but has a different probe region. The IC RNA was packaged into an MS2 phage core particle (armored) and was added to the clinical sample to allow monitoring of both extraction efficiency and RT-PCR efficiency. Serial dilutions of the IC RNA were made, and the detection limit of the RT-PCR was tested in a background of EV RNA-negative cerebrospinal fluid. The sensitivity and specificity of the RT-PCR assay were tested by using all 64 known EV serotypes, several non-EV serotypes, and two Quality Control for Molecular Diagnostics (QCMD) Program EV proficiency panels from 2001 and 2002. In total, 322 clinical specimens were tested by RT-PCR, and to establish the clinical utility of the RT-PCR, a comparison of the results of viral culture and RT-PCR was done with 87 clinical specimens. The lower limit of sensitivity was reached at about 150 copies of IC RNA/ml. All 64 EV serotypes were positive, while all non-EV serotypes were negative. All culture-positive samples of the 2001 QCMD proficiency panel (according to the 50% tissue culture infective doses per milliliter) were positive by RT-PCR. Invalid results, i.e., negativity for both EV RNA and IC RNA, due to inhibition of RT-PCR were observed for 33.3% of the members of the 2002 QCMD proficiency panel and 3.1% of the clinical specimens. Inhibition of RT-PCR could be relieved by the addition of 400 ng of bovine alpha-casein per microl to both the RT reaction mixture and the PCR mixture. With this optimized protocol, the results for all samples of the 2002 QCMD proficiency panel and all clinical specimens except one fecal sample (0.3%) were valid. Evaluation of the clinical samples demonstrated that EV infection could be detected in 12 of 87 samples (13.8%) by RT-PCR, while viral culture was negative. Our data show that the RT-PCR with armored IC RNA offers a very reliable and rapid diagnostic tool for the detection of EV in clinical specimens and that the addition of bovine alpha-casein relieved inhibition of the RT-PCR for 99.7% of clinical specimens.

Prospective investigation of a large outbreak of meningitis due to echovirus 30 during summer 2000 in marseilles, france

Enteroviruses (EVs) are responsible for an array of clinical diseases affecting different systems of the organism. Many cases are asymptomatic; the most severe clinical syndromes caused by EVs are due to infection of the central nervous system and present as aseptic meningitis or encephalitis. We report here a large outbreak of enteroviral meningitis that spread in Marseilles, France, during the year 2000. The dominant strain of the outbreak was genetically identified as a human echovirus 30. The study was conducted prospectively from May to December 2000, with an investigative protocol recording epidemiologic, clinical, and laboratory data. A total of 250 patients with febrile neurologic manifestations were included between May 15 and December 30, 2000. A total of 195 cerebrospinal fluid (CSF) samples, 114 throat swabs, and 85 stool specimens were processed through viral culture and resulted in respectively 117 (60%), 61 (54%), and 58 (68%) cultures positive for EV; 69/106 (65%) CSF samples tested positive for the presence of EV RNA. None of the throat swab cultures but 5 of the stool cultures in control patients were positive. One hundred thirty-nine (55.6%) patients were considered confirmed cases because they had positive culture or reverse transcription polymerase chain reaction (RT-PCR) in CSF, and 38 (15.2%) patients were considered probable cases because they had a positive throat and/or stool culture and a negative (or not performed) procedure in CSF. The 177 confirmed and probable cases were not significantly different from the remaining 73 patients in terms of age distribution and epidemiologic, clinical, and biologic characteristics. The median age was 18.4 years (range, 15 d to 84 yr), and 92% of patients were younger than 40 years old. The male:female sex ratio was 1.8:1. We found no evidence of cases spread in nosocomial, household, or institutional settings, or limited community spread. All patients were immunocompetent except 4 adults. Meningoencephalitis represented 5.6% of cases. All but 3 of the 177 patients had a good outcome without sequelae. Two immunocompetent adults with meningoencephalitis had neurologic sequelae and an immunosuppressed adult had a fatal outcome. Upper respiratory symptoms were noted in 18.5% of patients, diarrhea in 11.5%, various types of rash in 4.5%, and myalgia in 3.8%. In CSF, white cell count was elevated in 90% of cases, with a percentage of neutrophils >50% in 55% of cases. Protein level was increased in 43% of cases. In blood, C-reactive protein was elevated in 67% of cases. Other blood parameters were unremarkable. Clinical and laboratory features did not differ from those related to other pathogens that caused meningitis and meningoencephalitis. Hence, unnecessary treatment for other infections is frequently instituted during EV infections. Virologic diagnosis is important to distinguish between EV and other treatable bacterial and viral diseases.

New reverse transcription-PCR assay for rapid and sensitive detection of enterovirus genomes in cerebrospinal fluid specimens of patients with aseptic meningitis

Enterovirus (EV) detection by a new commercially available reverse transcription (RT)-PCR assay (Penter RT-PCR test) was compared with EV isolation from cell cultures and with EV detection by an in-house RT-PCR assay. Of the 54 cerebrospinal fluid specimens collected during a summer outbreak of aseptic meningitis, 52% were positive by cell culture versus 76% by in-house RT-PCR assay and 80% by the new RT-PCR test (52 versus 76 versus 80%; P = 0.003). This new reliable EV RNA detection test is suitable for clinical diagnosis of EV-related meningitis and may improve the management of EV-related neurological syndromes.

[Enteroviral meningitis in adults, underestimated illness: description of 30 observations from 1999 to 2000, and evolution of clinical practices during 2001]

Enteroviral meningitis is well documented in children but underestimated in adults. The analysis of 30 cases of adult meningitis prospectively diagnosed by enterovirus genome detection (RT-PCR) in cerebrospinal fluid (CSF) between 1999 and 2000 in routine practice showed diagnosis to be problematic. Characteristic symptoms were inconstant (the association of fever/headache/stiff neck absent in 41%) and sometimes misleading (the presence of peribuccal lesions). CSF data showed a predominance of lymphocytes in only 44% of patients. The most reliable criterion was normal constant CSF glucose levels. Thirty three per cent of patients were admitted during cold months. Management of patients varied markedly between departments, and included computed tomography (33%), and the prescription of aciclovir (20%) or antibiotics (53%). A report of positive enterovirus RT-PCR had only low impact on management because it took 6 days to obtain the results (versus 3 days in children during the same period). These findings were communicated to all hospital physicians concerned and as a result, the number of RT-PCR in adults increased significantly during 2001. Again, enteroviral meningitis was diagnosed in adults despite a much lower incidence of the illness in 2001 compared to 2000. Thus this pathology should not be underestimated in adults. Considerable medical expenditure might be avoided (cumulative numbers of 172 days in hospital and 82 days of antibiotics in this study), if rapid and accurate diagnostic techniques were available.

Fast duplex one-step RT-PCR for rapid differential diagnosis of entero- or toscana virus meningitis

Acute meningitis is the most common neurologic disease that involves the central nervous system. The spectrum of infectious agents that cause neurologic infection is remarkably broad and numerous viruses are the most frequent cause of the aseptic meningitis syndrome. We applied a multiplex one-step method for the rapid detection of the genomic RNA of different neurotropic viruses: particles in the genus Enterovirus and Toscana virus, which are the most representative aetiologic agents in our country during the spring-summer period. We have evaluated the sensitivity and the specificity of the multiplex one-step test on positive controls and on RNA extracted from clinical samples harvested from 475 patients with meningitis hospitalized during the 1996-2001 period. The multiplex one-step RT-nPCR protocol allows for the detection of enterovirus and Toscana virus RNA in a single sample, by using, at the same time, a very small clinical sample volume. In our study we were able to diagnose 192 cases of meningitis by Toscana virus and 31 cases by enteroviruses out of 475 cases of meningitis utilizing the described one-step multiplex method.

Differentiation of Herpes simplex virus types 1 and 2 in sera of patients with HSV central nervous system infections by type-specific enzyme-linked immunosorbent assay

OBJECTIVE

To differentiate by enzyme-linked immunosorbent assay (ELISA) using type-specific glycoprotein G herpes simplex virus (HSV) type 1 and type 2 in serum collected from patients with HSV central nervous system (CNS)infections.

METHODS

HSV 1 and 2 typing in convalescent sera of 17 patients with HSV acute encephalitis, myelitis, or meningitis was determined by the type-specific IgG ELISA kit (Gull Laboratory, Inc.). HSV CNS infections were diagnosed by polymerase chain reaction (PCR) or conventional serologic tests from acute to convalescent stages.

RESULTS

In 13 of 17 patients, HSV type 1 and HSV type 2 antibodies were positive; 11 patients with HSV type 1 and 2 patients with HSV type 2 were found. All 10 patients with encephalitis showed equivocal or positive results for HSVtype 1. In two of three cases of myelitis, HSV type 1 was demonstrated. Each case of myelitis and meningitis reacted to both types 1 and 2.

CONCLUSION

These data suggest that the kit is useful for type differentiation of HSV CNS infections from convalescent sera, and can play a supplementary role in HSV typing by PCR or previous serologic tests.

Non-polio enteroviruses in acute flaccid paralysis

OBJECTIVE

Human enteroviruses are the major cause of aseptic meningitis and also cause a wide range of other acute illnesses, including neonatal sepsis like disease, meningitis, acute flaccid paralysis and acute hemorrhagic conjunctivitis. Infection in neonates is particularly life threatening.

METHODS

Stool samples of 523 children (age < 4 years) showing symptoms of acute flaccid paralysis (AFP) were studied. National Polio Surveillance Project workers from different parts of Uttar Pradesh and Bihar collected the samples during June to October 1998. Non-polio enteroviruses (NPEV) were isolated in 191 cases only, by cell culture based neutralization assay. These NPEV isolates were further studied to find the frequent enterovirus serotype detected in stool of children having AFP.

RESULTS

Data generated will help future studies on NPEV serotypes circulating in this area.

CONCLUSION

In addition it may reduce unnecessary hospitalization, allow immune globulin batches of high titres to frequently circulating serotypes, to be reserved for intravenous therapy of neonates and guide the formulation of antigens for rapid and less expensive diagnosis.

Prospective analysis of 61 cases of enteroviral meningitis: interest of systematic genome detection in cerebrospinal fluid irrespective of cytologic examination results

BACKGROUND

Enteroviruses are the most commonly identified cause of viral meningitis. Detection of the enterovirus genome in cerebrospinal fluid (CSF) using reverse-transcription polymerase chain reaction (PCR) has proved to be useful in diagnosis and is more rapid and sensitive than viral cultures. In routine practice, cytologic examination results of CSF are obtained swiftly and PCR indication is performed as a second step.

OBJECTIVES

The aim of this study was to determine, by analysis of complete data from CSF results for 61 cases of proven enteroviral meningitis, whether cytologic CSF findings can be used to establish viral etiology and to indicate if PCR assay should be performed.

STUDY DESIGN

From a prospective study of children admitted during 1997 for suspected enterovirus meningitis in which PCR and viral cultures of CSF were systematically performed, we selected 61 patients with proven enterovirus meningitis. We compared global white cell count (WCC), relative percentage of lymphocytes/neutrophils, PCR and culture for enterovirus, patient age, and clinical data.

RESULTS

92% of patients (56/61) had positive PCR in CSF and in 48% (29/61) enterovirus was isolated in CSF. Nine patients (14.75%) had WCC<10/mm(3); eight of them had positive PCR and two had positive culture. There were comparable numbers of CSF with a predominance of lymphocytes (n=25) and CSF with a predominance of neutrophils (n=22), and of positive PCR and positive cultures of CSF in the two groups. Results were not influenced by the age of the patients.

CONCLUSION

Irrespective of other CSF parameters, it seems difficult to dispense with PCR assay for enterovirus genome detection. It should be introduced as a true rapid routine test. Early reporting of a positive PCR result could result in a considerable saving in health resources.

Detection of neurotropic viruses circulating in Tuscany: the incisive role of Toscana virus

Acute meningitis is perhaps the most frequent among central nervous system infections. We report a study considering 277 cases of meningitis hospitalized in the southern Tuscany area (Italy) during the period from 1995 to 1998 investigated by tissue culture and polymerase chain reaction (PCR) methods. The cytochemical analysis of the cerebrospinal fluid samples suggested the diagnosis of aseptic meningitis, recognized as viral meningitis in 104 cases by detection of viral DNA or RNA. The results collected by tissue culture technique, available for 95 clinical samples, reported a positive isolation for only 12 cases. The viruses identified in the neurological infection were Toscana virus (81%), enterovirus (12%), mumps virus (3%), measles virus (1%), and herpes virus type 1 (3%). These data demonstrate the incisive role of the RNA viruses as the cause of meningitis, and overall the relevance of Toscana virus.

Amplicor enterovirus polymerase chain reaction in patients with aseptic meningitis: a sensitive test limited by amplification inhibitors

OBJECTIVE

To evaluate the sensitivity and specificity of reverse-transcription polymerase chain reaction (RT-PCR) and routine cell culture for the detection of enterovirus in cerebrospinal fluid.

METHODS

Thirty-eight cerebrospinal fluid specimens were included. Cell culture was inoculated immediately and incubated for 14 days. An aliquot was kept frozen for Amplicor RT-PCR. Chart review was performed to determine the validity of the results.

RESULTS

Nine of 38 specimens were positive for enterovirus by culture, and 14 were positive by RT-PCR. There were 7 discrepancies between the 2 methods. Six specimens were positive by RT-PCR and negative by the culture method. The 1 culture-positive but RT-PCR--negative specimen was determined to contain PCR inhibitors. All discrepant results were confirmed as true positives by chart review. Patients whose cerebrospinal fluid was negative by both methods had a final diagnosis other than enterovirus infection.

CONCLUSION

Amplicor PCR is more sensitive than cell culture (93.3% vs. 60%) and is very specific. With the incorporation of appropriate controls for the detection of amplification inhibitors, RT-PCR could be a valuable tool in the diagnosis of enteroviral meningitis.

Detection by PCR of enteroviruses in cerebrospinal fluid during a summer outbreak of aseptic meningitis in Switzerland

Enteroviruses (EV) are among the most common causes of aseptic meningitis. Standard diagnostic techniques are often too slow and lack sensitivity to be of clinical relevance. EV RNA can be detected within 5 h by a commercially available reverse transcription-PCR (RT-PCR) test kit. Cerebrospinal fluid (CSF) samples from 68 patients presenting with aseptic meningitis during a summer outbreak in Switzerland were examined in parallel with cell culture and commercial RT-PCR. RT-PCR was positive in all 16 CSF specimens positive by cell culture (100%). In addition, 42 of 52 (80%) CSF samples negative by cell culture were PCR positive. In 26 of these 42 (62%) patients, viral culture from other sites (throat swab or stool) was also positive. The CSF virus culture took 3 to 7 days to become positive. Echovirus 30 was the type most often isolated in this outbreak. The sensitivity of CSF RT-PCR based on clinical diagnosis during this aseptic meningitis outbreak in patients with negative bacterial culture results was 85%, i.e., considerably higher than the sensitivity of CSF virus culture (24%). We conclude that this commercial RT-PCR assay allows a positive diagnosis with minimal delay and may thus influence clinical decisions.

Use of monoclonal antibodies to identify serotypes of enterovirus isolates

Nonpoliovirus enteroviruses cause a variety of diseases that are common in young children and adults. The "gold standard" for laboratory diagnosis of enteroviruses is cell culture isolation, followed by serotype identification by neutralization assay. These procedures are time-consuming and expensive. Rapid serotype identification of enteroviruses is important in differentiating nonpoliovirus enterovirus pathogens from vaccine strain polioviruses that can be shed for some time after vaccination. In the present investigation, we evaluated a rapid method for serotype identification of enteroviruses by indirect immunofluorescence assay (IFA) using commercially available monoclonal antibodies for polioviruses, coxsackieviruses type B, and six serotypes of commonly circulating echoviruses. Of 291 isolates of enteroviruses included in the study, 95 were polioviruses and 196 were nonpoliovirus enteroviruses. Two hundred thirty-four of these (38 polioviruses and 196 nonpoliovirus enteroviruses) were consecutively grown in the laboratory over a 5-year period. IFA identified the serotypes of 74% of the consecutive isolates and 71% of all enterovirus isolates by yielding a positive staining result. The levels of agreement in the identification of the enterovirus group between IFA and neutralization tests were 92% for consecutively grown isolates and 85% for all enterovirus isolates. The sensitivity of the IFA for the detection of viruses for which specific monoclonal antibodies were applied was 73% for polioviruses, 85% for coxsackieviruses type B, and 94% for echoviruses. Specificity was near 100% for polioviruses and coxsackieviruses type B and 94% for echoviruses. We conclude that IFA can be helpful as a preliminary test for serotype identification of enteroviruses. The results are most accurate when the test identifies the isolate as a poliovirus.

Evaluation of a commercially available reverse transcription-PCR assay for diagnosis of enteroviral infection in archival and prospectively collected cerebrospinal fluid specimens

A commercially available reverse transcription (RT)-PCR method (AMPLICOR EV; Roche Diagnostic Systems, Inc., Branchburg, N.J.) was evaluated for detection of enteroviruses in cerebrospinal fluid from patients with neurological disease. This assay was compared with virus isolation in cell culture and an in-house RT-PCR method designed with a nonoverlapping region of the enteroviral genome. A panel of 200 cerebrospinal fluid specimens prospectively collected from patients with a wide variety of neurological symptoms, including 50 patients involved in three different outbreaks of acute aseptic meningitis, was assayed. A second panel of 97 archived cerebrospinal fluid specimens, stored for 2 to 5 years, from patients with aseptic meningitis associated with several enterovirus outbreaks was also studied. From the first panel, enteroviruses were detected in 13 of 50 specimens by cell culture (26%), in 43 of 50 specimens by AMPLICOR EV (86%), and in 46 of 50 specimens by the in-house assay (92%) from patients with aseptic meningitis associated with outbreak and 1 of 29, 3 of 29, and 4 of 29 specimens, respectively, from sporadic cases of aseptic meningitis. The remaining 121 cerebrospinal fluid specimens from patients with other neurological syndromes were negative by all tests. From the second panel, enteroviral RNA was detected by the AMPLICOR test (31 of 97 specimens, 32%) and the in-house assay (39 of 97 specimens, 40%). According to our results, patients with aseptic meningitis should be analyzed for enteroviral infection in cerebrospinal fluid by RT-PCR methods, and the AMPLICOR EV test is a suitable tool for performing such studies. Archival cerebrospinal fluid specimens are less suitable for evaluation of the performance of RT-PCR methods designed for enterovirus detection.

Molecular typing of enteroviruses: current status and future requirements. The European Union Concerted Action on Virus Meningitis and Encephalitis

Human enteroviruses have traditionally been typed according to neutralization serotype. This procedure is limited by the difficulty in culturing some enteroviruses, the availability of antisera for serotyping, and the cost and technical complexity of serotyping procedures. Furthermore, the impact of information derived from enterovirus serotyping is generally perceived to be low. Enteroviruses are now increasingly being detected by PCR rather than by culture. Classical typing methods will therefore no longer be possible in most instances. An alternative means of enterovirus typing, employing PCR in conjunction with molecular genetic techniques such as nucleotide sequencing or nucleic acid hybridization, would complement molecular diagnosis, may overcome some of the problems associated with serotyping, and would provide additional information regarding the epidemiology and biological properties of enteroviruses. We argue the case for developing a molecular typing system, discuss the genetic basis of such a system, review the literature describing attempts to identify or classify enteroviruses by molecular methods, and suggest ways in which the goal of molecular typing may be realized.

Aseptic meningitis: a seasonal concern

Outbreaks of aseptic meningitis-like illnesses have occurred in high school football players for reasons that may include the close contact among players and the overlap of football season with the peak enterovirus season. The main symptoms are fever, headache, and neck or back stiffness; physical findings may include signs of meningeal irritation. Evaluation of the cerebrospinal fluid can confirm the diagnosis. Treatment of viral meningitis is generally supportive, and patients usually do well, while other forms of aseptic meningitis may require drug treatment or removal of inciting medications. Not sharing water bottles may help reduce risk.

Rapid diagnosis of enterovirus infection by a new one-step reverse transcription-PCR assay

The AMPLICOR Enterovirus Test was evaluated with 103 cerebrospinal fluid (CSF) specimens. Twenty-seven CSF specimens were culture positive. With the AMPLICOR test, enterovirus RNA was detected in 34 specimens. Compared with culture, the AMPLICOR test gave a sensitivity of 96.3% and a specificity of 100%. The sensitivity of culture was 79.4% in comparison with the AMPLICOR test.

Aseptic meningitis and encephalitis: the role of PCR in the diagnostic laboratory

In this study we have devised a simple and robust PCR strategy to detect a wide range of viruses, bacteria, and parasites, all of which are capable of causing aseptic meningitis and encephalitis. The techniques developed have been used in a routine diagnostic virology laboratory to test prospectively 2,233 cerebrospinal fluid specimens. A virus was detected in 147 specimens of cerebrospinal fluid from 143 patients. Four sets of primers were sufficient to detect the virus in 135 (94%) of the PCR-positive patients. We conclude that with appropriate primers, PCR can be systematically and economically applied to test for a range of organisms in a routine diagnostic laboratory. In our opinion, PCR will soon become the "gold standard" test for viral infections of the central nervous system.

Viral meningitis due to echovirus types 6 and 9: epidemiological data from Western Australia

During the autumn of 1992, Western Australia experienced a large viral meningitis outbreak of dual aetiology. Of the 161 cases, 64% were children under 15 years of age, with the highest notification rate being in children less than 5 years of age. Echovirus 9 caused 41% of cases and occurred mainly in the metropolitan areas of Western Australia whereas echovirus 6, which caused 37% of cases, was more widespread. An enterovirus was cultured from 70% of CSF specimens, 88% of faecal specimens and 68% of upper respiratory tract specimens. High CSF white cell counts and neutrophil predominance were common. Seven cases had normal CSF white cell counts even though an enterovirus was isolated from the CSF. Therefore, the CSF findings were of restricted value in excluding viral meningitis, and did not reliably distinguish between bacterial and viral meningitis.

Survey of herpes simplex virus infections of the central nervous system, including acute disseminated encephalomyelitis, in the Kyushu and Okinawa regions of Japan

We analysed data from 27 patients with herpes simplex virus (HSV) infections of the central nervous system (CNS) found in a 1990-1992 survey in Kyushu and Okinawa, Japan. Patients ranged in age from one year to 70 years, with peaks seen in the 20s and 50s. Temporal lobe-limbic encephalitis was the most common HSV infection (13 patients), followed by meningitis (5), diffuse encephalitis (4), disseminated encephalomyelitis (ADEM) (3) and brain stem encephalitis (2). Another three patients with non-herpetic, non-paraneoplastic acute limbic encephalitis were presented. Our study indicates that HSV infection can course ADEM, although temporal lobe-limbic encephalitis or meningitis are more common. The early diagnosis of HSV-related ADEM is important because of the efficacy of the timely administration of corticosteroids.

Cerebrospinal fluid values in the term neonate

BACKGROUND

Cerebrospinal fluid (CSF) values in the noninfected neonate are not well-delineated. Studies analyzing these values are inconsistent in the criteria used to define the noninfected population. The purpose of our study was to examine CSF values in neonates in the first 30 days of life in whom infection was more thoroughly excluded than in previous reports. Stringent inclusion criteria defined the noninfected population, and the recently available polymerase chain reaction (PCR) for enteroviruses was used in addition to cultures to help exclude viral disease. Results were also stratified by age in weeks to evaluate for any variability that occurs in CSF values during the first month of life.

METHODS

Neonates were selected from subjects enrolled in two studies on aseptic meningitis. Noninfected infants were identified by the following criteria: (1) atraumatic lumbar puncture (< or = 1000 red blood cells/mm3); (2) no antibiotic therapy before lumbar puncture; (3) sterile blood, CSF and urine bacterial cultures; (4) negative CSF viral culture; and (5) negative CSF PCR for enteroviruses.

RESULTS

The mean +/- SD total CSF white blood cell count for 108 noninfected neonates was 7.3 +/- 14/mm3 (95% confidence interval 6.6 to 8.0/mm3) with a median of 4/mm3 and a range of 0 to 130/mm3. There were no significant differences in the mean CSF white blood cell counts among age categories.

CONCLUSIONS

The application of stringent inclusion criteria and the use of the PCR yielded a population of infants that better represents the noninfected neonate than earlier reports. These values can be used for reference in evaluating the febrile or ill neonate.

Acute meningitis of unknown aetiology: analysis of 219 cases admitted to hospital between 1977 and 1990

Clinical and biochemical parameters in 219 patients with meningitis of unknown aetiology were analyzed according to their initial CSF leucocyte count. The male/female ratio was 1.1 and the median age 30 years,(males = 22 years/females = 42 years). Pre-admission antibiotic, which may inhibit bacterial growth, was given to 28% patients. On admission symptoms of meningitis were predominant: 96% had fever, 91% neck rigidity and 19% a severely affected mental state. In addition, 10% had a petechial rash. A bacterial aetiology was likely, as 91% had a predominance of polymorphonuclear leucocytes in the CSF and in 50% it was frankly purulent. The CSF leucocyte count correlated positively with age, the period of fever and the length of hospitalization, but did not relate to the 10.1% in-patient mortality rate. Mortality was related to advancing age, but not to the antibiotic regimen chosen. Patients admitted directly from their homes had the least complicated disease course and all survived. A low CSF leucocyte count, mainly found in young patients so admitted, could indicate either a non-bacterial self-limiting aetiology or diagnosis at an early stage of the disease. We found, however, that bacterial meningitis cannot be excluded on the basis of the CSF leucocyte count in combination with any clinical and biochemical parameters. Rapid hospital admission, regardless of age, is of major importance for prognosis. Improvement of non-cultural diagnostics tests and adjunctive therapy regimens are essential.

Direct and uninterrupted RNA amplification of enteroviruses with colorimetric microwell detection

BACKGROUND

Enteroviruses (EV) cause a broad spectrum of human diseases, of which aseptic meningitis is among the most common and most clinically vexing. While the clinical symptoms of meningitis caused by bacteria, fungi and viruses are similar, the diagnosis, therapy and outcome of disease caused by these agents vary greatly. In order to appropriately manage meningitis patients, rapid and reliable diagnosis of EV meningitis impacts significantly on patient management.

OBJECTIVE

To develop a direct and uninterrupted RNA amplification of enteroviruses using rTth DNA polymerase.

STUDY DESIGN

Purified coxsackievirus B6 RNA of various concentrations was amplified by rTth DNA polymerase-mediated amplification to determine analytic sensitivity. The specificity of the EV amplification was examined with a panel of nucleic acids from 36 EV serotypes, 15 non-EV pathogens and 10 coded clinical specimens of cerebrospinal fluid (CSF).

RESULTS

All EV serotypes tested were detected successfully by this method at a sensitivity of 1 TCID(50) with the exception of echoviruses 1, 5, 22 and 23. Echovirus 5 was detected at 10 TCID(50), and echovirus 1 was detected at 100 TCID(50). Echoviruses 22 and 23 were not detectable at 100 TCID(50). Cross-reactivity of EV RT-PCR assay with 15 known non-EV meningitis pathogens has not been observed. Results of 10 CSF tested with this system correlated well with tissue culture.

CONCLUSIONS

We have developed an EV amplification assay which has several important advantages over previously reported methods. This assay employs rTth DNA polymerase which possesses both reverse transcriptase and DNA polymerase activities, simplifying RNA reverse transcription and DNA amplification to an uninterrupted reaction. Additionally, potential carryover contamination and enhanced amplification specificity is provided by substituting dUTP for dTTP and adding uracil N-glycosylase (UNG) in the amplification reaction. Finally, the detection of amplified product is via a colorimetric, microwell format permitting the use of readily available instrumentation.

Use of laboratory testing for genital chlamydial infection in Norway

OBJECTIVE

To assess the use of laboratory tests for genital chlamydial infection in Norway.

DESIGN

Questionnaire survey of general practitioners' practice in chlamydial testing, retrospective survey of laboratory records, 1986-91, and prospective study of testing in one laboratory during four weeks.

SETTING

All 18 microbiological laboratories in Norway (4.2 million population), including one serving all doctors in Vestfold county (0.2 million population).

SUBJECTS

302 general practitioners.

MAIN MEASURES

GPs' routine practice, methods used for testing, 1986-91, and sex specific and age group specific testing in 1991.

RESULTS

201(69%) GPs replied to the questionnaire: 101(51%) would test all women younger than 25 years at routine pelvic examination, 107(54%) all girls at first pelvic examination, 131(66%) all pregnant women, and 106(54%) all men whose female partner had urogenital complaints. Nationwide in 1986, 122,000 tests were performed (2.9 per 100 population); 10% were positive and 51% were cell culture tests. In 1991, 341,000 tests were performed (8.0 per 100 population); 4.5% were positive and 15% were cell culture tests. 13,184 tests were performed in Vestfold in 1991 (6.6 per 100 population). The age group specific rates (per 100 population) among women were: age 15-19 years, 22.0(95% confidence interval 18.2 to 25.8); 20-24 years, 47.2(42.1 to 52.3); 25-29 years, 42.3(37.1 to 47.5); 30-34 years, 29.8(25.4 to 34.2); and 35-39 years, 12.5(9.5 to 15.5).

CONCLUSIONS

GPs use liberal indications for testing. The dramatic increase in testing, especially by enzyme immunoassays, in populations with a low prevalence of infection results in low cost effectiveness and low predictive value of positive tests, which in women over 29 years is estimated as 17-36%.

IMPLICATIONS

Doctors should be educated about the limitations of enzyme immunoassays in screening low prevalence populations, and laboratories should apply a confirmatory test to specimens testing positive with such assays.

Suspect value of non-CSF viral cultures in the diagnosis of enteroviral CNS infection in young infants

Laboratory criteria used for presumptive diagnosis of enteroviral meningitis were evaluated as predictors of cerebrospinal fluid (CSF) infection. Records were retrospectively analysed of infants under four months of age admitted to hospital between 1977 and 1987 with viral CSF cultures: those with enteroviruses isolated from CSF (group 1) were compared with those with enteroviruses isolated only from non-CSF sites (group 2). Predictive value computations demonstrated that no single or combined non-CSF culture accurately predicted isolation of enteroviruses from the CSF. These results suggest that CSF viral culture is imperative in establishing the diagnosis of enteroviral meningitis in young infants.

Laboratory diagnosis of bacterial meningitis

Bacterial meningitis is relatively common, can progress rapidly, and can result in death or permanent debilitation. This infection justifiably elicits strong emotional reactions and, hopefully, immediate medical intervention. This review is a brief presentation of the pathogenesis of bacterial meningitis and a review of current knowledge, literature, and recommendations on the subject of laboratory diagnosis of bacterial meningitis. Those who work in clinical microbiology laboratories should be familiar with the tests used in detecting bacteria and bacterial antigens in cerebrospinal fluid (CSF) and should always have the utmost appreciation for the fact that results of such tests must always be reported immediately. Academic and practical aspects of the laboratory diagnosis of bacterial meningitis presented in this review include the following: anatomy of the meninges; pathogenesis; changes in the composition of CSF; etiological agents; processing CSF; microscopic examination of CSF; culturing CSF; methods of detecting bacterial antigens and bacterial components in CSF (counter-immunoelectrophoresis, coagglutination, latex agglutination, enzyme-linked immunosorbent assay, Limulus amebocyte lysate assay, and gas-liquid chromatography); use of the polymerase chain reaction; and practical considerations for testing CSF for bacterial antigens.

Parainfluenza type 3 meningitis. Report of two cases and review of the literature

The authors present two immunocompetent children with parainfluenza type 3 meningitis. In each case, the outcome was favorable without detectable complications. The authors reviewed the literature, showing that central nervous system (CNS) involvement by parainfluenza viruses has rarely been described but may present with a variety of neurologic syndromes. Pediatricians and laboratory personnel should recognize that these viruses, commonly known to produce respiratory syndromes, can also be a cause of CNS infections. If additional studies confirm these observations, clinicians and virology laboratories may consider whether early hemadsorption testing to detect myxoviruses is warranted.