Serious infections of the central nervous system: encephalitis, meningitis, and brain abscess

Central nervous system infections in adolescents range from the diffuse cerebritis of encephalitis to the regional inflammation of meningitis, and very focal disease of brain abscess. Clinical presentations reflect this wide spectrum, with encephalitis primarily characterized by altered mental status, meningitis by fever, headache, and neck stiffness, and brain abscess manifesting localizing findings. Encephalitis and viral meningitis are frequently caused by the seasonal enteroviruses and arboviruses, while most adolescent bacterial meningitis is due to Neisseria meningitidis and Streptococcus pneumoniae. The microbiology of brain abscess reflects underlying host risk factors. Gram-positive cocci are seen in patients with congenital heart disease, while respiratory flora including anaerobes are associated with sinus or otic disease. Lumbar puncture to characterize and culture the CSF remains the optimal test for the diagnosis and management of encephalitis and meningitis, while CT-guided needle biopsy may be both diagnostic and therapeutic for brain abscesses. New diagnostic tests include the use of PCR. A variety of safe and effective treatment regimens exists for most bacterial infections as well as for some herpesvirus infections. New vaccines are under study to further control bacterial meningitis.

Validation of a diagnosis model for differentiating bacterial from viral meningitis in infants and children under 3.5 years of age

The aim of this study was to validate, in a population of infants and children under 3.5 years of age, a diagnosis model that provides a figure for the probability of bacterial meningitis (pABM), based on four parameters collected at the time of the first lumbar tap: the cerebrospinal fluid (CSF) protein level, CSF polymorphonuclear cell count, blood glucose level, and leucocyte count. The best cut-off value for distinguishing between bacterial and viral meningitis was previously found to be 0.1, since 99% of meningitides associated with pABM<0.1 were viral. The charts of 103 consecutive children aged 0.1-3.5 years who had been hospitalised for acute meningitis were reviewed. Each case was sorted into the following three categories for aetiology: bacterial (positive CSF culture, n=48); viral (negative CSF culture and no other aetiology, and no antibiotic treatment after diagnosis, n=36); and undetermined (fitting neither of the first two definitions, n=19). After computation of pABM values in each case, the predictive values of the model were calculated for different pABM cut-off values. The results confirmed that the best cut-off pABM value was 0.1, for which the positive and negative predictive values in this model were 96% and 97%, respectively. Only one case of bacterial meningitis (lumbar tap performed early in an infant with meningococcal purpura fulminans with negative CSF culture) was associated with a pABM value of <0.1. This model is quite reliable for differentiating between bacterial and viral meningitis in children under 3.5 years of age, and it may enable physicians to withhold antibiotics in cases of meningitis of uncertain aetiology.

Outbreak of Orthoreovirus-induced meningoencephalomyelitis in baboons

BACKGROUND AND PURPOSE

Spontaneous viral encephalitis is rare in the baboon; yet, during a 13-month period (1993-1994), eight juvenile baboons (Papio cynocephalus spp.) developed acute, progressive nonsuppurative meningoencephalomyelitis caused by an unknown agent. Clinical signs of disease included disorientation and truncal ataxia that rapidly progressed to hemiparesis or paraparesis. Clinicopathologic findings were not remarkable and appreciable gross lesions were not seen at necropsy. Microscopic examination revealed CNS lesions that were characterized by lymphoplasmacytic perivascular cuffing, microglial nodules, demyelination, axonal degeneration, vacuolization, and hemorrhage. Subsequently, a novel syncytium-inducing mammalian orthoreovirus was isolated from the brain tissue of five baboons with clinical signs of infection.

METHODS

To confirm the etiologic role of the orthoreovirus, two juvenile baboons were inoculated with the virus, then were monitored for 6 weeks.

RESULTS

Lesions similar to those seen in spontaneous cases were found in the CNS, and orthoreovirus was isolated from the brain of both animals.

CONCLUSION

Analysis of the outbreak indicated juvenile baboons were most susceptible to disease and the virus had a possible incubation time of 46 to 66 days, but did not indicate a source of the virus or mode of transmission.

[Rapid diagnosis of the type of meningitis (bacterial or viral) by the assay of serum procalcitonin]

OBJECTIVE

It has been shown that serum procalcitonin (PCT) can be used to differentiate bacterial from viral meningitis in children in all cases. The aim of this study was to demonstrate the interest of PCT in the management of suspected meningitis in adults.

PATIENTS AND METHODS

We conducted a prospective study including 179 consecutive patients admitted to the emergency department for suspected meningitis. All samples were taken at patient admission. The discriminant potential between bacterial and viral meningitis was studied for cerebrospinal fluid parameters (cytology, protein, glucose, lactate) and serum parameters (C reactive protein, PCT).

RESULTS

Thirty-two patients had bacterial meningitis, 90 had viral meningitis and meningitis was ruled out in 57. Among all studied parameters, the most discriminant for distinguishing between bacterial and viral meningitis in 100% of the cases proved to be serum procalcitonin with a threshold value of 0.93 ng/ml.

CONCLUSION

Serum procalcitonin is an interesting parameter in the emergency department for management of meningitis suspicion in adults.

Neurotrophin-3 levels in cerebrospinal fluid from children with bacterial meningitis, viral meningitis, or encephalitis

Neurotrophin-3 levels were measured in the cerebrospinal fluid of 35 patients with bacterial meningitis, viral meningitis, or encephalitis by two-site enzyme immunoassay. Elevated cerebrospinal fluid levels of neurotrophin-3 were demonstrated in 8 of 18 patients with bacterial meningitis. Follow-up examination of the eight patients at the convalescent stage showed diminished cerebrospinal fluid levels of neurotrophin-3. In contrast, none of the 17 patients with viral meningitis or encephalitis showed an elevation of neurotrophin-3 levels in cerebrospinal fluid. No relationships were observed between neurotrophin-3 levels and cerebrospinal fluid cell numbers, cerebrospinal fluid protein levels, serum C-reactive protein concentrations, or outcome in bacterial meningitis. Since neurotrophin-3 is involved in the survival of neurons and the modulation of the immune system, neurotrophin-3 could play a neuroprotective or immunomodulatory role in bacterial meningitis.

Identification of resource use and associated costs for viral meningitis

PURPOSE

This study involved identifying resource use and assigning monetary value to the diagnostic work-up and management of viral meningitis.

METHODOLOGY

Using a previously established decision analytic framework, various resources were identified as part of routine management of viral meningitis. Secondary database analyses were used to quantify resources and assign a monetary value as a part of routine management of viral meningitis requiring use of the resource units identified in the decision analytic framework. Discharge data sources from the states of California, Florida, and Illinois, and Medicaid data sources from the state of Pennsylvania, were used for the purpose of analysis.

PRINCIPAL FINDINGS

Physician visits, emergency room visits, hospital admissions, procedures, and medications were identified as the major resource used. Lumbar punctures, CT scans, and antibiotics were identified as the major procedures and medications utilized. No significant difference was found in the major resources used between the states' discharge data and the Medicaid data sources. The mean total charges for patient admissions with CT scans were significantly higher than for patient admissions without CT scans ($11,531.80 vs $7,841.30, P < 0.05). The mean lengths of stay for patients with CT scan were significantly higher than for patient admissions without CT scans (4.71 days vs. 3.88 days, P < 0.05). The patient readmission rate was 10.7 percent, while the readmission rate for episodes with more than one hospitalization was 11.1 percent. The mean charge associated with readmission was $12,200.

The first report on human cases serologically diagnosed as Japanese encephalitis in Indonesia

Although Japanese encephalitis (JE) virus was isolated from mosquitos in 1974, human JE cases have never been reported in Indonesia in spite of the prevalence of anti-JE antibodies among human and pig populations as well as abundant JE vector mosquitos. In this report, we describe serological diagnosis of JE cases in Bali. Indonesia. using IgM-capture ELISA both on serum and cerebrospinal fluid (CSF) of the patients. In the first series of our investigation (Series 1), we examined serum specimens from 12 patients with clinical diagnosis of viral encephalitis, meningitis or dengue hemorrhagic fever (DHF), and found 2 possible JE cases. In the next series (Series 2), we examined both serum and CSF from encephalitis patients and gave laboratory diagnosis of JE. One of them was suspected to have concomitant or recent infection with dengue virus, probably type 3. These results strongly indicated that JE has been prevalent in Bali, Indonesia.

[Etiologic diagnosis of viral meningitis. Study of 142 cases]

Viral meningitis is a common disease, most often benign and striking predominantly children. In 1997, there was an outbreak of viral meningitis in the North of Portugal and this pathology accounted for 496 admissions to the Infectious Diseases Department of S. João Hospital. The authors' aim was to determine the etiology of the cases of viral meningitis admitted to the S. João Hospital by, in a first phase, searching enterovirus and serology for mumps in a sample of 142 patients with symptoms, signs and cerebrospinal fluid (CSF) cytochemical abnormalities typical of viral meningitis, in the absence of any bacterial or fungal growth (in blood and/or CSF) and with negative soluble bacterial antigens in CSF. The enterovirus was detected by polymerase chain reaction (PCR) and, in a small number of cases, by shell vial culture. The diagnosis of mumps was made by the detection of specific IgM antibodies in serum, using an enzyme-linked immunosorbent assay. The diagnosis was reached in 70 patients (49.3%): 47 (33.1%) had mumps meningitis and 23 (16.2%) enterovirus infection (PCR positive in all; culture positive in only 2 cases). In 72 patients (50.7%), the agent was not identified. Although only two agents were searched for, the diagnosis was made in a high proportion of cases. The culture method used for the isolation of enterovirus was found to have a low sensitivity.

Meningitis: causes, symptoms and signs and nursing management

This article discusses the infectious disease meningitis--a notifiable disease since 1912 (Payling, 1994). The major concern is bacterial meningitis and in particular the meningococcal cause. Viral meningitis is also considered. Some 50% of cases of meningitis in the UK are of the viral kind, where the patient usually makes a full recovery and in some instances may not be aware of having contracted the disease (Payling, 1994). Cases of bacterial meningitis are few and if treated effectively and with urgency can result in full recovery; however, any delay may result in fatal sequelae. Bacterial meningitis occurs mainly as a result of meningococcal, pneumococcal or Haemophilus influenzae type B (Hib) infection. The latter has largely been eradicated in England and Wales as a result of effective immunization programmes. The nurse must develop an awareness of the disease, and diagnose it at an early stage. He/she should know the procedures for referring the patient to prevent an escalation of the infection and to reduce the severity of its effects.

[A prospective study of meningitis diagnosed in a 3rd-level hospital during a 1-year period]

OBJECTIVE

One-year prospective observational study of meningitis diagnosed at a third level hospital.

PATIENTS AND METHODS

All patients with a cerebrospinal fluid (CSF) specimen with cyto-biochemical characteristics and clinical picture consistent with meningitis were included in the study. They were followed from admission to hospital up to discharge or exitus. The epidemiologic characteristics of patients, etiology, related risk factors and predisposing situations, CSF characteristics, clinical manifestations, clinical course, and antibiotic susceptibility of the causative agents were analyzed.

RESULTS

Ninety-five cases were included. Seventy-six (69.4%) were community acquired and 29 (30.5%) nosocomially acquired meningitis. Among community acquired meningitis, 31 (46.9%) were of bacterial origin (8 N. meningitidis, 3 H. influenzae, 2 S. pneumoniae, 1 Streptococcus group B, 1 Listeria monocytogenes, 1 Staphylococcus aureus, and 1 Brucella spp.); CSF culture was negative in 14 cases (41.2%). In most cases neither risk factor nor predisposing situations were detected. Patients with purulent meningitis and negative CSF culture had a significantly lower number of complications than patients with positive CSF culture. Among patients previously treated with beta-lactam antibiotics (8 cases) the probability of a negative CSF culture was greater than among not treated patients (OR 16.00, 95% CI 1.45-764.68; p = 0.011). The remaining cyto-biochemical characteristics were similar in both groups. Thirty-five cases (53.03%) of community acquisition were lymphocytic meningitis (31 viral, 3 tuberculous, and 1 luetic meningitis). Among nosocomial cases (29 cases, 30.5%), most were caused by gram-negative bacilli and microorganisms of the Staphylococcus genus. Fourteen cases (48.2%) were related to some type of neurosurgical procedure. Overall, only two exitus cases were recorded.

CONCLUSIONS

The etiologic agents of community acquired meningitis are mainly N. meningitidis, S. pneumoniae and Haemophilus influenzae. The previous antibiotic therapy did not influence thy cyto-biochemical characteristics of CSF but it did influence the yielding of culture. Meningitis with negative CSF culture has a significantly lower number of complications. The availability of a Neurosurgery Department at a hospital confers a change in the epidemiologic spectrum of diagnosed meningitis, with a higher incidence of nosocomial meningitis. In our environment, a substantial proportion of cases due to Staphylococcus microorganisms was observed.

An outbreak due to echovirus type 30 in a neonatal unit in France in 1997: usefulness of PCR diagnosis

Between February and August 1997, 53 patients with enterovirus meningitis were hospitalized in Clermont-Ferrand, France. All but one were children. Echovirus type 30 was involved in 70% of cases with identified serotype. The outbreak ceased on August 8. Two months later, a neonate was admitted to the neonatal unit with an echovirus type 30 meningitis thought to be acquired at delivery. Twenty days later a nosocomial outbreak of echovirus type 30 involving five neonates occurred. Two of them presented with meningitis and two with febrile seizure; One was asymptomatic. The retrospective examination of the maternal sera in a neutralization test, using the index case strain as a source of antigen, showed that none of the neonates was passively immunized before hospitalization. The use of genome detection in cerebrospinal fluid allowed rapid diagnosis and infection was contained by re-inforcing hygiene measures. Prospective examination of stools in the neonatal and paediatric units showed no further occurrences of the disease. No sporadic case was observed in the general population. Hence, nosocomial infections can occur a long time after an outbreak in the general population; rapid diagnosis with molecular tools is useful both for a definite diagnosis in patients already hospitalized, and to act as a rapid alert, even in intervals between seasonal outbreaks.

[Enterovirus diagnosis is important, but should be used cautiously]

While the enterovirus diagnostic test positive rate is very low in Sweden, many enterovirus diagnoses are probably missed, owing to inappropriate testing, in patients with acute aseptic meningitis. In the article it is recommended that the cerebrospinal fluid PCR (polymerase chain reaction) test should be performed routinely in cases of acute aseptic meningitis. Serology and virus isolation in stool are indicated in cases of acute pericarditis or myocarditis, or certain chronic heart diseases. The PCR test should be performed in serum in the few cases of sepsis-like diseases in newborns or patients with hypogammaglobulinaemia. Otherwise, enterovirus diagnosis is very seldom justified on clinical grounds. For the purpose of poliovirus surveillance, enterovirus isolation may be important for virus typing, especially in cases of paralytic conditions.

[The use of a modified complement fixation reaction for the rapid diagnosis of viral infections in children]

A system of diagnostic tests (complement enzyme assay) is developed, detecting viral and other antigens, toxins, antibodies, and specific immune complexes in liquid enzyme immunoassay based on the complement fixation test. The system is simple and economic, the results can be transferred into digital data, and the above factors can be detected individually in biological materials from patients. The system is effective, and in many cases (for example, in the diagnosis of enteroviral diseases) is the only method for rapid isolation and typing of the infection agents.

Clinical utility of polymerase chain reaction testing for enteroviral meningitis

BACKGROUND

During summer enteroviral meningitis is a common cause of febrile illness in children, who are typically hospitalized for 2 to 3 days if bacterial infection is suspected. It has been hypothesized that a sensitive polymerase chain reaction (PCR) assay could quickly confirm the diagnosis and subsequently decrease hospitalization costs. However, to have maximum impact results should be available within 24 h. This necessitates daily assays on small numbers of samples.

METHODS

We examined the clinical utility of a PCR assay during two summers, comparing length of stay and charges. Only during the second summer were results reported to clinicians. Case controls were patients with negative PCR assay results but uncomplicated, presumed viral infections. We determined the cost per case identified with and without pleocytosis as a screen for PCR testing.

RESULTS

During the first summer 25% (5/20) of patients with positive PCR assay results remained hospitalized for >2 days. During the second summer 10.2% (6 of 59) of children with positive enteroviral PCR assay results but 37.9% (25 of 66) of case controls remained hospitalized for >2 days. The mean length of hospitalization was significantly (P < 0.05) shorter for patients with positive PCR test results than for case controls. The material cost was approximately $238 per case identified.

CONCLUSIONS

PCR testing has clinical utility for diagnosis of enteroviral meningitis. Although the demands for daily testing make the test expensive, it appears to be cost-effective with savings related to shorter hospital stays.

High sensitivity and specificity of serum procalcitonin levels in adults with bacterial meningitis

It was shown in children that serum procalcitonin was the best marker to use to differentiate bacterial from viral meningitis. To evaluate procalcitonin in the diagnosis of acute bacterial and viral meningitis, we conducted a prospective study including adult patients who were suspected of having meningitis and who were admitted to an emergency department. Cerebrospinal fluid (CSF) and serum levels of procalcitonin were measured in 105 consecutive patients. The diagnosis of meningitis was based on clinical findings, gram staining, culture, and chemical analysis of CSF. Twenty-three patients had bacterial meningitis, 57 had viral meningitis, and 25 did not have meningitis. Bacteriologic and chemical analysis of CSF did not allow correct differentiation of viral from bacterial meningitis. On the other hand, a serum procalcitonin level >0.2 ng/mL had a sensitivity and specificity of up to 100% in the diagnosis of bacterial meningitis. Serum procalcitonin levels seem to be the best marker in differentiating between bacterial and viral meningitis in adults.

C-reactive protein is useful in distinguishing Gram stain-negative bacterial meningitis from viral meningitis in children

OBJECTIVE

To clarify to what extent Gram stain-negative bacterial meningitis can be distinguished from viral meningitis by assessment of cerebrospinal fluid (CSF) and blood indices and serum C-reactive protein (CRP) in children over 3 months of age.

DESIGN

Common CSF indices, blood leukocyte counts, and serum CRP values were compared between patients with bacterial meningitis who had a positive CSF bacterial culture but a negative Gram stain and patients with viral meningitis.

POPULATION

Three hundred twenty-five consecutive patients with CSF culture-proven bacterial meningitis, for whom Gram stain was negative in 55 cases, and 182 children with proven or presumed viral meningitis.

RESULTS

Significant differences between patients with bacterial and viral meningitis were found in all indices with large overlap in all except serum CRP. In patients with bacterial meningitis, the mean CSF glucose concentration, protein concentration, leukocyte count, blood leukocyte count, and serum CRP were 2.9 mmol/L (52 mg/dL), 1.88 g/L, 4540 x 10(6)/L, 18.0 x 10(9)/L, and 115 mg/L; and in those with viral meningitis, mean values were 3.3 mmol/L (59 mg/dL), 0.52 g/L, 240 x 10(6)/L, 10.6 x 10(9)/L, and <20 mg/L, respectively. Of the tests investigated in this study, only serum CRP was capable of distinguishing Gram stain-negative bacterial meningitis from viral meningitis on admission with high sensitivity (96%), high specificity (93%), and high negative predictive value (99%).

CONCLUSION

Exclusion of bacterial meningitis with only the conventional tests is difficult. Combined with careful physical examination and CSF analyses, serum CRP measurement affords substantial aid.

Characterization of Lyme meningitis and comparison with viral meningitis in children

OBJECTIVES

The objectives of this study were to characterize Lyme meningitis (LM) in the pediatric population; to compare LM with viral meningitis (VM) with respect to epidemiology, history and physical examination, and laboratory data; and to provide means of early distinction of Lyme neuroborreliosis from other forms of aseptic meningitis.

METHODS

This retrospective analysis involved children admitted to Alfred I. duPont Hospital for Children between 1990 and 1996 whose discharge diagnoses indicated viral or aseptic meningitis or Lyme disease. LM was defined as the presence of cerebrospinal fluid (CSF) pleocytosis with positive Lyme serology and/or erythema migrans. Patients were considered to have VM if they exhibited CSF pleocytosis and had a positive viral culture. Demographic, clinical, and laboratory data were collected for each patient, and patients with LM were compared with age-matched patients with VM.

RESULTS

Of 179 patient records, 12 patients with LM and 10 patients with VM (all, >2 years old) were identified by using the above criteria. In comparing LM patients with VM patients, we noted no differences among demographic variables. Children with LM had significantly lower temperatures at the time of presentation. The presence of headache, neck pain, and malaise was similar for the two groups, but the duration of these symptoms was significantly longer among LM patients. Five children with LM had cranial neuropathies. All but 1 LM patient exhibited either papilledema, erythema migrans, or cranial neuropathy. These three findings were absent in the VM group. On CSF analysis, LM patients had fewer white blood cells (mean, 80/mm3 versus 301/mm3) and a significantly greater percentage of mononuclear cells than the VM patients.

CONCLUSIONS

In this study, in a Lyme-endemic area, LM was about as common as VM in older children who were hospitalized with aseptic meningitis. Attention to pertinent epidemiologic and historical data, along with physical and CSF findings, allows early differentiation of LM from VM.

Laboratory diagnosis of common viral infections of the central nervous system by using a single multiplex PCR screening assay

A multiplex PCR assay that detects the four commonest causes of viral meningitis and encephalitis in the United Kingdom (herpes simplex virus [HSV] type 1 [HSV-1], HSV type 2 [HSV-2], varicella-zoster virus [VZV], and enteroviruses) was developed, and its sensitivity was compared with those of similar assays described previously for this application. Compared to the previous assays, this single multiplex PCR assay had higher molecular sensitivities for the detection for each of the viruses and improved utility for routine use in a diagnostic laboratory. The assay was used to test a series of 1,683 consecutive cerebrospinal fluid (CSF) samples between June 1997 and March 1998 inclusively. Viral nucleic acid was detected in 138 (8.2%) of the CSF samples, including enteroviruses in 51 samples, HSV-2 in 33 samples, VZV in 28 samples, and HSV-1 in 25 samples. Compared to the accepted relative incidence of viral etiologies, aseptic meningitis due to HSV-2 infection was high, and in adult female patients with symptoms of aseptic meningitis, HSV-2 was the virus most commonly detected in the CSF.

[PCR SSCP study of an echovirus 30 meningitis outbreak]

Between April and October 1997, 21 children of 4 days to 13 years old were admitted to the Pedatric Unit of Aulnay Sous Bois's Hospital for viral meningitidis. The number of white blood cells in the cerebrospinal fluid (CSF) was between 1 and 612 cells/mm3, with, on an average, 56% of segmented cells, 34% lymphocytes and 34% monocytes. Proteins and glucose of CSF were standard. One CSF was normal. Viral meningitidis was confirmed by viral culture of CSF onto MRC5. Enterovirus were identified by direct immunofluorescence (Monoclonal Mouse Anti-Enterovirus, Dako). Serotyping (Enterovirus antisera, Eurobio, Trousses 4) identified an echovirus 30 in all cases. A highly conserved 154 bp sequence at the 5'non-coding region was studied by reverse transcription-polymerase chain reaction (RT-PCR) followed by single-strand conformation polymorphism (SSCP) (GenPhor, Pharmacia) analysis. Two dominant SSCP patterns were observed: the first contained 4/21 strains and the other 10/21 strains. The SSCP patterns of the 7 other strains were different. These results show that 2 echovirus 30 dominant clones were responsible of viral meningitidis admitted to the Pediatric Unit of Aulnay Sous Bois's hospital, between april and october 1997. The PCR-SSCP of the 5'non-coding region of echovirus 30 is a convenient, simple, reproducible epidemiologic method and it's easily applicable in a general hospital.

[Long central apnea as the chief symptom of aseptic meningoencephalitis in a 6-week-old infant]

Viral infections can cause apnoea, bradycardia, and desaturation events in preterm and new born infants. These symptoms do not always occur in older infants. A link between virus infection, apnoea, apparent life threatening events (ALTE) and sudden infant death (SID) is speculated. We report a 6-week-old infant with long central apnoea as the first and main symptom of meningoencephalitis caused by enterovirus.