Acute community-acquired bacterial meningitis in adults: an evidence-based review

Community-acquired bacterial meningitis is still a significant cause of morbidity and mortality. Clinicians should know how to quickly diagnose it, perform a lumbar puncture, order the necessary tests, and start appropriate empiric therapy promptly.     

Acute bacterial meningitis in adults: a hospital-based epidemiological study

Bacterial meningitis, a world-wide disease, has to be reviewed periodically because the specific micro-organisms responsible for the infection vary with time, geography and patient age. To determine its incidence and clinical features in Taiwan, we reviewed the microbiological records for cerebrospinal fluid (CSF) and blood cultures, and the medical records of patients with bacterial meningitis admitted between 1981 and mid-1998. Bacterial micro-organisms were demonstrated in the CSF and/or blood in 395 patients with 418 episodes of bacterial meningitis. Streptococcus species were the most common causative micro-organism group, at 23. 21% of all episodes. Its prevalence rate significantly decreased from the first 7 years of study (41.9%) to the last 10.5 years (19. 2%). However, Klebsiella meningitis and Staphylococcal meningitis were more frequently noted after 1987. More than 70% of patients had at least one underlying disease or condition. Poor prognostic factors indicated by univariable analysis were: age >60 years; diabetes mellitus; severe neurological deficits on the first day of treatment; infection with Gram-negative bacilli; CSF WBC count >5000x10(6)/l; malignancy; seizure; and bacteraemia. The overall mortality rate was 29.4%, 29.7% in the first 7 years of study and 29. 4% in the last 10.5 years. The use of new antibiotics has not reduced the mortality rate in our patients with bacterial meningitis.     

Acute bacterial meningitis

Despite advances in medical care including antibiotics and vaccines, meningitis still has a high morbidity and mortality rate, especially in certain high-risk patients. Early diagnosis with the administration of appropriate antibiotics remains the key element of management. This article highlights methods of diagnosis, differential diagnoses, treatment options, and complications of treating bacterial meningitis.     

Relapsing bacterial meningitis in adults

Relapsing bacterial meningitis is a rare condition, diagnosedin eight patients between 1981 and 1993 at our institution.These accounted for 3.4% of 234 adult patients with blood and/orcerebrospinal fluid culture-proven bacterial meningitis. A reviewof the English-language literature from 1966 to the presentrevealed only five further adult cases of relapsing bacterialmeningitis with in-depth case histories. Of these 13 total patients,nine were female and four male, aged 17–61 years. Tenwere neurosurgical patients. Gram-negative bacilli, especiallyKlebsiella species, were the commonest micro-organisms identifiedfor both the initial episode and the relapse of infection. Threepatients died in the course of relapse. Four or more weeks ofantibiotic therapy may be needed to treat post-surgical patientswith Gram-negative bacillary meningitis. Even a normal cerebrospinalfluid study at the end of treatment of bacterial meningitisis not a guarantee of freedom from relapse.     

Hyponatraemia in adults with community-acquired bacterial meningitis

BACKGROUND: Hyponatraemia in adults with bacterial meningitis has been described as a common complication, but its true prevalence and clinical importance are unknown. AIM: To investigate the prevalence, clinical characteristics and consequences of hyponatraemia in bacterial meningitis in adults. DESIGN: Nationwide observational cohort study. METHODS: We prospectively assessed the prevalence and clinical characteristics of hyponatraemia among 696 adults with community-acquired bacterial meningitis. Symptoms and signs on admission, blood and CSF test results, radiological examinations and complications during admission were recorded. RESULTS: Sodium levels were determined at admission in 685/696 episodes of bacterial meningitis (98%). Hyponatraemia (<135 mmol/l) was seen in 208/685 (30%) and was classified as severe (<130 mmol/l) in 38 (6%). Hyponatraemia developed during admission in an additional 53 episodes. Hyponatraemia was not associated with an increase in symptoms, with complications or with unfavourable outcome. Treatment for hyponatraemia was initiated in 16% of episodes, but did not influence its duration. DISCUSSION: Hyponatraemia appears both common and benign in adults with bacterial meningitis. In cases of severe hyponatraemia, we suggest the use of fluid maintenance therapy.     

Differential diagnosis between viral and bacterial meningitis in children.

OBJECTIVE: The differential diagnosis between viral meningitis and bacterial meningitis is often very difficult. The results of peripheral blood and spinal fluid analysis are not 100% accurate. We tried to find a useful 'bedside' decision-making tool, based on laboratory results readily available at the emergency department. METHODS: Retrospective study design. Analysis of a consecutive series of all children (age 0-15 years) admitted to the paediatric ward because of a viral or bacterial meningitis, in the period from 1997 to September 2005. RESULTS: Seventy-one children with viral and 21 with bacterial meningitis were included. Bacterial meningitis occurred at much younger ages than viral meningitis. The paediatrician decided to administer antibiotics in 41 of 71 children with viral meningitis and in all children with bacterial meningitis. We developed a 'bacterial meningitis score' based on C-reactive protein in peripheral blood, as well as glucose and protein in cerebrospinal fluid. Using this score, we could distinguish 54 of 71 patients with viral meningitis from the group with bacterial meningitis. When the dispensing of antibiotics was based on this score, only 16 patients with viral meningitis would receive antibiotics. CONCLUSION: We present a bedside bacterial meningitis score. Using this bacterial meningitis score as a decision-making tool, we would be able to avoid antibiotics in a large number of children with viral meningitis. As this gives a 100% success rate, thus guaranteeing that bacterial meningitis patients would receive the proper therapy, our bacterial meningitis score could be an accurate decision-support tool.     

Cerebral haemodynamics in acute bacterial meningitis in adults

BACKGROUND: Vascular complications are an important cause of neurological sequelae among adult survivors of acute bacterial meningitis (ABM). AIM: To examine the haemodynamic changes associated with ABM. METHODS: Serial transcranial colour-coded sonography (TCCS) and magnetic resonance angiography (MRA) were used to examine cerebrovascular changes in adult ABM patients. Outcome at 3 months was categorized using a modified Barthel index. RESULTS: We recruited 24 patients, 12 men and 12 women, aged 21-68 years. Mean cerebral blood flow velocity (V(mean)) increased from day 1 to day 4 in the middle cerebral artery (MCA), anterior cerebral artery (ACA) and posterior cerebral artery (PCA). On day 4, V(mean) values in the MCA, ACA and PCA were all significantly higher than reference values in healthy volunteers. At 3 months follow-up, 16 cases had good outcomes, while the other eight had poor outcomes. Under multiple logistic regression analysis, only Glasgow coma score (GCS) at admission was independently associated with the three-month outcome. DISCUSSION: In these patient, stenosis as demonstrated by TCCS did not wholly coincide with stenosis as demonstrated by MRA, and the presence of intracranial stenosis was not predictive of a poor outcome at 3 months. Further studies are needed to delineate the characteristics and significance of cerebrovascular changes in adult ABM.     

Pharmacokinetics of cefuroxime in infants and children with bacterial meningitis.

A total of 38 patients with bacterial meningitis received either 50 or 75 mg of cefuroxime per kg of body weight given as a 15-min intravenous infusion during the first to third days of therapy. The mean peak plasma concentrations of cefuroxime after doses of 50 and 75 mg/kg were 105 and 152 micrograms/ml, respectively. In five patients, pharmacokinetic values were determined after multiple doses of 50 mg of cefuroxime per kg every 6 h. The mean peak plasma concentrations were 120 micrograms/ml after the first dose and 130 micrograms/ml after the last dose. The concentrations at 6 h were 3.25 and 11.0 micrograms/ml after the first and last doses, respectively. The elimination half-life was approximately 1.5 h, and the apparent volume of distribution was 650 ml/kg. The plasma clearance rate was 195 to 198 ml/min per 1.73 m2. Penetration into the cerebrospinal fluid, expressed as the ratio of the cerebrospinal fluid to serum areas under the curve times 100, was 6.4% in patients given 50 mg of cefuroxime per kg and 10% in those who received 75 mg/kg. The cerebrospinal bactericidal activity in 27 patients was less than or equal to 1:8; only 2 patients had bactericidal activity of less than or equal to 1:2.     

Ceftriaxone monotherapy for bacterial meningitis in children

A total of 33 patients with bacterial meningitis were treated with single daily doses of ceftriaxone (CTR 100 mg/kg/day i.v.) for a median duration of 13 days. Pathogens isolated by culture and/or determined by latex agglutination were 15 Haemophilus influenzae b, 7 Neisseria meningitidis, 2 Streptococcus pneumoniae, 1 group B streptococcus, 2 Streptococcus viridans and 2 Staphylococcus epidermidis. In 4 cases a diagnosis of purulent meningitis could only be made by means of the inflammatory liquor parameters. All cerebrospinal fluid (CSF) drug levels even at the end of the dosing interval were at least 10-fold higher than the MICs of the respective bacterial isolates. The average penetration of CTR into the CSF was 6.6%. Within 12-46 h after the first dose, control spinal taps were performed. Cultures were sterile in all cases. Side effects encountered were diarrhea, exanthema, neutropenia and transient elevation of glutamic oxaloacetic transaminase, but none caused a change of therapy. One patient developed a biliary concrement. No patient died; 5 patients had prolonged fever (greater than 5 days), and 2 were left with persistent hearing deficiencies. CTR can be recommended as a safe and effective antibiotic agent for once daily treatment of bacterial meningitis in children.     

New issues in bacterial meningitis in adults. Antibiotic resistance has complicated treatment

The epidemiologic factors of bacterial meningitis, a serious disease that must be addressed with great urgency, have evolved dramatically in the last 25 years. Among both adults and children, multidrug-resistant Streptococcus pneumoniae has emerged as a clinical challenge and has greatly complicated the empirical management of this disease. In this article, the author focuses on new issues involving the epidemiologic factors, diagnosis, treatment, and prevention of bacterial meningitis in adults.     

Cerebral malaria versus bacterial meningitis in children with impaired consciousness.

Cerebral malaria (CM) and acute bacterial meningitis (ABM) are the two common causes of impaired consciousness in children presenting to hospital in sub-Sahara Africa. Since the clinical features of the two diseases may be very similar, treatment is often guided by the initial laboratory findings. However, no detailed studies have examined the extent to which the laboratory findings in these two diseases may overlap. We reviewed data from 555 children with impaired consciousness admitted to Kilifi District Hospital, Kenya. Strictly defined groups were established based on the malaria slide, cerebrospinal fluid (CSF) leucocyte count and the results of blood and CSF culture and CSF bacterial antigen testing. Our data suggests significant overlap in the initial CSF findings between CM and ABM. The absolute minimum proportions of children with impaired consciousness and malaria parasitaemia who also had definite bacterial meningitis were 4% of all children and 14% of children under 1 year of age. The estimated maximum proportion of all children with impaired consciousness and malaria parasitaemia in whom the diagnosis was dual or unclear was at least 13%. The finding of malaria parasites in the blood of an unconscious child in sub-Saharan Africa is not sufficient to establish a diagnosis of cerebral malaria, and acute bacterial meningitis must be actively excluded in all cases.     

Cefuroxime treatment of bacterial meningitis in infants and children

Recently, ampicillin- and chloramphenicol-resistant strains of Haemophilus influenzae type b and multiply-resistant Salmonella strains have appeared in some areas of the world. Therefore, alternative drug therapy for infections caused by these organisms is being sought. We used cefuroxime to successfully treat five children with H. influenzae type b meningitis and two children with Salmonella meningitis. Four H. influenzae type b isolates and one Salmonella isolate were resistant to ampicillin, chloramphenicol, and cotrimoxazole. Each of the patients received 200 to 250 mg of cefuroxime per kg per day in four divided doses for 14 to 21 days. The concentrations of cefuroxime in cerebrospinal fluid at 2 h after intravenous 50-mg/kg doses were 6.4 +/- 1.7 (mean +/- standard deviation) and 3.6 +/- 2.2 micrograms/ml on days 2 and 14 of treatment, respectively. The level of drug in cerebrospinal fluid was 1.34 +/- 1.3 micrograms/ml in children without meningitis. The mean cefuroxime concentration in subdural fluid samples from each of three patients was 12.6, 15, and 25.2 micrograms/ml. Cefuroxime is recommended as an alternative drug for the treatment of H. influenzae type b meningitis, but additional information is necessary before cefuroxime can be recommended for therapy of Salmonella meningitis.     

Acute bacterial rhinosinusitis in adults: part I. Evaluation

Acute rhinosinusitis is one of the most common conditions that physicians treat in ambulatory practice. Although often caused by viruses, it sometimes is caused by bacteria, a condition that is called acute bacterial rhinosinusitis. The signs and symptoms of acute bacterial rhinosinusitis and prolonged viral upper respiratory infection are similar, which makes accurate clinical diagnosis difficult. Because two thirds of patients with acute bacterial rhinosinusitis improve without antibiotic treatment and most patients with viral upper respiratory infection improve within seven d antibiotic therapy should be reserved for use in patients who have had symptoms for more than seven days and meet clinical criteria. Four signs and symptoms are the most helpful in predicting acute bacterial rhinosinusitis: purulent nasal discharge, maxillary tooth or facial pain (especially unilateral), unilateral maxillary sinus tenderness, and worsening symptoms after initial improvement. Sinus radiography and ultrasonography are not recommended in the diagnosis of uncomplicated acute bacterial rhinosinusitis, although computed tomography has a role in the care of patients with recurrent or chronic symptoms.     

Acute bacterial rhinosinusitis in adults: part II. Treatment

Although most cases of acute rhinosinusitis are caused by viruses, acute bacterial rhinosinusitis is a fairly common complication. Even though most patients with acute rhinosinusitis recover promptly without it, antibiotic therapy should be considered in patients with prolonged or more severe symptoms. To avoid the emergence and spread of antibiotic-resistant bacteria, narrow-spectrum antibiotics such as amoxicillin should be used for 10 to 14 days. In patients with mild disease who have beta-lactam allergy, trimethoprim/sulfamethoxazole or doxycycline are options. Second-line antibiotics should be considered if the patient has moderate disease, recent antibiotic use (past six weeks), or no response to treatment within 72 hours. Amoxicillin-clavulanate potassium and fluoroquinolones have the best coverage for Haemophilus influenzae and Streptococcus pneumoniae. In patients with beta-lactam hypersensitivity who have moderate disease, a fluoroquinolone should be prescribed. The evidence supporting the use of ancillary treatments is limited. Decongestants often are recommended, and there is some evidence to support their use, although topical decongestants should not be used for more than three days to avoid rebound congestion. Topical ipratropium and the sedating antihistamines have anticholinergic effects that maybe beneficial, but there are no clinical studies supporting this possibility. Nasal irrigation with hypertonic and normal saline has been beneficial in chronic sinusitis and has no serious adverse effects. Nasal corticosteroids also may be beneficial in treating chronic sinusitis. Mist, zinc salt lozenges, echinacea extract, and vitamin C have no proven benefit in the treatment of acute bacterial rhinosinusitis.     

Diagnosis of bacterial meningitis in previously treated children

We reviewed the charts of 115 children with the clinical diagnosis of bacterial meningitis admitted to our hospital over a period of eight years. Of these, 47 patients had received antimicrobial agents before hospitalization and eight (17%) of them had negative cerebrospinal fluid (CSF) cultures. These eight children, however, had CSF features suggestive of bacterial meningitis. We conclude that prior antimicrobial therapy does not alter the chemical properties of CSF, the response to pharmacologic agents, or the ultimate outcome, even though previously treated children may have lower rates of positive CSF and blood cultures.     

Arterial cerebrovascular complications in 94 adults with acute bacterial meningitis

Introduction  

Intracranial vascular complications are an important complication of acute bacterial meningitis. Ischemic stroke in meningitis is reported as a result of vasculitis, vasospasm, endocarditis or intraarterial thrombosis. The aim of the study was to identify the value of measuring cerebral blood flow velocity (CBFv) on transracranial doppler (TCD) in the identification of patients at risk for meningitis-associated stroke.