Bacterial meningitis

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Bacterial meningitis may prove fatal within hours. Patients with suspected acute bacterial meningitis should be rapidly admitted to the hospital and assessed to determine whether a lumbar puncture (LP) is clinically safe.

Antimicrobials should be given promptly. If the LP is delayed because a computed tomography scan is needed, antibiotic treatment should be started before the scan and after blood samples have been obtained for culture. Delaying antibiotics is strongly associated with poor outcome and death.[38][66][67] When the specific organism is identified and results of susceptibilities are known, treatment can be modified accordingly.

The following recommendations are for community-acquired meningitis. Recommendations for the management of healthcare-associated meningitis are beyond the scope of this topic, and guidelines are available elsewhere.[65] Meningococcal disease is covered as a separate topic.

Suspected bacterial meningitis

Empiric parenteral broad-spectrum antibacterial therapy should be given as soon as possible for suspected bacterial meningitis (preferably after an LP has been performed).[9][65][68] In some countries, administration of antibiotics (e.g., intramuscular penicillin G, cefotaxime, or ceftriaxone) in primary care is recommended if transfer to the hospital is likely to be delayed.[69] However, the evidence for this approach is equivocal.[70]

The choice of empiric antibiotic depends on the patient's age and the conditions that may have predisposed the patient to meningitis.[65] The regimen chosen must be broad enough to cover the potential organisms for the age group affected. For initial therapy, the assumption should be that antimicrobial resistance is likely.[65] Most empiric therapy regimens include a third- or fourth-generation cephalosporin plus vancomycin. Ampicillin is added in situations where Listeria monocytogenes may be a pathogen (e.g., older people, immunocompromised, and newborns).[1]

A proposed treatment strategy based on age and specific predisposing conditions follows.[38][68]

Age ≤1 month immunocompetent: cefotaxime or an aminoglycoside (e.g., gentamicin) PLUS ampicillin
Age >1 month and <50 years immunocompetent: cefotaxime or ceftriaxone PLUS vancomycin
Age ≥50 years or immunocompromised: ampicillin PLUS cefotaxime or ceftriaxone PLUS vancomycin.

If a cephalosporin cannot be administered (e.g., patients with an allergy), alternative antibiotics include a carbapenem (e.g., meropenem) or chloramphenicol.[1] Trimethoprim/sulfamethoxazole is an alternative to ampicillin (excluding newborns).

Adjunctive corticosteroid

Ideally, adjuvant dexamethasone should be given with or shortly before the first dose of parenteral antibiotics in all previously well and non-immunosuppressed adults and children.[68] However, it may be given within 4 hours of the first dose of antibiotics.[38]

Evidence of potential benefit has been demonstrated in cases of bacterial meningitis associated with Haemophilus influenzae or Streptococcus pneumoniae. There is little evidence to support the use of dexamethasone in cases caused by other bacteria (e.g., in cases of meningococcal meningitis); dexamethasone should be stopped early when H influenzae and S pneumoniae have been excluded as causative organisms.[38]

Adults and children

Adjunctive therapy with dexamethasone, given before or within 4 hours of the first dose of antibiotics and continued for 4 days, has been shown to improve outcomes in adults.[71][72][73][74]

One Cochrane review found insufficient evidence to demonstrate that adding corticosteroids to antibacterial therapy reduced overall mortality in a mixed population of adults and children with acute bacterial meningitis.[73] Significant reduction in rates of hearing loss and neurologic sequelae were, however, reported in adults and children; short-term neurologic sequelae were reduced in children, but not in adults.[38][73] [ ] [ ] These results were replicated in a subsequent meta-analysis of randomized controlled trials related to the treatment of bacterial meningitis in children with dexamethasone.[75]

Subgroup analyses of the Cochrane review suggested that corticosteroids may reduce: mortality in S pneumoniae meningitis (but not in H influenzae type b [Hib] or Neisseria meningitidis meningitis); severe hearing loss in children with Hib meningitis (but not in children with meningitis due to non-Haemophilus species).[73]

One meta-analysis that included a heterogeneous group of critically ill adult patients reported potentially improved survival among a subgroup of patients with bacterial meningitis who received corticosteroids compared with those who did not (mortality 28% vs. 32%; P=0.04).[76]

Neonates

There is low-quality evidence to suggest dexamethasone may reduce death and hearing loss in neonates with bacterial meningitis.[77]

Corticosteroids are, however, not currently recommended in neonates.[38]

Confirmed bacterial meningitis

After the diagnosis has been confirmed (generally within 12-48 hours of admission to the hospital), the patient's antibacterial therapy can be modified according to the causative organism and its susceptibilities.[9][65]

Typically, the duration of antibacterial treatment depends on the clinical response and the cerebrospinal fluid (CSF) microbiologic response after treatment has started. Supportive therapy, such as fluid replacement, should be continued.

S pneumoniae (duration of therapy 10-14 days)

Penicillin-susceptible (minimum inhibitory concentration [MIC] <0.1 microgram/mL): ampicillin or penicillin G
Penicillin-intermediate (MIC=0.1 to 1.0 microgram/mL): cefotaxime or ceftriaxone
Penicillin-resistant (MIC ≥2.0 micrograms/mL) or cephalosporin-resistant (MIC ≥1.0 microgram/mL): vancomycin AND cefotaxime or ceftriaxone.

H influenzae (duration of therapy 7-10 days)

Beta-lactamase-negative: ampicillin
Beta-lactamase-positive: cefotaxime or ceftriaxone.

Streptococcus agalactiae (group B streptococci) (duration of therapy 14-21 days)

Gentamicin AND ampicillin or penicillin G.

Escherichia coli and other gram-negative Enterobacteriaceae (duration of therapy 21-28 days)

Gentamicin AND cefotaxime or ceftriaxone.

Listeria monocytogenes (duration of therapy 21-28 days)

Gentamicin AND ampicillin or penicillin G.

Staphylococcus aureus (duration of therapy depends on microbiologic response of CSF and underlying illness of the patient)

Methicillin-susceptible: nafcillin or oxacillin
Methicillin-resistant: vancomycin.

Staphylococcus epidermidis (duration of therapy depends on microbiologic response of CSF and underlying illness of the patient)

Vancomycin.

Pseudomonas aeruginosa (duration of therapy 21 days)

Ceftazidime and gentamicin.

Enterococcus species (duration of therapy 21 days)

Ampicillin and gentamicin.

Acinetobacter species (duration of therapy 21 days)

Gentamicin and meropenem.

N meningitides (duration of therapy 7 days)[38]

Penicillin-susceptible (MIC <0.1 microgram/mL): ampicillin or penicillin G
Penicillin-intermediate (MIC=0.1 to 1.0 microgram/mL): cefotaxime or ceftriaxone.

Supportive therapy

The major goal of supportive therapy is to restore and maintain normal respiratory, cardiac, and neurologic function. Meningococcal infections may progress rapidly and clinical deterioration may continue despite prompt administration of antimicrobial therapy.

Initial assessment should follow the principles of pediatric and adult advanced life support, by evaluating the patient's airway, breathing, and circulatory status, and establishing secure, large-caliber intravenous catheters for giving fluids.[78][79]

Patients with symptoms of compensated shock (neurologic status usually remains normal, but the pulse rate may be persistently elevated, the skin mottled, the extremities cool due to increased systemic vascular resistance, the capillary refilling prolonged, and the urinary output decreased) or respiratory distress should receive supplemental oxygen. Those with decompensated shock (signs of compensated shock plus hypotension), hypoxia, severe respiratory distress, altered consciousness, or evidence of elevated intracranial pressure require intubation and mechanical ventilation.

Adequate oxygenation, prevention of hypoglycemia and hyponatremia, anticonvulsant therapy to control and prevent seizures (e.g., lorazepam, diazepam, phenytoin), and measures to decrease intracranial pressure and to prevent fluctuating cerebral blood flow are important in managing patients with bacterial meningitis.[9] Vasopressors should be given to patients with hypotension or poor perfusion who do not respond promptly to fluid resuscitation. If the patient is hypovolemic or in shock (state of reduced end-organ oxygenation caused by an imbalance between tissue oxygen delivery and demand resulting in an oxygen debt), additional intravenous fluids must be given. One systematic review found insufficient evidence to guide practice on whether maintenance or restricted fluid regimens should be used.[80] However, fluids should be given cautiously to patients with evidence of elevated intracranial pressure, myocardial dysfunction, or acute respiratory distress syndrome.

Central venous catheter insertion: animated demonstration

Ultrasound-guided insertion of a non-tunnelled central venous catheter (CVC) into the right internal jugular vein using the Seldinger insertion technique.

Peripheral intravascular catheter: animated demonstration

How to insert a peripheral intravascular catheter into the dorsum of the hand.

Tracheal intubation: animated demonstration

How to insert a tracheal tube in an adult using a laryngoscope.

Bag-valve-mask ventilation: animated demonstration

How to use bag-valve-mask apparatus to deliver ventilatory support to adults. Video demonstrates the two-person technique.

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