For an overview of meningitis, see Overview of Meningitis. For acute bacterial meningitis in older children and adults, see Acute Bacterial Meningitis, and in children < 3 months, see Neonatal Bacterial Meningitis. For viral meningitis, including in infants and children, see Viral Meningitis.
Etiology of Bacterial Meningitis in Infants
The etiology and incidence of bacterial meningitis are closely related to age and whether the infants have received routine immunization with the Haemophilus influenzae type b conjugate vaccine and the Streptococcus pneumoniae conjugate vaccine (1).
In infants who have not received routine immunizations, common causes of bacterial meningitis include (2)
S. pneumoniae (many serotypes; particularly in infants with no record of S. pneumoniae conjugate vaccination)
Neisseria meningitidis (especially serogroup B, but occasionally groups A, C, Y, or W135)
H. influenzae type b (particularly in infants with no record of H. influenzae type b conjugate vaccination)
Other etiologies of bacterial meningitis in infants and children > 3 months of age have been reported but are very rare. Listeria monocytogenes, Streptococcus agalactiae, and Escherichia coli cause disease in infants < 3 months of age; they rarely are the etiology in extremely premature infants who have survived to become > 3 months of age. Staphylococcus aureus meningitis may occur in infants who have had trauma or neurologic surgery.
Etiology references
1. Committee on Infectious Diseases, American Academy of Pediatrics: Red Book: 2021–2024 Report of the Committee on Infectious Diseases, ed. 32, edited by Kimberlin DW, Barnett ED, Lynfield R, and Sawyer MH. Itasca, American Academy of Pediatrics, 2021.
2. Weinberg GA, Stone RT: Bacterial infections of the nervous system. In Swaiman's Pediatric Neurology: Principles and Practice, 6th ed., edited by Swaiman KF, Ashwal S, Ferriero DM, et al. Philadelphia, Elsevier, 2018, pp 883–894.
Symptoms and Signs of Bacterial Meningitis in Infants
The younger the patient, the less specific are the symptoms and signs of meningitis.
The initial manifestations of bacterial meningitis may be an acute febrile illness with respiratory or gastrointestinal symptoms followed only later by signs of serious illness. Approximately 33 to 50% of neonates have a bulging anterior fontanelle, but only rarely do they have nuchal rigidity or other classic meningeal signs (eg, Kernig sign or Brudzinski sign) typically present in older children. In children < 12 months, the absence of nuchal rigidity must not be used to exclude meningitis.
Pearls & Pitfalls
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As bacterial meningitis progresses, children develop central nervous system (CNS) manifestations, sometimes very rapidly. The degree of CNS derangement ranges from irritability to coma. As many as 15% of children who have bacterial meningitis are comatose or semicomatose at the time of hospitalization. Seizures sometimes occur with bacterial meningitis but in only about 20% of children—typically those who are already toxic, obtunded, or comatose. Infants who are alert and appear normal after a brief, non-focal seizure with fever are unlikely to have bacterial meningitis (see also Febrile Seizures).
Papilledema is very uncommon in children of any age with bacterial meningitis. When papilledema is present, other causes of papilledema should be sought; bacterial meningitis progresses so quickly that there is usually insufficient time for papilledema to develop.
Diagnosis of Bacterial Meningitis in Infants
Cerebrospinal fluid (CSF) analysis and Gram stain
In general, lumbar puncture should be performed whenever the diagnosis of meningitis is known or suspected in an infant.
However, lumbar puncture may be delayed for the following reasons:
Clinically important cardiorespiratory compromise (most often in young infants)
Signs of significantly increased intracranial pressure, including retinal changes; altered pupillary responses; hypertension, bradycardia, and respiratory depression (Cushing triad); and focal neurologic signs
Suspected intracranial injury, including presence of visible injuries, particularly to the head, or history suggestive of nonaccidental injury
Infection at the site of lumbar puncture
Suspicion or history of bleeding disorders (eg, hemophilia, severe thrombocytopenia)
In these circumstances, blood cultures should be done and antibiotics should be given empirically without doing the lumbar puncture. In cases of suspected increased intracranial pressure, arrangements should be made for a neuroimaging study (eg, cranial CT with and without contrast enhancement, cranial ultrasonography) during or immediately after antibiotics administration. If the results of the imaging study suggest it is safe, lumbar puncture may be done. However, it is not necessary to routinely do CT before lumbar puncture in young children with suspected meningitis; herniation of the brain is rare in young children with bacterial meningitis, even though all patients with meningitis have some degree of increased intracranial pressure.
CSF is sent for analysis, typically cell count, protein, glucose, Gram stain, culture, and, in selected infants, polymerase chain reaction (PCR) tests for enteroviruses (eg, in infants with meningitis during the late summer and autumn months in the United States), herpes simplex virus, or parechovirus. A PCR panel may be useful where available. Simultaneously, a blood sample should be drawn and sent to have the CSF:blood glucose ratio determined.
Typical CSF findings in bacterial meningitis include
High white blood cell (WBC) count (> 500/mcL [0.5 × 109/L], often to as high as 10,000 WBC/mcL [10 × 109/L], with a predominance of polymorphonuclear leukocytes [> 80%])
Elevated protein (> 100 mg/dL [1 gm/L])
Low glucose (< 40 mg/dL [2.2 mmol/L], often < 10 mg/dL [0.56 mmol/L], and CSF:blood glucose ratio typically < 0.33)
Gram stain often shows organisms in the CSF in bacterial meningitis. Although findings may vary somewhat, infants who have bacterial meningitis very rarely have completely normal CSF at examination.
Infants also should have an evaluation for systemic illness and for other sources of infection, including 2 sets of blood cultures (if possible; minimum 1 set of aerobic and anaerobic culture bottles), serum electrolytes, complete blood count and differential, and a urinalysis and urine culture.
Differential diagnosis
Symptoms and signs of bacterial meningitis may also be caused by other CNS infections, including viral meningitis (typically enteroviral or, in young infants, parechoviral), neonatal HSV infection (almost exclusively in the infant < 1 month of age), pediatric HSV encephalitis, and brain abscess.
Other causes of CNS infections that affect older children and adults (eg, Lyme neuroborreliosis; fungal meningitis; tuberculous meningitis; Bartonella
In these other causes of meningitis, CSF findings most often include < 500 WBC/mcL (0.5 × 109/L) with < 50% polymorphonuclear leukocytes, protein < 100 mg/dL (1 g/L), normal glucose, and a negative Gram stain for organisms.
Treatment of Bacterial Meningitis in Infants
Antimicrobial therapy
As soon as bacterial meningitis is diagnosed (actually or presumptively), IV access should be secured and appropriate antimicrobials (and possibly corticosteroids) should be given.
Empiric antimicrobial therapy for infants > 3 months is directed at the common pathogens: pneumococci, meningococci, and H. influenzae type b.
A typical antibiotic regimen includes
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Ceftriaxone is extremely effective against the organisms that usually cause bacterial meningitis in infants > 3 months. Vancomycin is given because some pneumococcal strains in certain areas are not susceptible to advanced-generation cephalosporins. In areas (and institutions) where most pneumococci are susceptible to penicillin, vancomycin may not be necessary, particularly if no gram-positive cocci are seen on the CSF Gram stain; decision to withhold vancomycin should typically be made in consultation with an infectious diseases specialist.
Once the infecting organism is identified, more specifically targeted antibiotics are used; for example, vancomycin may no longer be required.
Organism-specific antimicrobial therapy
After immediate empiric antimicrobials have been started, results of CSF and/or blood cultures are used to select a more specifically targeted antibiotic while waiting for microbial identification and susceptibility test results. (See table Specific Therapy for Bacterial Meningitis in Infants Over 3 Months of Age Once Identification and Susceptibility Results Are Known.)
If S. pneumoniae is suspectedVancomycin is stopped if the isolate is susceptible to penicillin or ceftriaxone; if the isolate is notvancomycin, some experts advise that either dexamethasone should not be given or, if given, that rifampin be added concurrently.
Disease caused by N. meningitidisampicillinrifampin
If H. influenzae type b is suspected or proved,ampicillinrifampin is not necessary if ceftriaxone is used to complete therapy).
Specific antimicrobial therapy for other rare infections (eg, S. agalactiae, E. coli, L. monocytogenes, S. aureus) should be selected in consultation with an infectious diseases specialist.
Specific Therapy for Bacterial Meningitis in Infants Over 3 Months of Age Once Identification and Susceptibility Results Are Known
Pathogen | Therapy |
|---|---|
Streptococcus pneumoniae | ceftriaxone or cefotaxime also acceptable Ceftriaxone or cefotaxime for 10–14 days Ceftriaxone or cefotaxime, plus |
Neisseria meningitidis | Alternatives: |
Haemophilus influenzae type b | Alternative: |
MIC = minimum inhibitory concentration. | |
Corticosteroids for bacterial meningitis
H. influenzae type b (1). The effectiveness of dexamethasone in meningitis caused by other organisms remains unproved, although some studies of adults in high-resource areas with meningitis caused by S. pneumoniae report improved neurologic outcomes and reduced mortality (1, 2). Dexamethasone does not appear to benefit children or adults with bacterial meningitis who live in low-resource areas nor does it seem to benefit neonates with meningitis.
H. influenzae type b. Dexamethasone is continued every 6 hours for 4 days in confirmed H. influenzae type b meningitis. Some experts also recommend using this same dexamethasone regimen in children with pneumococcal meningitis who are > 6 weeks of age.
H. influenzae type b and pneumococcal conjugate vaccines, bacterial meningitis caused by these organisms is rare. For these reasons, along with the conflicting evidence regarding the benefits of dexamethasone therapy, many pediatric infectious disease experts no longer routinely give corticosteroids to infants with meningitis.
Treatment references
1. Brouwer MC, McIntyre P, Prasad K, van de Beek D: Corticosteroids for acute bacterial meningitis. Cochrane Database Syst Rev 2015(9):CD004405, 2015. doi: 10.1002/14651858.CD004405.pub5
2. Hasbun R: Progress and Challenges in Bacterial Meningitis: A Review [published correction appears in JAMA. 2023 Feb 14;329(6):515]. JAMA 328(21):2147-2154, 2022. doi: 10.1001/jama.2022.20521
Prognosis for Bacterial Meningitis in Infants
Among older infants and children, the mortality rate with bacterial meningitis is approximately 5 to 15% (1, 2), and neurologic morbidity (eg, sensorineural hearing loss, intellectual disability, spasticity and paresis, seizure disorder) occurs in 15 to 25% (3). Sensorineural deafness is most common after pneumococcal meningitis.
In older infants and children, mortality rates vary from 3 to 5% when the cause is H. influenzae type b, 5 to 10% when the cause is N. meningitidis, and 10 to 20% when the cause is S. pneumoniae (4).
Prognosis references
1. Mongelluzzo J, Mohamad Z, Ten Have TR, Shah SS: Corticosteroids and mortality in children with bacterial meningitis. JAMA 299(17):2048-2055, 2008. doi: 10.1001/jama.299.17.2048
2. Thigpen MC, Whitney CG, Messonnier NE, et al: Bacterial meningitis in the United States, 1998-2007. N Engl J Med 364(21):2016-2025, 2011. doi: 10.1056/NEJMoa1005384
3. Baraff LJ, Lee SI, Schriger DL: Outcomes of bacterial meningitis in children: a meta-analysis. Pediatr Infect Dis J 12(5):389-394, 1993. doi: 10.1097/00006454-199305000-00008
4. Hasbun R: Progress and Challenges in Bacterial Meningitis: A Review [published correction appears in JAMA. 2023 Feb 14;329(6):515]. JAMA 328(21):2147-2154, 2022. doi: 10.1001/jama.2022.20521
Prevention of Bacterial Meningitis in Infants
Prevention of bacterial meningitis involves vaccination and sometimes chemoprophylaxis.
Vaccination
A pneumococcal conjugate vaccine is recommended for all children beginning at 2 months of age (see ). For further information, see Advisory Committee on Immunization Practices (ACIP) pneumococcal vaccine recommendations and the Centers for Disease Control and Prevention's child and adolescent immunization schedule by age.
Routine vaccination with an H. influenzae type b conjugate vaccine also is highly effective and begins at age 2 months. For further information, see ACIP Haemophilus influenzae vaccine recommendations.
The ACIP recommends that infants > 6 weeks of age who are at high risk of meningococcal disease receive a meningococcal conjugate vaccine. High-risk infants include those who
Have HIV infection
Have functional or anatomic asplenia (including patients with sickle cell disease)
Have persistent complement component pathway deficiencies
Travel to or reside in a high-risk area (eg, sub-Saharan Africa or Saudi Arabia)
Are exposed to an outbreak attributable to a vaccine serogroup
For infants not at high risk, routine meningococcal conjugate vaccination is recommended at age 11 or 12 years with a booster dose at age 16 years.
Two serogroup B meningococcal vaccines have been approved by the ACIP for use in children ≥ 10 years of age who are at high risk of meningococcal group B disease (same categories as above); routine meningococcal B vaccination is not yet currently given. For further information, see ACIP meningococcal vaccine recommendations.
Chemoprophylaxis for meningitis
N. meningitidis meningitis: All close contacts
H. influenzae meningitis: Selected close contacts
Contacts of children who have meningitis caused by other bacteria do not require chemoprophylaxis.
For meningococcal meningitis, close contacts have a risk of infection that may be 25 to 500 times higher than that of the general population. Close contacts are defined as (1)
Household members, especially children < 2 years of age
Child care center contacts exposed in the 7 days before symptom onset
Anyone directly exposed to the patient’s oral secretions (eg, through kissing, sharing toothbrushes or utensils, mouth-to-mouth resuscitation, endotracheal intubation, endotracheal tube management) in the 7 days before symptom onset
Not every health care professional who has cared for an infant with meningitis is considered a close contact. Health care personnel should receive chemoprophylaxis only if they were managing the patient's airway or were directly exposed to the patient's respiratory secretions.
Chemoprophylaxis should be given as soon as possible (ideally within 24 hours of identification of the index patient); chemoprophylaxis given > 2 weeks after exposure is likely of little to no value. Rifampin, ceftriaxone, and ciprofloxacin are appropriate antimicrobials depending on the age of the contact. For young children, oral rifampin
For H. influenzae type b meningitis, the risk of infection in contacts is lower than with meningococcal disease but can be substantial in young, unvaccinated infant or toddler contacts residing in the household of an index patient. Also, household contacts may be asymptomatic carriers of H. influenzae type b.
Close contacts are defined more explicitly than for meningococcal prophylaxis because caretakers who spend time in the household but do not live there may nevertheless have become colonized with H. influenzae type b. Thus, for this organism, household contacts are defined as the following (1):
People who live with the index patient
People who have spent ≥ 4 hours with the index patient for ≥ 5 of the 7 days preceding the index patient's hospital admission
Chemoprophylaxis is then recommended for each member of the household, as just defined, if that household also has
At least 1 contact < 4 years who is incompletely immunized or unimmunized
A child < 12 months who has not completed the primary Hib conjugate immunization series
An immunocompromised child (regardless of previous immunization status)
Complete immunization against H. influenzae type b is defined as having had at least 1 dose of Hib conjugate vaccine at age ≥ 15 months, or 2 doses between 12 months and 14 months, or the 2- or 3-dose primary series for children < 12 months with a booster dose at ≥ 12 months.
In addition, if a preschool or child care center has had ≥ 2 cases of invasive Hib disease within 60 days among its attendees, many experts recommend chemoprophylaxis for all attendees and staff to eliminate asymptomatic nasal carriage regardless of immunization status.
Close contacts most at risk of secondary infection are children < 4 years who are incompletely immunized against H. influenzaeRifampin is given 1 time a day for 4 days.
Prevention reference
1. Committee on Infectious Diseases, American Academy of Pediatrics: Red Book: 2021–2024 Report of the Committee on Infectious Diseases, ed. 32, edited by Kimberlin DW, Barnett ED, Lynfield R, and Sawyer MH. Itasca, American Academy of Pediatrics, 2021.
Key Points
Infants with bacterial meningitis may first present with nonspecific symptoms and signs (eg, of upper respiratory or gastrointestinal illness) but then decompensate rapidly.
The most common bacterial causes of meningitis are Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b.
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Provide antimicrobial chemoprophylaxis to select contacts of patients with N. meningitidis meningitis or H. influenzae meningitis.
More Information
The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
Advisory Committee for Immunization Practices (ACIP): Pneumococcal vaccine recommendations
Centers for Disease Control and Prevention (CDC): Child and Adolescent Immunization Schedule by Age
American Academy of Pediatrics: Red Book: 2021–2024 Report of the Committee on Infectious Diseases
