Symptoms and signs of bacterial meningitis may also be caused by other CNS infections, including viral meningitis (typically enteroviral), HSV encephalitis (almost exclusively in the infant < 3 mo of age), and brain abscess. Other causes of CNS infections that affect older children and adults (eg, Lyme neuroborreliosis; fungal meningitis; tuberculous meningitis; Bartonella infection; chemical meningitis resulting from use of NSAIDs, trimethoprim/sulfamethoxazole, or IV immune globulin; cancer) rarely occur in children < 12 mo and should be distinguishable based on history, physical examination, and examination of the CSF.

In these other causes of meningitis, CSF findings most often include < 500 WBC/μL with < 50% polymorphonuclear leukocytes, protein < 100 mg/dL, normal glucose, and a negative Gram stain for organisms.

After immediate empiric antimicrobial drugs have been started, results of CSF and/or blood cultures are used to select a more specifically targeted drug while waiting for microbial identification and susceptibility test results.

If S. pneumoniae is suspected (eg, because gram-positive cocci in pairs are seen on a Gram stain of the CSF), the empiric vancomycin should be continued until susceptibility test results are available. Vancomycin is stopped if the isolate is susceptible to penicillin or the 3rd-generation cephalosporins; if the isolate is not susceptible, vancomycin is continued (and some clinicians add rifampin). Because dexamethasone can decrease the CSF penetrance (and thus effectiveness) of vancomycin, some experts advise that either dexamethasone should not be given, or if given, that rifampin be added concurrently.

If H. Influenzae type b is suspected or proven, disease may be treated reliably with either ceftriaxone or cefotaxime; ampicillin may be used only if the isolate is proved susceptible. If ampicillin therapy is used, it is followed by a 4-day course of once-daily rifampin to clear the carrier state and prevent relapse (rifampin is not necessary if a 3rd-generation cephalosporin is used to complete therapy).

Disease caused by N. meningitidis is treated reliably with penicillin G or ampicillin at high doses, or alternatively by a 3rd-generation cephalosporin. If penicillin or ampicillin therapy is used, it is followed by a 2-day course of twice-daily rifampin to clear the carrier state and prevent relapse (rifampin is not necessary if a 3rd-generation cephalosporin is used to complete therapy).

Other etiologies of bacterial meningitis in infants and children > 3 mo of age have been reported but are very rare. Listeria monocytogenes,S. agalactiae, and E. coli cause disease in infants < 3 mo of age; they rarely are found in extremely premature infants who have survived to become > 3 mo of age. S. aureus meningitis may occur in infants who have had trauma or neurologic surgery. Specific antimicrobial therapy for these types of rare infections should be selected in consultation with an infectious disease specialist.

The use of corticosteroids (eg, dexamethasone) as adjunctive therapy in bacterial meningitis has been studied for decades and continues to be controversial. The beneficial effects of corticosteroids in reducing neurologic morbidity appear to vary with the age of the patient, (child or adult), the specific bacterial etiology, and even whether the patient lives in an industrialized country or in the developing world.

At present, evidence suggests that dexamethasone reduces hearing impairment in infants and children living in industrialized countries who have bacterial meningitis caused by H. influenzae type b. The effectiveness of dexamethasone in meningitis caused by other organisms remains unproved, although some studies of adults in industrialized countries with meningitis caused by S. pneumoniae report improved neurologic outcomes and reduced mortality. Dexamethasone does not appear to benefit children or adults with bacterial meningitis who live in developing countries, nor does it seem to benefit neonates with meningitis.

Thus, dexamethasone 0.15 mg/kg IV should be given before, or within 1 h after, antimicrobial therapy in children > 6 wk of age with meningitis caused by H. influenzae type b. The drug is continued q 6 h 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 wk of age.

For optimal efficacy, dexamethasone must be started at the time of diagnosis; this is not always possible, unless the Gram stain of the fluid or epidemiologic factors (eg, disease contact history) can yield an immediate etiologic diagnosis. In regions where children have been given routine H. influenzae type b and pneumococcal conjugate vaccines, bacterial meningitis caused by these organisms will be 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.

A conjugate pneumococcal vaccine effective against 13 serotypes, including > 90% of the pneumococcal serotypes that cause meningitis in infants, is recommended for all children beginning at 2 mo of age (see Table: Recommended Immunization Schedule for Ages 0–6 yr).

Routine vaccination with an H. influenzae type b conjugate vaccine also is highly effective and begins at age 2 mo.

The Advisory Committee on Immunization Practices (ACIP) recommends that infants > 6 wk who are at high risk of meningococcal disease receive a meningococcal conjugate vaccine. For infants not at high risk, routine meningococcal conjugate vaccination is recommended at age 11 or 12 yr (see Table: Recommended Immunization Schedule for Ages 7–18 yr). High-risk infants include those who

Two serogroup B meningococcal vaccines have been approved by the ACIP for use in children ≥10 yr 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 current ACIP meningococcal vaccine recommendations.

Antimicrobial chemoprophylaxis is necessary for

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

Not every health care practitioner 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 h of identification of the index patient); chemoprophylaxis given > 2 wk after exposure is likely of little to no value. Rifampin, ceftriaxone, and ciprofloxacin are appropriate drugs depending on the age of the contact (see Table: Recommended Chemoprophylaxis for High-Risk Contacts* of Children With Meningococcal or H. influenzae Type b Meningitis). For young children, oral rifampin or injectable ceftriaxone is preferred.

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:

Chemoprophylaxis is then recommended for each member of a household, as just defined, if that household also has

Complete immunization against H. influenzae type b is defined as having had at least 1 dose of Hib conjugate vaccine at age ≥ 15 mo, or 2 doses between 12 mo and 14 mo, or the 2- or 3-dose primary series for children < 12 mo with a booster dose at ≥ 12 mo.

In addition, if a preschool or child care center has had ≥ 2 cases of invasive Hib disease within 60 days among its members, 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 yr who are incompletely immunized against H. influenzae type b. Chemoprophylaxis should be given < 24 h after identification of the index patient; chemoprophylaxis given > 2 wk after exposure is likely of little to no value. Oral rifampin or injectable ceftriaxone is preferred, and ciprofloxacin is acceptable for older contacts (see Table: Recommended Chemoprophylaxis for High-Risk Contacts* of Children With Meningococcal or H. influenzae Type b Meningitis).