Clinical Features The clinical presentation of bacterial meningitis is often nonspecific and depends on the patient's age. Children with meningitis may present with fever and signs of a meningeal inflammation, such as severe and persistent headache, stiff and painful neck (nuchal rigidity), vomiting, and confusion. The degree of signs and symptoms often depends on the duration of the illness. Some less common symptoms include sluggishness, photophobia, skin rash, and dizzy spells. Petechiae and purpura are most commonly associated with N meningitidis and often begin in the lower extremities. Two clinical signs that may be present in patients with meningitis are Kernig and Brudzinski. A positive Kernig sign is when the patient is lying in the supine position with the hips and knees flexed at 90° and is unable to extend the knee beyond 135° without pain. A positive Brudzinski sign is when severe neck stiffness causes the patient's hips and knees to flex when the neck is flexed. Clinicians should keep in mind that the Kernig and Brudzinski signs, as well as nuchal rigidity, are not present in most cases of meningitis in adults and children. Generalized seizures occur in approximately 20% to 30% of patients prior to or within 48 hours of admission. Although temporary neurologic deficits may occur, these deficits resolve in most patients, and the patients are not at high risk for epilepsy. Patients at high risk for epilepsy are those with permanent neurologic deficits secondary to bacterial meningitis. Diagnosis The diagnosis of pediatric bacterial meningitis involves laboratory blood tests and analysis of cerebrospinal fluid (CSF). Blood tests should include a CBC, electrolyte panel, C-reactive protein, and coagulation factors. Diagnosis relies on CSF analysis. The Infectious Diseases Society of America (IDSA) bacterial meningitis guidelines recommend that lumbar puncture (LP) be performed on children with suspected meningitis. There are certain exceptions, including patients who are immunocompromised or have a history of selected neurologic conditions (i.e., CSF shunts, CNS trauma, or neurosurgery). In these cases, the patient should first receive a CT scan of the head and have normal findings confirmed prior to LP. The clinician should weigh the risk versus benefit of performing LP in a pediatric patient. Regardless of when the LP occurs, antibiotic treatment should be initiated immediately. In addition to the methods mentioned above, a Gram stain of CSF fluid also is performed.[15] The Gram stain is positive in about 90% and 80% of children with pneumococcal and meningococcal meningitis, respectively. In H influenzae andListeria meningitis, the Gram stain is positive in about 50% and 30% of patients, respectively. Generally, a patient whose CSF fluid has a high WBC count and a positive Gram stain has a poorer outcome. Molecular techniques such as polymerase chain reaction may be helpful in the diagnosis and resolution of bacterial meningitis. A rapid antigen-agglutination test may also be used in diagnosis. This option covers a wide range of organisms, such as Neisseria meningococcal serogroups, S pneumoniae,H influenzae, and Escherichia coli, but it is less sensitive. Because false-positive results have been reported with this method, many institutions do not use it. The rapid antigen-agglutination test may be most useful in patients who have been pretreated with antimicrobial therapy and whose CSF and Gram stain cultures are negative. The Bacterial Meningitis Score (BMS) may be used to determine the likelihood of bacterial and nonbacterial meningitis in infants and children older than 2 months. Criteria include positive CSF Gram stain, incidence of a seizure with illness, blood neutrophil count exceeding 10,000 cells/mm3, CSF neutrophil count greater than 10,000 cells/mm3, and CSF protein exceeding 80 mg/dL. Patients at low risk for bacterial meningitis have a score of 0, meaning that they lack the above criteria. A score of 1 point suggests that nonbacterial (aseptic) meningitis is less likely, and a score of >2 suggests that bacterial meningitis is more likely. A meta-analysis reported the BMS has a sensitivity of 99.3% and a specificity of 62.1%. The BMS may be helpful for determining the patient's risk of bacterial meningitis. Treatment Principles of Antimicrobial Therapy Empirical therapy is selected based on the common bacterium causing the meningitis. Once the pathogen is identified, specific treatment may be made based on the known organism. Additional considerations in selecting treatment depend on the drug's ability to penetrate the BBB. Certain characteristics of antimicrobials that permit easier penetration across the BBB include low molecular weight, simple chemical structure, high lipid solubility, low degree of protein binding, and low degree of ionization. For instance, vancomycin tends to have better penetration when the BBB is significantly damaged. Whether the antibiotic has concentration-dependent (aminoglycosides and fluoroquinolones) or time-dependent (vancomycin and beta-lactams) killing properties should also be considered. Antibiotics should be carefully deescalated once the organism has been identified. Antibiotics Globally, numerous organizations have treatment guidelines for bacterial meningitis, including the IDSA, the Canadian Paediatric Society, the National Institute for Health and Care Excellence, and the Meningitis Research Foundation. The 2004 IDSA guideline on bacterial meningitis is currently being updated, with publication expected in the autumn of 2016. Most of the recommendations provided here are from the IDSA guideline, although there is minimal variation between the various organizations. The initiation of empirical therapy for the management of bacterial meningitis should occur immediately following LP or when meningitis is suspected. Treatment is on an inpatient basis. Selection of empirical therapy depends on the most prevalent organisms for each age group , as well as on local resistance patterns. General recommendations often include a third-generation cephalosporin, such as ceftriaxone or cefotaxime. Ampicillin or penicillin G may be used against susceptible organisms. Drug resistance is a concern in the treatment of several organisms. Because of increasing apprehension regarding multidrug-resistant strains of S pneumoniae, penicillin is not recommended for empirical therapy. Instead, vancomycin is often added to the empirical regimen with a third-generation cephalosporin. The American Academy of Pediatrics (AAP) recommends initiating vancomycin with cefotaxime or ceftriaxone in all children aged 1 month and older with suspected meningitis and then deescalating once the organism is identified. The IDSA guidelines also recommend the addition of vancomycin whenever S pneumoniae is suspected. Rifampin, which has excellent CSF penetration, may be used in cases of cephalosporinresistant pneumococcal meningitis. Penicillin resistance has also been reported to occur with N meningitides; for this reason, penicillins are avoided and third-generation cephalosporins are first-line therapy for meningococcal meningitis. The duration of treatment has not been fully elucidated. A meta-analysis examining the duration of antibiotics did not find conclusive evidence to support either long or short courses of antibiotics in the treatment of pediatric bacterial meningitis. The current recommendations are based more on experience than on scientific evidence. Source
