Meningitis pathogens

Polymerase chain reaction (PCR DNA amplification of the most common bacterial meningitis pathogens) may be useful to help exclude bacterial meningitis. 

The treatment of bacterial infections of the central nervous system highlights a number of important therapeutic considerations. Bacterial meningitis is caused by a variety of bacteria although their incidence varies with age. In the neonate, E. coli and group B streptococci account for the majority of infections, while in the preschool child H. influenzae is the commonest pathogen. Neisseria meningitidis has a... 

Bacterial meningitis is the most common cause of CNS infections. An epidemiologic review of bacterial meningitis in 1995 revealed that Streptococcus pneumoniae (pneumococcus) was the most common pathogen (47%), followed by Neisseria... 

Non-infectious causes of meningitis include malignancy, medications, autoimmune disease (such as lupus), and trauma.8,9 The most common pathogens causing bacterial meningitis, by age group and other risk factors, are found in Table 67-1. 

See Table 67-1 for empirical treatment recommendations. cSee text for specific recommendations for use of adjunctive dexamethasone in adults with bacterial meningitis. dSee Table 67-3 for pathogen-based definitive treatment recommendations. (Adapted, with permission, ref. 14.)... 

Empirical therapy for postoperative infections in neurosurgical patients (including patients with CSF shunts) should include vancomycin in combination with either cefepime, ceftazidime, or meropenem. Linezolid has been reported to reach adequate CSF concentrations and resolve cases of meningitis refractory to vancomycin.35 However, data with linezolid are limited. The addition of rifampin should be considered for treatment of shunt infections. When culture and sensitivity data are available, pathogen-directed antibiotic therapy should be administered. Removal of infected devices is desirable aggressive antibiotic therapy (including high-dose intravenous antibiotic therapy plus intraventricular vancomycin and/or tobramycin) may be effective for patients in whom hardware removal is not possible.36... 

Assess the patient s signs, symptoms, and risk factors for meningitis. Do these offer any clues to the offending pathogen ... 

Haemophilus influenzae is a bacterial respiratory pathogen that causes a wide spectrum of disease ranging from colonization of the airways to bacterial meningitis. It causes considerable morbidity and mortality, especially in children less than 5 years of age. H. influenzae is either encapsulated or unencapsulated. The encapsulated strains can be further differentiated into six antigenically distinct serotypes, a through f. H. influenzae type b was primarily found in cerebrospinal fluid and blood of children with meningitis, while the unencapsulated strains were found in the upper respiratory tract of adults. Before the introduction of the vaccine, H. influenzae was responsible for 20,000 to 25,000 cases of invasive disease annually and was the most common cause of bacterial meningitis. Since the introduction of the vaccine, invasive disease due to H. influenzae type b has been nearly eliminated. 

The critical first step in the acquisition of acute bacterial meningitis is nasopharyngeal colonization of the host by the bacterial pathogen. The bacteria first attach themselves to nasopharyngeal epithelial cells and are then phagocytized into the host s bloodstream. 

TABLE 36-2 1 Bacterial Meningitis Most Likely Pathogens ... 

Empiric antimicrobial therapy should be instituted as soon as possible to eradicate the causative organism (Table 36-2). Antimicrobial therapy should last at least 48 to 72 hours or until the diagnosis of bacterial meningitis can be ruled out. Continued therapy should be based on the assessment of clinical improvement, cultures, and susceptibility testing results. Once a pathogen is identified, antibiotic therapy should be tailored to the specific pathogen. 

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