Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content + Print Section ++ For further information, see CMDT Part 33-03: Pneumococcal Infections + Key Features Print Section ++ ++ Essentials of Diagnosis ++ Fever, headache, altered mental status Meningismus Gram-positive diplococci on Gram stain of cerebrospinal fluid; counterimmunoelectrophoresis may be positive in partially treated cases ++ General Considerations ++ Streptococcus pneumoniae is the most common cause of meningitis in adults and the second most common cause of meningitis in children over the age of 6 years Head trauma, with cerebrospinal fluid leaks, sinusitis, and pneumonia may precede it Penicillin-resistant strains may cause meningitis ++ Demographics ++ Until 2000, S pneumoniae infections caused 100,000–135,000 hospitalizations for pneumonia, 6 million cases of otitis media, and 60,000 cases of invasive disease, including 3300 cases of meningitis Disease figures are now changing due to conjugate vaccine introduction + Clinical Findings Print Section ++ ++ Symptoms and Signs ++ Rapid onset, with fever, headache, and altered mentation Pneumonia may be present Compared with meningitis caused by the meningococcus Pneumococcal meningitis lacks a rash Obtundation, focal neurologic deficits, and cranial nerve palsies are more prominent features and may lead to long-term sequelae ++ Differential Diagnosis ++ Meningitis due to other causes, eg, meningococcus, Listeria, aseptic Subarachnoid hemorrhage Encephalitis "Neighborhood reaction" causing abnormal cerebrospinal fluid, such as Brain abscess Epidural abscess Vertebral osteomyelitis Mastoiditis Sinusitis Brain tumor Dural sinus thrombosis Noninfectious meningeal irritation Carcinomatous meningitis Sarcoidosis Systemic lupus erythematosus Drugs (eg, nonsteroidal anti-inflammatory drugs, trimethoprim-sulfamethoxazole) Pneumonia Shigellosis + Diagnosis Print Section ++ ++ Laboratory Tests ++ See Table 30–1 Cerebrospinal fluid Typically has > 1000 white blood cells per microliter, over 60% of which are polymorphonuclear leukocytes Glucose concentration is < 40 mg/dL (< 2.22 mmol/L), or < 50% of the simultaneous serum concentration Protein usually exceeds 150 mg/dL (1500 mg/L) Gram stain shows gram-positive cocci in up to 80–90% of cases In untreated cases, blood or cerebrospinal fluid cultures are almost always positive Fifty percent rate of bacteremia Antigen detection tests may occasionally be helpful in establishing the diagnosis in the patient who has been partially treated and in whom cultures and stains are negative + Treatment Print Section ++ ++ Medications ++ See Tables 30–5 and 30–2 Give antibiotics as soon as the diagnosis is suspected If lumbar puncture must be delayed (eg, while awaiting results of an imaging study to exclude a mass lesion), ceftriaxone, 4 g intravenously, should be given after blood cultures (positive in 50% of cases) have been obtained If gram-positive diplococci are present on the Gram stain, then vancomycin, 30 mg/kg/day intravenously in two divided doses, should be administered in addition to ceftriaxone until the isolate is confirmed not to be penicillin-resistant Once susceptibility to penicillin has been confirmed, penicillin, 24 million units daily intravenously in six divided doses, or ceftriaxone, 4 g/day as a single dose or as two divided doses, is recommended For severe penicillin allergy, chloramphenicol, 50 mg/kg every 6 hours, is an alternative (failures have occurred with penicillin-resistant strains) Duration of therapy is 10–14 days in documented cases The best therapy for penicillin-resistant strains is not known. Susceptibility testing is essential If the minimum inhibitory concentration (MIC) of ceftriaxone or cefotaxime is ≥ 0.5 mcg/mL, single-drug therapy with either of these cephalosporins is likely to be effective When the MIC is ≤ 1 mcg/mL, treatment with a combination of ceftriaxone, 2 g every 12 hours, plus vancomycin, 30 mg/kg/day in two divided doses, is recommended Give 10 mg of dexamethasone intravenously immediately prior to or concomitantly with the first dose of appropriate antibiotic and every 6 hours thereafter for a total of 4 days + Outcome Print Section ++ ++ Follow-Up ++ If a patient with a penicillin-resistant organism has not responded to a third-generation cephalosporin, repeat lumbar puncture is indicated to assess the bacteriologic response ++ Complications ++ Hearing loss Residual neurologic deficit ++ Prevention ++ Pneumococcal vaccine recommendations (Table 30–7) ++ Prognosis ++ Patients presenting with depressed levels of consciousness have a worse outcome Dexamethasone administered with antibiotic to adults with meningitis has been associated with a 60% reduction in mortality and a 50% reduction in unfavorable outcome, primarily in patients with pneumococcal meningitis ++ When to Refer ++ Consider early referral to an infectious disease specialist ++ When to Admit ++ All patients with suspected bacterial meningitis + References Print Section ++ + +Costerus JM et al. Community-acquired bacterial meningitis. Curr Opin Infect Dis. 2017 Feb;30(1):135–41. [PubMed: 27828810] + +Mora Carpio AL et al. Pneumococcal bacteremia and meningitis. N Engl J Med. 2018 Nov 22;379(21):2063. [PubMed: 30462944]