1、Bacterial meningitisIntroductionn Bacterial meningitis is an inflammation of the leptomenings, usually causing by bacterial infection.n Bacterial meningitis may present acutely (symptoms evolving rapidly over 1-24 hours), subacutely (symptoms evolving over 1-7days), or chronically (symptoms evolving
2、 over more than 1 week).Introductionn Annual incidence in the developed countries is approximately 5-10 per 100000. n 30000 infants and children develop bacterial meningitis in United States each year. n Approximately 90 per cent of cases occur in children during the first 5 years of life.Introducti
3、onn Cases under age 2 years account for almost 75% of all cases and incidence is the highest in early childhood at age 6-12 months than in any other period of life.n There are significant difference in the incidence of bacterial meningitis by season. Etiologyn Causative organisms vary with patient a
4、ge, with three bacteria accounting for over three-quarters of all cases:n Neisseria meningitidis (meningococcus)n Haemophilus influenzae (if very young and unvaccinated)n Streptococcus pneumoniae ( pneumococcus)Etiologyn Other organisms n Neonates and infants at age 2-3 months n Escherichia colin B-
5、haemolytic streptococcin Staphylococcus aureusn Staphylococcus epidermidisn Listeria monocytogenesEtiologyn Elderly and immunocompromisedn Listeria monocytogenesn Gram negative bacterian Hospital-acquired infectionsn Klebsiellan Escherichia colin Pseudomonasn Staphylococcus aureusEtiologyn The most
6、common organisms n Neonates and infants under the age of 2monthsn Escherichia coli n Pseudomonas n Group B Streptococcusn Staphylococcus aureus Etiologyn Children over 2 monthsn Haemophilus influenzae type bn Neisseria meningitidisn Streptococcus pneumoniaen Children over 12 yearsn Neisseria meningitidisn Streptococcus pneumoniaeEtiologyn Major routes of leptomening infectionn Bacteria are mainly from blood.n Uncommonly, meningitis occurs by direct extension from nearly focus (mastoiditis, sinusitis) or by direct invasion (dermoid sinus tract, head trauma, meningo-myelocele).
