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causative organisms, diagnosis and treatment of meningitis.


  • Meningitis G e n e r a l O v e r v i e w Siddharth Bansal MBBS Gauhati Medical College 9/5/2013 1
  • Clinical description Meningitis is a disease caused by the inflammation of the protective membranes covering the brain and spinal cord known as the meninges. The inflammation is usually caused by an infection of the fluid surrounding the brain and spinal cord. Meningitis can be life-threatening because of the inflammation's proximity to the brain and spinal cord; therefore the condition is classified as a medical emergency. 9/5/2013 2
  • Meninges The meninges is the system of membranes which envelops the central nervous system. It has 3 layers: 1. Dura mater 2. Arachnoid mater 3. Pia mater Subarachnoid space - is the space which exists between the arachnoid and the pia mater, which is filled with cerebrospinal fluid. 9/5/2013 3
  • Causes of Meningitis - Bacterial - Viral - Fungal - Ricketsial (Rocky mountain spotted fever) - Parasitic/ protozoal - Physical injury - Cancer - Certain drugs ( mainly, NSAIDS) Severity/treatment of illnesses differ depending on the cause. Thus, it is important to know the specific cause of meningitis. 9/5/2013 4
  • Bacterial - Haemophilus influenzae - Listeria - Meningococcus - Mumps - Pneumococcus - Group A Streptococcus - Group B Streptococcus 9/5/2013 5
  • Premature babies and newborns (< 3 months): group B streptococci, Listeria monocytogenes(serotype IVb). Older children: Neisseria meningitidis and Streptococcu pneumoniae (serotypes 6, 9, 14, 18 and 23) and those under five by Haemophilus influenzae type B Adults: N. meningitidis and S. pneumoniae (80% of all cases) of bacterial meningitis, with increased risk of L. monocytogenes (>50yrs) Bacterial 9/5/2013 6
  • Haemophilus influenzae Meningitis Occurs mostly in children (6 months to 4 years). Gram-negative aerobic bacteria, normal throat microbiota Capsule antigen type b Prevented by Hib vaccine Reduction in H.influenzae meningitis due to development of Hib vaccine 9/5/2013 7
  • Neisseria Meningitis, (Meningococcal Meningitis) Gram-negative aerobic cocci, capsule 10% of people are healthy nasopharyngeal carriers Begins as throat infection, rash Serotype B is most common in the United States Vaccination recommended for college students. 9/5/2013 8
  • Streptococcus pneumoniae Meningitis, Pneumococcal Meningitis Gram-positive diplococci 70% of people are healthy nasopharyngeal carriers Most common in children (1 month to 4 years) Mortality: 30% in children, 80% in elderly Prevented by vaccination 9/5/2013 9
  • Viral - Enterovirus (coxsackie, echovirus) - Arboviral (mosquito-borne diseases) - Influenza - Herpes simplex virus type2 ( especially in infants) - Varicella zoster - HIV - Mumps - measles 9/5/2013 10
  • Viral Meningitis Incubation period : 3 to 6 days. Duration of the illness : approx 7 to 10 days. Milder and occurs more often than bacterial meningitis. Affects children and adults under age 30. Most infections occur in children under age 5. Most viral meningitis is due to enteroviruses, that also can cause intestinal illness. Diagnosed by laboratory tests of a patients spinal fluid 9/5/2013 11
  • Fungal Cryptococcus Coccidiodes Histoplasma Mucormycosis Aspergillus Candida (yeasts) Parasitic/protozoal Angiostrongylus Toxoplama Hydatid Amoeba Plasmodium Cysticercosis 9/5/2013 12
  • Symptoms can be the same for Viral and Bacterial 9/5/2013 13
  • COMPLICATIONS Brain damage Buildup of fluid between the skull and brain (subdural effusion) Hearing loss Hydrocephalus Seizures 9/5/2013 14
  • DIAGNOSIS Tests that may be done include: For any patient who is suspected of having meningitis, lumbar puncture ("spinal tap") is done for CSF examination . Blood culture Chest x-ray CSF examination for cell count, glucose, and protein CT scan of the head Gram stain, other special stains, and culture of CSF 9/5/2013 15
  • DIAGNOSIS (contd..) Specimen: CSF, blood, urine culture Blood tests and imaging Blood tests are performed for markers of inflammation (e.g. C- reactive protein, complete blood count), as well as blood cultures. Most important is CSF examination by LP. Blood tests are done when it is C/I In severe forms of meningitis, monitoring of blood electrolytes may be important; for example, hyponatremia is common in bacterial meningitis. 9/5/2013 16
  • DIAGNOSIS (contd..) Lumbar puncture A lumbar puncture is done by positioning the patient, usually lying on the side, applying local anesthetic, and inserting a needle into the dural sac. CT or MRI scan is recommended prior to the lumbar puncture. The CSF sample is examined for presence and types of white blood cells, red blood cells, protein content and glucose level. Gram staining of the sample may demonstrate bacteria in bacterial meningitis (60% cases). C/I: Mass in the brain (tumor or abscess) or the intracranial pressure (ICP) is elevated. Gram stain of meningococci from a culture showing Gram negative (pink) bacteria, often in pairs 9/5/2013 17
  • CSF findings in different forms of meningitis Type of meningitis Glucose Protein Cells Acute bacterial low high PMNs often > 300/mm Acute viral normal normal or high mononuclear < 300/mm Tuberculous low high mononuclear and PMNs, < 300/mm Fungal low high < 300/mm Malignant low high usually mononuclear 9/5/2013 18
  • Latex agglutination - The clumping of cells such as bacteria or RBCs in the presence of an antibody. The antibody or other molecule binds multiple particles and joins them, creating a large complex. Positive in meningitis caused by Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, Escherichia coli and group B streptococci. Serotyping - Group of microorganisms classified together based on their cell surface antigens (virulence, lipopolysaccharides in Gram-negative bacteria), presence of an exotoxin or other characteristics which differentiate two members of the same species. DIAGNOSIS (contd..) 9/5/2013 19
  • Limulus amebocyte lysate (LAL): An aqueous extract of blood cells (amoebocytes) from the horseshoe crab, (Limulus polyphemus). LAL reacts with bacterial endotoxin or lipopolysaccharide (LPS), which is a membrane component of Gram negative bacteria. Polymerase chain reaction(PCR) is a technique used to amplify small traces of bacterial DNA DIAGNOSIS (contd..) 9/5/2013 20
  • Kernigs sign - is assessed with the patient lying supine, with the hip and knee flexed to 90 degrees. In a patient with a positive Kernig's sign, pain limits passive extension of the knee. Brudzinski signs -A positive Brudzinski's sign occurs when flexion of the neck causes involuntary flexion of the knee and hip. 9/5/2013 21
  • Skin findings: Nonspecific blanching, erythematous, maculopapular rash to a petechial or purpuric rash. **Approximately 6% of affected infants and children show signs of disseminated intravascular coagulopathy and endotoxic shock. These signs are indicative of a poor prognosis. 9/5/2013 22
  • Treatment Antibiotics for bacterial meningitis :Type vary depending on the bacteria causing the infection. Antibiotics are not effective in viral meningitis. Other medications and intravenous fluids will be used to treat symptoms such as brain swelling, shock, and seizures. Prevention Haemophilus vaccine (HiB vaccine) in children. The pneumococcal conjugate vaccine is now a routine childhood immunization and is very effective at preventing pneumococcal meningitis. Household members and others in close contact with people who have meningococcal meningitis should receive preventive antibiotics. 9/5/2013 23
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