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Similar to Laboratory diagnosis of meningitis
Laboratory diagnosis of meningitis
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- 2. • These areamong the most important problems in medicine today • Common acute infections of the nervous system include: Acute bacterial meningitis Viral meningitis Brain abscess Empyema Encephalitis • Each may present with a non-specific prodrome of fever and headache.
- 3. • Inflammatory processof leptomeninges and CSF within the subarachnoid space. • Meningoencephalitis combines this with inflammation of brain parenchyma. • Meningitis is usually caused by a infection - Acute pyogenic (bacterial)or aseptic (viral) and Chronic(usually due to tuberculous, spirochetal or cryptococcal).
- 4. ACUTE BACTERIAL • Acutepurulent infection within the subarachnoid space. • Associated with CNS inflammatory reactions that may result in decreased consciousness, seizures, raised ICP etc VIRAL • Usually present with headache, fever and signs of meningeal irritation coupled with inflammatory CSF. • The headache of viral meningitis is often frontal or retro-orbital associated with photophobia and pain on eye movement.
- 5. • CSF EXAMINATION •HISTOPATHOLOGY • LATEX AGGLUTNATION • POLYMERASE CHAIN REACTION • VIRAL CULTURE • RAPID DIAGNOSTIC TESTS (RDT) • SEROLOGIC STUDIES • OTHER LAB STUDIES
- 6. • Laboratory examinationof the CSF is usually the first step to confirm the presence of meningitis. • Cytological examination should precede centrifugation and heating of CSF.
- 7. • The typicalprofile: CSF opening pressure: 50–180 mmH2O Glucose: 40–85 mg/dL. Protein (total): 15–45 mg/dL. Leukocytes (WBC): 0–5/µL (adults / children); up to 30/µL (newborns). Culture: sterile. Gross appearance: Normal CSF is clear and colorless. Differential: 60–70% lymphocytes; up to 30% monocytes and macrophages; other cells 2% or less.
- 8. • • • • • • Glucose (mg/dL): Protein (mg/dL) WBCs(cells/µL) Cell differential: Culture: Opening Pressure Normal (> 40 mg/dL.) <100 mg/dL (moderate increase) < 100 cells/µL. Early: neutrophils. Late: lymphocytes. Negative Usually normal
- 9. • • • • • • Glucose (mg/dL): Protein (mg/dL): WBCs(cells/µL): Cell differential: Culture: Opening Pressure: Normal to marked decrease. <40 mg/dL. (Marked increase) > 250 mg/dL. >500 (usually > 1000). Early: May be < 100. Predominance of Neutrophils (PMNs) Positive Elevated
- 11. • Neutrophils fillthe subarachnoid space in severely affected areas and are found predominantly around the leptomeningeal blood vessels in the less severe cases.
- 14. • Positive reaction:agglutination (or visible clumping) of the latex particles and slight clearing of the suspension occurs within 2-10 minutes . • Negative reaction: the suspension remains homogenous and slightly milky in appearance.
- 15. • Amplification ofvirus specific DNA or RNA from CSF using PCR amplification has become the single most effective method for diagnosing CSF viral infections. • It is a highly sensitive and specific test since only trace amounts of the infecting agent's DNA is required. • It may identify bacteria in bacterial meningitis and may assist in distinguishing the various causes of viral meningitis.
- 16. • The sensitivityof CSF cultures for the diagnosis of viral meningitis is poor in comparison to the detection of bacterial meningitis. • Viruses may also be isolated from throat swabs, blood and urine. • Enterovirus and adenoviruses maybe found in the feces.
- 20. • Crucial diagnostictool • Serum antibody detection is less useful for viruses with high prevalence rates in the general population. • For viruses with low prevalence rates , diagnosis of acute viral infection can be made by documenting • Seroconversion between acute phase and convalescent sera. • The documentation of synthesis of virus specific antibodies in CSF is more useful than serum serology alone.
- 21. • RDTs havebeen developed for direct testing of CSF specimens without prior heat or centrifugation. • The test is based on the principle of vertical flow immunochromatography. • Gold particles and nitrocellulose membranes are coated with monoclonal antibodies to capture soluble serogroup-specific polysaccharide antigens in the CSF.
- 22. • Appearance ofred lines on the dipsticks will indicate whether one of the four meningococcal serogroups has been detected in the CSF. • The upper line on the dipstick is the positive control and should always be present. • If the CSF is positive for one of the serogroups, a lower red line will also be present. The position of that red line indicates the specific serogroup based on the RDT that was tested. • A negative result consists of a single upper pink control line only.
- 24. • CBC (completeblood count) & DLC (differential leucocyte count) • Liver and Renal function tests • ESR (erythrocyte sedimentation rate) • C- Reactive protein • Electrolytes etc • MRI and CT are not necessary in patients with uncomplicated meningitis. • They may be performed in patients with altered consciousness, seizures etc