Meningitis Overview and Treatment Guidelines

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Questions and Answers

What type of meningitis is typically considered more severe?

Acute bacterial meningitis (correct)

Aseptic meningitis

Shunt associated meningitis

Chronic meningitis

Which of the following is not a potential source of infection for meningitis?

Trauma or surgery on the head

Airborne respiratory droplets (correct)

Bacteraemia

Contiguous infection

Which of the following characters is a predisposing factor for nasopharyngeal colonization leading to bacterial meningitis?

High-fat diet

Smoking (correct)

Excessive physical activity

Inadequate sleep

What type of meningitis requires urgent specific treatment?

Acute bacterial meningitis Signup and view all the answers

Which of the following agents can cause acute bacterial meningitis?

Bacteria Signup and view all the answers

What is the recommended empiric treatment for patients aged 65 years and older with alcohol abuse and debilitating diseases?

Cefotaxime/ceftriaxone plus ampicillin with or without vancomycin Signup and view all the answers

Which of the following vaccines is NOT available for Group B meningitis?

Group B conjugate vaccine Signup and view all the answers

Which treatment is suggested for immunocompromised patients?

Ampicillin plus cefotaxime with or without vancomycin Signup and view all the answers

What is included in the NPI schedule in SL for meningitis prevention?

Bivalent vaccine for Haemophilus influenzae type b Signup and view all the answers

What is the role of chemoprophylaxis in meningitis prevention?

It prevents secondary cases among close contacts Signup and view all the answers

What is the characteristic feature distinguishing acute meningitis from chronic meningitis?

Acute onset within hours to days Signup and view all the answers

Which clinical feature is part of the classic triad seen in patients with meningitis?

Fever Signup and view all the answers

What does a positive Kernig's sign indicate in a patient suspected of having meningitis?

Flexing of hips and knees when neck is flexed Signup and view all the answers

What significant decrease in incidence was observed with the introduction of vaccination against Haemophilus influenzae type b?

90% Signup and view all the answers

Which of the following is NOT typically associated with Meningococcal Septicaemia?

Abdominal cramps Signup and view all the answers

What is the primary diagnostic method for identifying viral infections in the CNS?

Organism specific PCR in CSF Signup and view all the answers

Which organism is NOT typically associated with brain abscesses?

Streptococcus pneumoniae Signup and view all the answers

What is the common clinical feature of a brain abscess?

Headache Signup and view all the answers

Which of the following is considered a predisposing factor for developing a brain abscess?

Chronic sinusitis Signup and view all the answers

What is the role of IgM antibodies in viral serology diagnostics?

Indicate a current active infection Signup and view all the answers

Which treatment is appropriate for managing a brain abscess?

Surgery and antibiotics Signup and view all the answers

What does a four fold rising titre of virus specific IgG antibodies indicate?

A recent or active infection Signup and view all the answers

Which bacterium is primarily associated with acute bacterial meningitis?

Neisseria meningitidis Signup and view all the answers

Which condition should be considered first in the differential diagnosis for the patient?

Meningitis/encephalitis Signup and view all the answers

What clinical sign in the patient strongly supports a diagnosis of meningitis?

Neck stiffness Signup and view all the answers

What is a potential complication of untreated meningitis?

Septic shock Signup and view all the answers

What observation would not typically support a diagnosis of diabetic ketoacidosis?

Blood sugar is not excessively high Signup and view all the answers

Why is early diagnosis and treatment essential in cases of suspected CNS infection?

To prevent rapid deterioration and complications Signup and view all the answers

Which of the following findings would be least likely in a patient with hyperglycemic hyperosmolar nonketotic coma?

Ketoacidosis present Signup and view all the answers

What is a common clinical presentation indicating a CNS infection?

Severe headache Signup and view all the answers

What blood glucose level is indicative of poorly controlled diabetes in this patient?

$280 mg/dL$ Signup and view all the answers

What is the primary mechanism by which pathogens evade the immune response in the respiratory mucosal epithelium?

Secretion of IgA proteases Signup and view all the answers

What effect does bacterial infection have on the blood-brain barrier in the case of meningitis?

Increases permeability Signup and view all the answers

Which of the following is a common causative organism of bacterial meningitis in individuals over 50 years of age?

Listeria monocytogenes Signup and view all the answers

What is a potential consequence of inflammation of the meninges due to bacterial meningitis?

Development of cerebral hypoxia Signup and view all the answers

What is the approximate mortality rate associated with Streptococcus pneumoniae infections?

20-30% Signup and view all the answers

Which serogroups of Neisseria meningitidis account for most cases of meningococcal meningitis?

A, B, C, and W135 Signup and view all the answers

What is a risk factor for developing bacterial meningitis that is associated with head trauma?

Basilar skull fracture Signup and view all the answers

What cellular component is notably low in the cerebrospinal fluid during bacterial meningitis?

Antibodies Signup and view all the answers

What is a result of the presence of bacterial toxins in the cerebrospinal fluid?

Cerebral oedema Signup and view all the answers

Which organism is more likely to cause meningitis in patients with an immunocompromised state?

Streptococcus pneumoniae Signup and view all the answers

Study Notes

Case History

A 59-year-old obese woman with poorly controlled diabetes had a fever for one day.
The next morning, she was unresponsive and brought to the hospital.
She took her usual oral hypoglycemic medication and atorvastatin the previous night and ate dinner.
She had no reported history of seizures.
Physical examination revealed fever (38.4°C), Glasgow Coma Scale (GCS) of 6/15 (M-3, V-2, E-1), pulse rate of 116/min, blood pressure (BP) of 120/70, respiratory rate of 20/min, clear lungs, dual rhythm heart, and no murmurs.
Neck stiffness was present, but no focal neurological deficit.
Complete Blood Serum (CBS) was 280 mg/dL.

Differential Diagnosis

Meningitis or encephalitis?
Diabetic ketoacidosis?
Hyperglycemic hyperosmolar nonketotic coma?
Stroke?

Differential Diagnosis - Further Details

Diabetic ketoacidosis?: Patient is not dyspneic. CBS is not very high.
Hyperglycemic hyperosmolar nonketotic coma?: In HHNC, blood sugar is very high.
Stroke?: No focal weakness. Fever is present.

Meningitis/Encephalitis

Meningitis/encephalitis should be first considered in the differential diagnosis.
Reasons include fever, history of diabetes (poorly controlled), and neck stiffness.
Rapid deterioration is possible, and prompt diagnosis/treatment is crucial to prevent complications and death.
This is a medical emergency.

CNS Infections: Overview

A diagram showing the layers of the meninges is present.
This describes the normal structures of the central nervous system.

Learning Objectives

The learning objectives include: classifying cerebral infections in children and adults, describing the pathophysiology of CNS infections, listing aetiologies, describing clinical presentations, listing investigation procedures, and outlining immediate management.

Defense Mechanisms

A diagram depicting the layers of the body protecting the brain is shown.

Defense Mechanisms...

A diagram showing the cerebral structures and the blood-brain barrier is present.

Classification of Cerebral Infections

Meningitis, acute bacterial, aseptic, shunt-associated, chronic meningitis, encephalitis, and brain abscess are classified.
The infected agents for each type of infection are also listed. This includes viruses, bacteria, fungi, protozoa, and helminthes.

Meningitis

Inflammation of the meninges is the definition of meningitis.
Bacterial meningitis is more severe but less common than viral meningitis.
Acute bacterial meningitis is a life-threatening infection that needs immediate treatment.
It's a medical emergency.

Pathophysiology of Meningitis

Sources of infection include bacteraemia, contiguous infections (e.g., sinusitis, otitis media, dental abscess), head trauma/surgery (e.g., compound fracture, craniotomy), ventricular drains/CSF shunts/lumbar puncture, and immune deficiencies (e.g., HIV/AIDS, immunosuppressive treatment, alcohol abuse, diabetes mellitus).

Pathogenesis of Bacterial Meningitis

Factors that predispose to infections like smoking and concurrent viral infection are discussed.
The process of infection includes nasopharyngeal colonization and local invasion.
Also, bacterial evasion of complement activation and phagocytosis.
Further, CSF entry and multiplication of the bacteria, low levels of antibodies and complement proteins are all shown.
Lastly, inflammation of the meninges.

Pathogenesis of Bacterial Meningitis - 2

Bacterial infection leads to increased blood-brain barrier permeability, cerebral edema, and bacterial toxins in the CSF.
Cerebral hypoxia, exudates throughout the CSF, and potential damage to cranial nerves.
The infection may also block CSF drainage pathways, resulting in obstructive hydrocephalus.

Aetiological Agents - According to Age

Causative organisms are categorized by age groups (<1 month, 1 month-2 years, 2-50 years, >50 years). (examples Streptococcus agalactiae, Escherichia coli, Listeria monocytogenes, etc.)

Aetiological Agents - According to Risk Factors

Organisms associated with different risk factors (immunocompromised state, basilar skull fracture, head trauma/neurosurgery, etc.) are categorized.

Streptococcus Pneumoniae

Gram-positive diplococci.
Mortality rate of 20-30%.
High incidence in children with cochlear implants.
Serious infection in individuals with various underlying conditions, particularly splenectomy/asplenic states.

Neisseria Meningitidis

Gram-negative intracellular diplococci.
Overall mortality rate of 3% (13%).
Less common in Sri Lanka.
Annual outbreaks in the sub-Saharan meningitis belt.

Haemophilus Influenzae Type b (Hib)

Pleomorphic gram-negative bacilli.
Overall mortality rate is 3% to 7%.
Cases have markedly decreased due to the introduction of vaccination.

Clinical Presentation of Meningitis - Acute

Characterized by the onset of meningeal irritation, potentially within hours to a few days.

Clinical Presentation of Meningitis - Chronic

Characterized by insidious onset over weeks to months.
This can occur in various forms including tuberculous, fungal, and syphilitic meningitis.

Clinical Features of Meningitis

The features of fever, neck stiffness, altered consciousness, headache, vomiting, and inability to tolerate bright light (photophobia) are listed.

Clinical Features of Meningitis - Further

Kernig's sign (pain with leg raising and knee flexion).
Brudzinski's sign (severe neck stiffness causing hip and knee flexion).
Focal neurological signs.
Convulsions.
Rash (sometimes).

Meningococcal Septicaemia - Waterhouse-Friderichsen Syndrome

Purpuric skin rash is a distinctive symptom.
Bilateral adrenal haemorrhage is also present.

Morphology of Meningitis

Meningeal vessel engorgement.
Purulent exudate over the brain surface and in the basal areas.
Pneumococcal meningitis is usually seen in the cerebral convexities near the sagittal sinus.
Pus tracts often follow blood vessels.

Microscopy of Meningitis

Abundant neutrophils around blood vessels in subarachnoid space during untreated cases.
Inflammatory cells can infiltrate meningeal veins and enter into brain parenchyma.
Hemorrhagic cerebral infarctions may occur due to vasculitis and thrombosis.

Lumbar Puncture (LP)

A common procedure for obtaining cerebrospinal fluid (CSF) from the spinal cord.
It's the gold standard for diagnosing meningitis, subarachnoid hemorrhage, and certain neurological disorders.
It is also used for measuring intracranial pressure, and administering medications/diagnostic agents.

Lumbar Puncture for CSF Analysis

A sterile procedure for withdrawing CSF from the subarachnoid space (most commonly L3-4 or L4-5). Spinal landmarks are used to avoid damage during the procedure.

Order for Spinal Needle Traversal

Sequence detailing the passage of the spinal needle through the following layers: skin, subcutaneous tissue, supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura, arachnoid, and subarachnoid space.

CSF Sample Collection

CSF is typically collected into 4 tubes to facilitate different analyses.
Measurements include CSF sugar, microbiological investigations (including culture, ABST, and AFB smear), full report (cytology, protein), and reserving one tube for further tests such as viral studies.

Contraindications to Performing a LP

Skin infection near the LP site.
Central nervous system lesion or spinal mass.
Increased intracranial pressure.
Platelet count is less than 20,000mm3.
Use of unfiltered heparin or low molecular weight heparin within the preceding 24 hours.
Coagulopathies (e.g., hemophilia, von Willebrand disease).
Vertebral trauma.

Indications for Neuroimaging (CT Scan) Before LP

Focal neurological signs or indications of brain shift (e.g., significant brain swelling, which could lead to further potentially fatal conditions like cerebral herniation).
Presence of papilledema (inability to examine the fundi) and especially in cases with prolonged or short durations of symptoms).
Continuous or uncontrolled seizures.
Glasgow Coma Scale (GCS) of 12 or less.

Normal CSF

Clear, colorless appearance.
Glucose (40-80 mg/dL), usually 2/3 of blood glucose.
Total protein (15-45 mg/dL).
Leukocytes (WBC): 0-5/µL (adults/children), up to up to 19/µL (infants), and potentially higher numbers in newborns.
Absence of red blood cells unless from traumatic taps.

Characteristic CSF Changes

Detailed table outlining cell types, counts, glucose, protein, and Gram stain outcomes in various CNS infections (normal, viral, bacterial, tuberculous, and fungal).

Microbiological Basis of Treatment

Intravenous antibiotic therapy is the standard approach.
Factors considered when choosing an antibiotic include its ability to penetrate the CSF, activity in purulent CSF, bactericidal activity, and concentration in CSF.
Duration of treatment depends on the identified organism.

Empirical Treatment for Bacterial Meningitis

A table detailing empirically suggested antimicrobial therapy for different age groups based on common causative agents and CNS issues (shunts).

Empirical Treatment

Further table encompassing specific empiric treatments based on distinct risk factors like age, presence of comorbid conditions, recent trauma, or compromised immune systems.

Prevention of Meningitis

Vaccines for various pathogens responsible for meningitis, including Hib, pneumococcal, and meningococcal vaccines, are suggested for population-wide protection against meningitis. Types of vaccines and patient populations for protection are further delineated.

Chemoprophylaxis

Chemoprophylaxis (to prevent secondary cases of infection) is recommended for individuals (particularly those in close contact) with infections like those associated with Haemophilus influenzae type b and meningococcal infections.

Encephalitis

An acute inflammation/infection of the brain parenchyma.
Characterized by decreased mentation (abnormal state of consciousness), potentially with or without seizures, commonly presenting early with minimal meningeal signs.

Routes of Acquiring Brain Infection

Haematogenous route (commonest): including arboviruses, enteroviruses, bacteria (e.g., rickettsia).
Neuronal retrograde dissemination: for pathogens like HSV, VZV, rabies.
Postinfectious encephalomyelitis (immune-mediated): including measles and rubella.

Clinical Features of Encephalitis

Neuropsychiatric symptoms (e.g., abnormal behavior, hallucinations, personality changes, agitation, psychosis).
Focal neurological signs, focal seizures.
Altered consciousness
Sudden onset of fever and headache.

Causative Organisms in Encephalitis

Table of various viral agents associated with encephalitis, encompassing Herpes simplex virus, Japanese encephalitis, West Nile virus, HIV, Varicella-zoster virus, St. Louis encephalitis, equine encephalitis, and other non-viral pathogens, including Listeria monocytogenes, or various types of bacteria and rickettsia.

Herpes Simplex Encephalitis

Caused by herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2).
HSV-1 is associated with oral, eye, and CNS infections.
HSV-2 frequently causes genital infections (though can cause CNS infections).
Pathogenesis involves reactivation in trigeminal ganglia and transmission to the temporal lobe through nerve fibers.
One-third of cases are primary infections, developing during the neonatal period.

Herpes Simplex Virus – Structure

Diagram showing the structure of HSV, including nucleocapsid, tegument, and lipid bilayer envelope, and surface glycoproteins.

Microbiological Investigations for Encephalitis

CSF analysis—the use of PCR, virus-specific IgM antibody detection, and virus isolation for etiological confirmation.
Blood serological tests, including identification of virus-specific IgM, detecting rising fourfold titres in paired sera, and testing for virus-specific IgG antibodies.

Treatment of Encephalitis

Intravenous acyclovir for 14 days is the standard treatment for HSV encephalitis.
Duration is extended to 21 days for immunocompromised patients.
Empirical treatment is crucial for encephalitis given potentially life-threatening nature, particularly when treating HSV encephalitis.
Early treatment prevents mortality and morbidity.

Japanese Encephalitis

Caused by a Flavivirus.
Transmission is primarily via infected mosquitoes (Culex, especially C. tritaeniorhynchus).
Hosts/vectors include domestic pigs and birds, with humans being incidental hosts.
Transmission typically occurs in flooded rice fields and paddy areas.
The disease is most prominent during monsoon season from November to February.

Microbiological Investigations for JE

Specific IgM antibodies detection in CSF, performed early post-infection.
Presence of antibody in CSF confirms the virus infected the central nervous system.
A single sample of CSF is typically sufficient for diagnosis, with approximately 70% positivity at admission.
Testing for rising serum titer of JE specific antibodies in paired sera, molecular diagnostic tests and PCR testing of CSF.

Treatment of JE

Treatment is mostly supportive and symptomatic due to lack of a specific antiviral therapy.

Brain Abscess

A focal, localized infection in the brain parenchyma that forms pus, surrounded by a vascular capsule.
A variety of predisposing factors including chronic middle ear infection, dental abscess, chronic sinusitis, congenital heart disease, head trauma, and immunosuppression are detailed.

Causative Organisms of Brain Abscess

A diverse range of bacterial organisms, including streptococci (S. millerii) and Staphylococcus aureus, along with other organisms like enteric Gram-negative bacilli, Pseudomonas, and various anaerobes are detailed.

Clinical Features of Brain Abscess

Common clinical descriptions associated with a space-occupying lesion, including headache, vomiting, drowsiness, confusion, seizures, and focal neurological signs.
Treatment varies depending on the abscess location but commonly involves surgical drainage alongside antibiotic therapies.

Summary

Categorization of acute bacterial, chronic/subacute meningitis, encephalitis, and brain abscess.
Diagnosis approaches including CSF examination (full report, Gram stain, AFB stain, India ink, culture, ABST), blood culture, bacterial antigen detection, PCR, and serological testing (blood and CSF) are listed.

Studying That Suits You

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Description

Test your knowledge on the types, sources, and treatments of meningitis. This quiz covers critical aspects of meningitis, including prevention strategies and specific guidelines for different populations. Perfect for students in health sciences or medical fields seeking to deepen their understanding of meningitis management.