lecture 7 - meningitis Flashcards
What is meningitis?
A disease that results in swelling of the meninges and increased inter cranial pressure
Which types of pathogens can cause meningitis?
bacteria, viruses, fungi
What is the time frame of a chronic CNS infection?
> 4 weeks
What is encephalitis?
Inflammation of the brain due to an infection or allergic reaction
What are the key causes of non-infectious meningitis?
Lymphoma/leukaemia, subarachnoid haemorrhage, drug reactions, autoimmunity
What is meningoencephalitis?
Inflammation of the brain and meninges
What is the most common route of infection for infectious meningitis?
Haematogenous - via the bloodstream
What is the most common route of infection in meningitis?
haematogenous
What is the term for the presence of bacteria in the blood?
Bacteraemia
What is the term for the presence of viruses in the blood?
viraemia
What is the term for the presence of fungi in the blood?
fungaemia
What are the 4 possible routes of infection in the development of infectious meningitis?
Haematogenous spread, direct innoculation, contiguous spread, PNS->CNS
How does direct inoculation cause infectious meningitis?
Trauma, surgery, procedures can all allow pathogens to enter the brain
How does contiguous spread of infection cause meningitis?
Local infections, usually in the head, can spread to the meninges/brain
What type of pathogen typically causes infections spread via nerves from the PNS to CNS?
viruses
Are the meninges sterile or unsterile in health?
Sterile
What are the 3 layers of the meninges (outer to inner)?
Dura mater, arachnoid mater, pia mater
Which layer of the meninges contains CSF?
Arachnoid mater - central layer
What are the 3 classifications of infectious meningitis?
Acute, aseptic, chronic
What type of meningitis is pyogenic?
Acute bacterial meningitis
What immune cell can be found in large quantities in the CSF in acute bacterial meningitis?
neutrophils
What is the key characteristic of bacterial culture in aseptic meningits?
Negative for bacteria - indicating a viral aetiology
What cell type is found in large amounts in the CSF in cases of aseptic/viral meningitis?
Large numbers of lymphocytes
What types of bacteria typically cause chronic meningitis?
Tuberculosis, syphilis
What cell type is found in large amounts in the CSF in cases of chronic meningitis?
Lymphocytes
Which pathogen cause of meningitis has the lowest morbidity/mortality and is typically self-limiting?
Viruses (aseptic meningitis)
What are the key respiratory commensal bacteria that cause meningitis?
neisseria meningitidis, strep. pneumoniae, haemophilus influenzae
Which types of virus are associated with aseptic meningitis?
Enteroviruses, herpes, mumps, measles, influenza
What disease is associated with increased risk of cryptococcus fungal meningitis?
HIV/AIDS (immunodeficiency increases susceptibility)
Why are neonates vulnerable to meningitis?
They have an immature immune system
What is the most common cause of bacterial meningitis in NZ?
Neisseria meningitidis
What are the signs/symptoms of acute bacterial meningitis?
Fever, neck stiffness, photophobia, lethargy, myalgia, arthralgia, headache, seizures, mottles skin, rash, cold extremities
What is the “classic triad” in meningitis?
A trio of common symptoms: fever, neck stiffness, headache
What is the most common symptom of meningitis?
Fever
What are the symptoms of acute bacterial meningitis in infants?
Lethargy, irritability, poor feeding, high pitched cry, bulging fontanelle
What can bulging fontanelle be a sign of in infants?
Bacterial meningitis
What is the process that causes the rash characteristic of bacterial meningitis?
The haemorrhage of capillaries under the skin leading to spots of redness/bruising
Which bacteria typically causes a hemorrhagic rash in cases of meningitis?
N. meningitidis
What is the name for the rash spots in early stage meningitis?
Petechiae
What is the type of rash found in late stage meningitis?
Purpuric
What is the key clinical sign of a meningitis rash?
Non-blanching (in cup test)
What test is commonly used to identify meningitis rashes?
Cup/tumbler test - check for non-blanching rash
What 2 signs are commonly used to assess lower limb presentations of meningitis?
Kernig’s sign, Brudzinski’s sign
What is Kernig’s sign in meningitis?
Knee cannot be fully extended when hip flexed 90 degrees
What is Brudzinski’s sign in meningitis?
Passive flexion of the neck causes flexion of both legs and thighs
What are the prodromal symptoms of meningitis?
nausea, vomiting, fatigue, malaise, lethargy, cough, pharyngitis, headache, myalgia
What are the complications of meningitis?
Death, amputation, hearing loss, blindness, epilepsy, cerebral palsy, cognitive issues
What are the at risk groups for meningitis?
infants, elderly, students, immunosuppressed, trauma, surgery, asplenia, bacteraemia
Is Neisseria meningitidis gram positive or negative?
negative
How is Neisseria meningitidis transmitted?
Respiratory aerosol
How is meningitis diagnosed?
Lumbar puncture for CSF then gram stain/culture/PCR to determine pathogen
What is the normal appearance of CSF in lumbar puncture?
Clear, colourless
What is the typical appearance of CSF from lumbar puncture in cases of meningitis?
turbid, yellow/orange/green from blood, green from pus
What are the characteristic WBC, glucose and protein levels in CSF in bacterial meningitis?
High neutrophils, low glucose, high protein
What are the characteristic WBC, glucose and protein levels in CSF in viral/aseptic meningitis?
High lymphocytes, normal glucose, high protein
What technique can be used to identify meningitis causing viruses in CSF?
PCR
What is the empiric antibiotic given for suspected/unclassified meningitis?
Ceftriaxone
What is the role of steroids in meningitis treatment?
Reduce inflammation to decrease risk of complications
What vaccine is part of the vaccine schedule for infants (Child vax programme) and at risk groups?
Meningococcal B
