meningitis Flashcards
what is menngitis?
Defined as inflammation of the membranes
covering the brain and spinal cord (meninges)
what causes meningitis?
Caused by a wide variety of micro-organisms
– Viruses
– Bacteria
– Fungi
when is a person at increased risk of meningitis?
Increased risk following head trauma and in
the presence of ventriculo-peritoneal shunts
what is the most common cause of bacterial meningitis
Neisseria meningitidis
how many serogroups are there of neisseria? how are they characterised?
– Thirteen types (serogroups)
* Characterised by surface structures in the capsule and outer cell membrane
* Five responsible for the majority of cases of invasive disease in humans
* A, B, C, Y and W-135
what are other bacterial pathogens that cause meningitis?
– S. Pneumoniae
* gram positive cocci
– H. influenzae type B
* gram negative rods
what are other causes of meningitis?
- Viral
– Less severe than bacterial meningitis; usually resolves without tx.
– Caused by viruses that live in the intestines - Enteroviruses (most commonly)
- Mumps and measles viruses and herpes viruses
– Poor hygiene may increase the risk of transmission.
– Not all people exposed to the virus will develop meningitis - Fungal
– Life threatening; rare disease
– Usually presents in patients with compromised immune function
– Slow progression, difficult to diagnose and treat
– Cryptococcus, Candida - Non infective
– Complication of head injury, brain surgery, some cancers
– Drugs may be implicated
where are the highest rates of meningitis?
across sub-saharan Africa
how is neisseria meningitidis transmitted?
– normal inhabitant of the human nasopharynx
– transmitted by droplets/ secretions from the
upper respiratory tract
– spread between individuals with close contact
– epidemics occur in crowded environments
* Other organisms: infections of the skin,
urinary tract, GI tract, etc may be transmitted
via the bloodstream
what are the risk factors for meningitis?
- Infants and young children
- Community settings
– Increased close contact - Asplenia
- People with compromised immune system
- People exposed to active or passive tobacco smoke.
- Elderly
- Pregnancy and working with animals increases the
risk of developing meningitis associated with Listeria
bacteria
how may meningococcal present?
- Bacterial meningitis (15%)
- Meningococcal septicaemia (25%)
- Combination of both (60%)
what are the classic symptoms?
– Fever
– Headache
– Photophobia
– Neck stiffness
– Petechial rash
how does it present in young children?
- Fever
- Vomiting, nausea and poor feeding
- Irritability, drowsiness, confusion
- Sudden onset of fever and rigors
- Muscle and joint aches
- Cold extremeties
- Symptoms of raised ICP
- Bulging fontanelle
Irregular breathing, abnormal tone - Petechial rash
- Usually associated with N meningitidis
what is a petechial rash?
- Usually present in septicaemia
but may be absent or scant in meningitis - Rash may be blanching and maculopapular in
early disease but develops into petechial, non
blanching rash. - Rapidly evolving petechial rash is a sign of
severe disease - Non blanching rash – MEDICAL EMERGENCY!
what is Kernig’s and Brudzinski’s sign in
meningitis?
severe neck stiffness causes a patient’s hips and knees to flex when the neck is flexed.
Severe stiffness of the hamstrings causes an
inability to straighten the leg when the hip is
flexed to 90 degrees
