meningitis Flashcards
(28 cards)
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
how is diagnosis made?
- Diagnosis based on:
– History & Examination
– Blood tests - FBC, blood films, CRP, blood culture, serology & PCR
- Microbiological testing of CSF sample – GOLD STANDARD
diagnostic test for meningitis
– Nasopharyngeal (throat) swab normally taken
through the mouth
what is CSF sample?
- Lumbar puncture drains cerebrospinal fluid from the back below the level of termination of the spinal cord
when should CSF not be taken?
– features of raised intracranial pressure (ICP)
– haemodynamic instability
– clotting abnormalities or thrombocytopenia
when may bacteria not be cultured from CSF sample?
after antibiotuc
what is the rational behind giving certain broad spec antibiotics?
– Antibiotic choice dependent on most likely causative organisms
– Determined by age
– Good CSF penetration essential
* Antibiotic can be changed if necessary once
causative organism has been identified
what should be done with empirical treatment?
– Patients with suspected meningitis should be
transferred to hospital – 999!
– Parenteral antibiotics administered in children as soon
as IMD is suspected (if practical)
* Benzylpenicillin (NICE guideline)
* Benzylpenicillin or cefotaxime (SIGN guideline)
– Transfer to hospital essential should not be delayed
– Treatment should not be delayed pending
investigations
– Benzylpenicillin withheld in allergy only due to
anaphylaxis
what is parenteral 3rd gen?
Parenteral 3
rd generation cephalosporin
monotherapy is appropriate first line
treatment in children over 3 months old.
– ceftriaxone (NICE guideline)
– cefotaxime (SIGN guideline)
what are supportive therapies that can be given?
- Corticosteroids
- Intravenous fluids
- Enteral nutrition
- Anticonvulsant therapy if appropriate
- Management of complications of septicaemia and
shock
– Respiratory support
– Correction of metabolic disturbances
– Intravenous fluids
– Vasoactive therapies
– Renal replacement therapies if required
what are the long term conplications of meningitis?
- Hearing loss
- Orthopaedic complications
- Skin complications
- Psychosocial problems
- Neurological and developmental problems
- Renal failure.
