CNS Infection Flashcards
(33 cards)
What is septicaemia
Meningococcal bacteria multiply and produce poisions which attack blood vessel walls causing blood to Leak out
What is meningitis
Meningococcal bacteria cross from blood into lining of brain
Viral meningitis
Often caused by Human enteroviruses Herpes 2 virus Mumps and measles Arboviruses
Fungal meningitis
Very rare but serious
Usally effects immunocomprimised
Bacterial meningitis
Serious , life threading condition
Most. Commonly effects extremes of age
Most common causes bacteria such as streptococcus pneumoniae and neisseria meningitidis
Major causes in neonates include E. coli
Gram negative enteric bacteria contribute to less than 10% casss
Neisseria meningitidis intro
Aerobic , gram negative diplococcus
Has a polysaccharide capsule which helps pathogenic strains revisit phagocytosis and lysis
Classified into serogroupsm
Most common = A,B,C W135 and Y
men A
Rare in uk. Causes large epidemic in sub sarharan Africa countries , Middle East and Indian sub content
MenB
~70% meningococcal causes In Europe and > 80% uk
MenC
Now rare. Usally occurs in ‘clusters’ in uk.
MenW135
Uncommon in uk. Usually associated with travellers returning from hajj pilgrimages to a Mecca in Saudi Arabia
MenY
Very rare in uk. Common in North America
Prevelance on neisseria men
Marked seasonal variation
Occurs at any age
Children <9 most at risk , peak incidence <1 year
Smaller secondary peak 15-19
Overall decline over last two years
gp sees average 1-2 over career
Transmission of n.men
~ 10% carry it in nasopharynx, usually without Ill effects
Penetrate mucosal cells and enter bloodstream in less than 1%. Crosses BBB and causes meningitis in 50%
Transmitted via droplets or secretions from URT
Transmission requires frequent or prolonged contact
Incubation period = 2-7 days
Risk factors of meningitis
Young age Winter season Absent or non functioning spleen Older age >65 Immunicomprimised state Incomplete immunisation Cancer Organ dysfunction Smoking Overcrowding Sickle cell disease
Pathophysiology of men
Colonisation of nasopharyngeal and invasion of sub mucosa by overcoming host defences - physical barriers ,m local immunity , phagocytes/ macrophages
Invasion of blood stream
Meningeal invasion via Bbb
bacterial replication In CSF
host inflammatory responses
Pus and abscess formation
Common , non specific symptoms
Fever Vomiting /Naseua Lethargy Irritability / unsettles behaviour Ill appearance Refusing food/drink Muscle ache /joint pain Difficulty breathing /respiratory symptoms
Less common, non specific symptoms
Chills / shivering
Diarrhoea
Abdominal pain/distension
Sore throat or other ENT symptoms
Neurological symptoms
Bulging fontanelle Stiff neck or back p Altered mental state Photophobia Kernings sign
Circulatory symptoms
Non blanching Rash Limb pain Cold hands or feet Unusual skin colour Capillary refill time >2s Shock and hypotension
What is the rash called
Petechial/ purpuric rash
Complications 30-50% survivors
Neurological - eg hearing loss, seizures, cognitive impairment , motor deficits, visual impairments
Physical- eg amputations ,skin scars
Reduced quality of life
Anxiety
Les ring difficulties
Emotional and behavioural issues
Diagnosis
Confirmed In secondary care Physical examination Monitoring of vital signs blood tests for CRP and WBC Lumbar puncture with examination of CSF
Appearance of CSF
Turdy, cloudy
Management overview
Urgent antibiotic treatment - based on clinical situation and most probable bacteria aetiology .further treatment depends on bacteria found in CSF
Antibiotic drug properties needed to achieve therapeutic conc of antibiotic in CSF- look at lipid solubility , ionic dissociation at blood pH, low mw
Adjunctive therapy eg corticosteroids
Supportive therapy - restore and maintain respiratory, cardiac and neurological function
