2. Meningitis Flashcards
what is meningitis?
inflammation of meningeal lining of brain and spine
where is CSF found?
within the subarachnoid space, beneath the arachnoid membrane, on top of the pia mater. It also surrounds the spinal cord and fills open spaces (ventricles) inside the brain
function of CSF?
CSF helps to maintain a constant pressure inside the skull, known as intracranial pressure (ICP).
common bacterial causes of meningitis in adults?
Neisseria meningitidis
Haemophilus influenzae
Streptococcus pneumoniae
common viral causes of meningitis in adults?
Enteroviruses: Echoviruses Coxsackie viruses A and B poliovirus Herpes viruses: Herpes simplex virus 1 and 2
typical CSF in bacterial infection?
cloudy white cell count increased cell type = neutrophils proteins = increased glucose = low
typical CSF in viral infection?
clear white cell count increased cell type = lymphocytes proteins = moderate increased glucose = normal or slightly decreased
describe gram stain of neisseria meningitides
gram negative
diplococci
characteristics of neisseria meningitides?
- Normal flora of nasopharynx
* Spread via Inhalation of respiratory droplets
clinical significance of neisseria meningitides?
• Gram-negative Sepsis, meningitis, meningococcal sepsis
virulence factors of neisseria meningitides?
- LPS capsule = Antiphagocytic
* Pili – attaches to nasopharyngeal mucosa
investigations of neisseria meningitides?
- Gram stain of CSF from lumbar puncture
- Throat swab
- Tumbler test
treatment/ prevention of neisseria meningitides?
- Ceftriaxone (Passes through BBB)
- Cefotaxime – In new-born children
- ABCWY Vaccine
what type of antibiotic is ceftriaxone?
beta lactam - cephalosporin - inhibits cell wall synthesis
clinical features of meningitis?
• classic triad - fever - headache - neck stiffness • photophobia • phonophobia • vomiting • non-blanching rash
investigations of meningitis
FBC, U&E, lactate, CRP blood culture lumbar puncture PCR Tumbler test
what are two diagnostic tests for meningitis?
kernig’s sign - positive when the thigh is flexed at the hip and knee at 90 degree angles, and subsequent extension in the knee is painful
brudzinski’s sign - if flexing neck causes automatic flexion of knees
how are pathogens of meningitis spread?
direct spread - through skull fracture, up through nose
haemotogenous spread - blood
what is the tumbler test
placing tumbler glass over rash to see if it blanching or not
what is the rash found in meningitis?
petechial rash - tiny bleed into the skin - low platelet count
what is DIC?
The main mechanisms of DIC are inflammatory cytokine-initiated activation of tissue factor-dependent coagulation and insufficient control of anticoagulation pathways. At a simplistic level the coagulation process goes out of control. Lots of small clots form. These use up many of the anticoagulation factors. The consequence is that there is bleeding occurring at the same time as the small clots are being formed. As an example platelets (which are important in forming clots) are used up in making the clots and the platelet count becomes low. This allows for the small bleeds into the skin (petechiae).
what is seen in patients with severe DIC?
Ecchymoses: The petechial lesions can coalesce and form larger lesions that appear ecchymotic. Ecchymoses (diameter >10 mm) are mainly noted in patients with severe DIC. These lesions are secondary to subcutaneous hemorrhage.
