26 Bacterial and fungal meningitis Flashcards
What are the CSF findings in bacterial meningitis?
Very high polymorph count.
i.e. mainly neutrophils, also basophils + eosinophils
What is the main cause of bacterial meningitis?
Where is carriage, and what %?
Neisseria meningitidis.
Nasopharynx. Below 20% are carriers, but increased above 20% amongst smokers and before outbreak.
How does N meningitidis survive intravascularly?
Capsule protects against complement based attack.
Acquires iron from transferrin.
What does N meningitidis usually cause alongside meningitis?
Fulminant septicaemia ± purpuric rash.
What is the treatment for N meningitidis meningitis?
Ceftriaxone, cefotaxime, penicillin.
What is the prophylaxis and vaccination for N meningitidis?
Rifampicin + ciprofloxacin.
Active against Group A+C+W135.
Which other bacteria cause meningitis besides N.meningitidis? (2)
Haemophilia influenzae (type b is most invasive, most are non-capsulate). Streptococcus pneumoniae (most are capsulate).
Who gets meningitis caused by haemophilus influenzae?
Infants.
What are the virulence factors that H influenzae has? (3)
Type b capsule.
Fimbriae.
IgA proteases.
What is the treatment for H influenzae meningitis? (3)
Ceftriaxone, cefotaxime, ampicillin.
β-lactamase producing strains common
Which meningitis causing organism is identifiable by the optochin test?
Streptococcus pneumoniae.
Who gets meningitis caused by Streptococcus pneumoniae?
Elderly.
Immunocompromised.
Which type bacterial cause of meningitis has no chemoprophylaxis available?
Streptococcus pneumoniae.
Why are steroids used in meningitis? (2)
How do they alter antibacterial Rx?
Strep pneumoniae pathology partly due to immune system.
Dexamethasone decreases mortality.
If vancomycin used add rifampicin as dexamethasone decreases vanc levels in CSF.
What are the causative organisms of neonatal bacterial meningitis? (3)
Group B haemolytic Streptococci.
Escherichia coli.
Listeria monocytogenes.
