Infections of the CNS Flashcards
Infection of the membranes around the brain
Meningitis
Meninges
Subarachoroid space
Encephalitis
Infection of the substance of the brain
Brain abscesses
Localised lesion within the brain
3 most common causes of bacterial meningitis
Steptococcus pneumoniae
Neisseria meningitidis
Haemophilus influenzae
Causes of viral meningitis
ECHO
Coxsackie
Herpes simplex
Causes of bacterial meningitis
- Cryptococcus neoformans
- Mycobacterium tuberculosis
- Naegleria fowleri
- Coagulase negative staphylococci
- Treponema pallidum
Neonatal meningitis
Symptoms often not obvious
Group B streptococci may be found in the female genital tract - increased infection in premature babies or protracted labour
If these is contracted in the first week of life mortality is 60%
After one week mortality is 20%
Treatment with penicillin or gentamycin
Mothers carrying this are treated with benzylpenicillin
Can be due to listeria monocytogenes = gram positive bacilli
Can cause septicaemia
Streptococcus pneumoniae meningitis
Gram positive diplococci and is encapsulated Often in children less than 2 years old High mortality associated with it 20-30% Lanceolate Sore throat and photophobia Gentamycin and ampicillin
Neisseria meningitidis
Gram negative dipococcus Associated with polynuclear leukocytes (neutrophils) Oxidase positive Needs 5-10% CO2 to grow Intracellular 20% carry this in the oropharynx Encapsulated and the ABC W5 Y C has decreased Petichial skin rash Skin of septicaemia Rifampicin used to treat
Haemophilus influenzae
Pleomorphic gram negative bacteria Encapsulated Pathogen of the respiratory tract 3-4 months to 3-4 years Fastidious X and V Pittman B type
Mycobacterium tuberculosis
Rare and fast onset It DOES NOT gram stain Grows very slowly in the lab Fever Severe headache Neck stiffness Photophobia
Diagnosis
Lumbar puncture to obtain CSF
Macroscopic examination for turbidity and bloodstaining
Microscopy for total and differential count
Microscopy for gram or india ink stain
Bacterial meningitis - high protein, low glucose, turbid
TB is opalescent
Treatment of streptococcal meningitis
Unknown - empirical treatment based
Healthy child - cefotaxine
Cefotaxine used for streptococcus pneumoniae but for those resistant vancomycin is used
Treatment of meningococcal meningitis
Penicillin or cephalosporin treatment of choice for meningococcal meningitis can be used in combination with cholamphenicol
Treatment of haemophilus influenza meningitis
Haemophilus influenzae usually produces b-lactamases so cefotaxine is used
Rifampicin has been used to treat those that come into contact with it
Treatment for Mycobacterium tuberculosis
Isoniazid and rifampicin
Vaccines
2013 vaccine belonging to belonging to group B
Hib vaccine for infants 2,3 and 4 year olds
Brain abscess
Focal supprative lesion in the brain parenchyma
Cause of brain abscess
Often occur after surgery
May be due to osteomyelitis or ear infection
Usually polymicrobial with anaerobic bacteria
Staph aureus is the most common
Contigious suppurative focus
Haemotogous spread
After trauma
Crytogenic
Lumbar puncture and brain abscesses
Can be fatal
Can lead to raised intracranial pressire
Rare causes of brain abscesses
Actinomycetes Nocardia M Tb T. pallidum B. burgoferi Aspergillus
Symptoms of a brain abscess
Fever Headache Focal neurological deficit Nausea Vomiting Papilloedemia
Treatment of brain abscesses
Drainage and antibiotics
Gram negative and Ziehl Neelson stain
Benzylpenicillin, metronidazole and cefotaxine
Subdural empyema
Infection enclosed between outer meningeal layers (dura and arachoid layers)
Polymicrobial
Anaerobes
Infection usually spread from the sinus
Headache, fever, confusion, seizure and coma
Drainage and antimicrobials
Ventriculoperitoneal shunt
Devices that are used to release high intracranial pressure caused by hydrocephalus
How does a ventriculoperitoneal stunt work?
Plastic deura leads fluid from a ventricle of the brain through a one way to the peritoneal cavity
Cause of ventriculoperitoneal stunt infection
Coagulase negative staphylococci by biofilm infection
Replaced the shunt
