Central Nervous System Infections Lecture Flashcards
Viral meningitis - time of year, viruses, diagnosis, treatment
COMMON
Late summer/autumn
Viruses - Enteroviruses eg ECHO or other microbes and non infectious causes
Diagnosis - viral stool culture, throat swab and CSF PCR
Treatment - supportive as self limiting
Viral encephalitis - viruses
Herpes simplex - diagnose QUICKLY
Is Viral Encephalitis travel or occupational related?
Yes.
Travel - West Nile, Japanese B encephalitis, Tick Borne Encephalitis
Occupation - Rabies
Clinical Features Encephalitis (6)
Insidious onset - sometimes sudden Meningismus Stupor, coma Seizures, partial paralysis Confusion, psychosis Speech, memory problems
Investigations for Encephalitis (3)
LP
EEG
MRI
if delay start pre-emptive aciclovir as prompt therapy improves outcomes
Describe MRI findings in Encephalitis
Inflamed portion of the brain brightest white. Usually temporal lobe
Common causes of bacterial meningitis in.. Neonates Children 10 to 21 21 onward Elderly
Neonates - listeria, group b strep, e.coli Children - h.influenze 10 to 21 - meningococcal 21 onward - pneumococcal>meningococcal Elderly - pneumococcal > listeria
Common causes of bacterial meningitis with these risk factors... Decreased CMI S/P neurosurgery or opened head trauma Fracture of the cribiform plate Immunocompromised
Decreased CMI - listeria
S/P neurosurgery or opened head trauma - staphylococcus, gram negative rods
Fracture of the cribiform plate - pneumococcal
Immunocompromised - s.pneumonia, n.meningitidis, listeria
Bacterial Meningitis - Clinical Signs (3)
Fever
Stiff neck
Alteration in consciousness
Bacterial Meningitis - Signs and Symptoms (8)
Headache Vomiting Pyrexia Neck stiffness Photophobia Lethargy Confusion Rash
Signs of bacterial meningitis often absent or atypical in..? (3)
The very young
The very old
Immunocompromised people
In bacterial meningitis which kind of WBC would you expect to find in the subarachnoid fluid?
Neutrophils
Describe some potential pathogenesises of bacterial meningitis (3)
- Nasopharyngeal colonisation
- Direct extension of bacteria
- parameningeal foci (sinusitis, brain abscess, mastoiditis)
- across skull defects/fracture - From remote foci of infection eg endocarditis, pneumonia, UTI
Antibiotic of choice for listeria monocytogenes
IV Ampicillin/amoxicillin
Gram positive bacilli
Intrinsically resistant to ceftriaxone
Which subgroup of patients do we mainly see crytococcal meningitis in?
HIV patients
When we send CSF for interpretation what do we want to know from…
- Haematology
- Microbiology
- Chemistry
- cell count, differential
- gram stain, cultures
- glucose, protein
What is the typical cell type CSF findings in Viral meningitis
cells are lymphocytes
What are the CSF findings for bacterial meningitis
- Cell type
- Protein levels
- Glucose levels
- predominantly polymorphs
- protein high
- glucose less than 70% of blood glucose
What is the CSF findings for partially treated bacterial meningitis
- Cell type
- Protein levels
- Glucose levels
- predominantly lymphocytes
- protein high or very high
- glucose normal or decreased
CSF predictive of bacterial meningitis with 99% accuracy if….
WBC count >2000
Neutrophils >1180
Protein >220mg/dl
Glucose
What is aseptic meningitis?
Non pyogenic bacterial meningitis
What spinal fluid formula does aseptic meningitis typically have?
Low WBC
Minimally elevated protein
Normal glucose
Infectious and treatable causes of aseptic meningitis/encephalitis syndrome (9)
HSV 1 and 2 Syphilis Listeria (occasionally) Tuberculosis Cryptococcus Leptospirosis Cerebral malaria African tick typhus Lyme disease
Non-infectious and treatable causes of aseptic meningitis/encephalitis syndrome (6)
Carcinomatous Sarcoidosis Vasculitis Dural venous sinus thrombosis Migraine Drug Co-trimoxazole IVIG NSAIDS
Indications for hospital admission in acute adult bacterial meningitis (5)
- signs of meningeal irritation
- an impaired conscious level
- a petechial rash
- who are febrile or unwell and have had a recent fit
- Any illness, especially headache, and are close contacts of patients with meningococcal infection, even if they have received a prophylactic antibiotic
Early inpatient action for acute adult bacterial meningitis (4)
- take blood for culture and coagulation screen
- give the empirical treatment - LP
- take a throat swab which should be plated as soon as practicable by the microbiologist
- disrupt and swab or aspirate any petechial or purpuric skin lesions for microscopy and culture
What should be done to investigate patients with papilloedema or focal neurological signs?
Urgent CT or nuclear magnetic resonance scan
BUT DONT delay appropriate antibiotics
Who should undergo CT before Lumbar Punctures? (6)
Immunocompromised patients History of CNS disease New onset seizure Papilloedema Abnormal level of consciousness Focal neurologic deficit
Indications for lumbar puncture in acute adult bacterial meningitis
All adult patients with suspected meningitis except when a clear contraindication exists (III) or of there is a confident clinical diagnosis of meningococcal infection with a typical meningococcal rash (III)
Should antibiotics be given before or after lumbar puncture in acute bacterial meningitis?
BEFORE
Should you give steroids if you are not confident you are using the correct antimicrobials?
NO
What is the empiric antibiotic therapy for acute adult bacterial meningitis?
EMPIRIC ANTIBIOTIC THERAPY
IV CEFTRIAXONE 2g bd
ADD IV AMPICILLIN/AMOXICILLIN 2g qds IF LISTERIA SUSPECTED
What is the empiric antibiotic therapy for acute adult bacterial meningitis IF penicillin allergy?
PENICILLIN ALLERGY (RASH OR ANAPHYLAXIS)
If there is a clear history of anaphylaxis to beta-lactams give chloramphenicol iv 25 mg/kg 6-hourly with vancomycin iv 500 mg 6-hourly or 1g 12-hourly.
If listeria suspected and penicillin allergy co-trimoxazole alone has been used successfully for this infection.
When do we give steroids to patients suspected of bacterial meningitis?
Give to all patients suspected of bacterial meningitis (10mg iv 15-20 min before or with the first dose of antibiotic and then every 6 hours for 4d)
Unfavourable outcome reduced from 25% to 15% and mortality from 15 to 7%
Most striking benefit in pneumococcal meningitis
Less likely also to have impaired consciousness,seizures and cardio-respiratory failure
Do not give in post-surgical meningitis, severe immunocompromise, meningococcal or septic shock or those hypersensitive to sterroids
