Infections of the Nervous System Flashcards
Untreated infection may cause
-Brain herniation and death -Cord compression and necrosis with subsequent permanent paralysis
What are the different types of meningitis?
- acute pyogenic (bacterial) - acute aseptic (viral) - acute focal suppurative infection (brain abscess, subdural and extradural empyema) - chronic bacterial infection (tuberculosis)
What is acute encephalitis?
Infection of the brain parenchyma
Describe macroscopic pyogenic meningitis
Thick layer of suppurative exudate covers the leptomeninges over the surface of the brain. Exudate in basal and convexity surface
Describe microscopic pyogenic meningitis
Neutrophils in subarachnoid space
What are the common organisms causing bacterial meningitis - community acquired
pneumococcus
meningococcus
haemophilus influenzae
occasionally other gram -ve
Listeria
What is the treatment for bacterial meningitis - community acquired
Ceftriaxone IV 2g bd
(penicillin allergy: chloramphenicol IV 25mg/kg qds)
+
Dexamethasome IV 10mg qds
(3ml of 3.3mg/ml dexamethasome base injection)
What is the treatment for CA bacterial meningitis if listeria cover is needed?
If listeria cover required add;
Amoxicillin IV 2g 4 hourly to ceftriaxone & dexamethasone
(penicillin allergy: co-trimoxazole IV 120mg/kg divided into 4 doses/day)
What is the treatment for bacterial CA meningitis if recent travel (within last 6 months) to country with high rates of penicillin resistant pneumococcus then add;
Vancomycin IV (aim for predose level 15-20mg/L) or Rifampicin IV/PO 600mg bd
Which countries have high rates of pneumococcal resistance?
- canada
- china
- croatia
- pakistan
- poland
- spain
- mexico
- italy
- USA
- greece
- turkey
What is the duration of treatment for bacterial CA meningitis if no organism is identified?
no organism identified: 10 days if patient has clinically recovered
What is the treatment duration for CA meningococcal bacterial meningitis
5 days ceftriaxone (if patient not recovered by 5 days extend course to 7 days initially and review) + stop dexamethasone
What is the treatment duration for CA pneumococcal bacterial meningitis
10 days ceftriaxone (if patient taking longer to respond extend course up to 14 days) + 4 days dexamethasone
What is the treatment duration for CA penicillin/cephalosporin resistant pneumococcal bacterial meningitis
14 days ceftriaxone + vancomyxin (vancomyxin monotherapy not recommended due to concerns re CSF penetration) + 4 days dexamethasone
What is the treatment duration for CA listeria bacterial meningitis
at least 21 days amoxicillin + stop dexamethasone
What is the treatment duration for CA haemophilus influenzae bacterial meningitis
10 days of ceftriaxone + stop dexamethasone
What is the treatment duration for CA gram negative bacterial meningitis
21 days of antibiotic regime agreed with ID/micro + stop dexamethasone
When is viral meningitis common?
Late summer/autumn
How is viral meningitis diagnosed?
Viral stool culture, throat swab, CSF PCR
What is the treatment for viral meningitis?
Supportive
If you suspect a patient has viral encephalitis what should be done?
Assess ABCD and check glucose (+/- involve ICU)
If no contraindication ot lumbar puncture then LP; if contraindication then urgent CT
What are the contraindications for LP
Significant brain shift/swelling
TIght basal cisterns
Alternative diagnosis made
What should be checked on the LP?
Opening pressure
CSF and serum glucose
CSF protein
2 x MC & S
Virology PCR
Lactate
consider paired oligoclonal bands
What should be done if the delay before LP results are pending is >6 hours
Start IV aciclovir
What should be done after urgent CT if contraindication to LP?
If CSF findings dont suffest encephalitis what should be done?
Repeat LP every 24-48 hrs
If HSV/VZV encephalitis confirmed then what should be done?
if immunocompromised or aged 3 months- 12 years: 21 days IV aciclovir
If not 14 days IV aciclovir
- Repeat LP*
- If still +ve then 7 days IV aciclovir*
What questions should be considered in a history assessing a patient with suspected encephalitis?
- Current or recent fibrile or influenza-like illness?
- Altered behaviour or cognition, personality change or altered consciousness?
- New onset seizures?
- Focal neurological symtpms?
- Rash? (VZ, roseola, enterovirus)
- Others in family, neighbourhood ill? (measles, mumps, influenza)
- Travel history (prophylaxis and exposure for malaria, arboviral encephalitis, rabies, trypanosomiasis)
- recent vaccination? (ADEM)
- contact with animals (rabies)
- contact with fresh water? (leptospirosis)
- exposure to mosquito or tick bites (arboviruses, lyme disease, tick-borne encephalitis)
- known immunocompromise
- HIV risk?
What are the clinical features of encephalitis?
- insidious onset; sometimes sudden
- meningismus
- stupor, coma
- seizures, partial paralysis
- confusion, psychosis
- speech, memory symptoms
What are the common signs + symptoms of meningitis and septicaemia?
- fever
- headache
- vomiting
- diarrhoea
- muscle pain
- stomach cramps
- fever with cold hands and feet
What are some common signs of meningitis?
- fever, cold hands and feet
- vomiting
- drowsy, difficult to wake
- confusion and irritability
- severe muscle pain
- pale, blotchy skin- spots/rash
- severe headache
- stiff neck
- dislike bright lights
- convulsions/seizures
What is the cause of CA bacterial meningitis in neonates?
Listeria, group B streptocicci, e. coli
What is the cause of CA bacterial meningitis in children?
H. influenza
What is the cause of CA bacterial meningitis in ages 10 to 21?
Neisseria meningitidis
What is the cause of CA bacterial meningitis in age over 21?
Streptococcus pneumoniae > neisseria meningitidis
What is the cause of CA bacterial meningitis in age >65?
Streptococcus pneumoniae > listeria
What is the most likely cause of CA bacterial meningitis in a patient with the following risk factors;
- Decreased cell mediated immunity?
- Neurosurgery/head trauma?
- Fracture of the cribiform plate?
- listeria monocytogenes
- staphylococcus, gram negative bacilli
- Streptococcus pneumoniae, h. influenza, beta haemolytic strep group A
What is the most likely cause of bacterial meningitis post head trauma or CSF shunt?
Head trauma: s. aureus, s. epidermidis, aerobic GNR
CSF shunt: s. epidermidis, s. aureus, aerobic GNR, propionibacterium acnes
What life altering affects may arise as a result of meningitis/septicaemia?
Limb loss, deafness, blindess, cerebral palsy, quadriplegia, severe mental impairment
What are some of the consequences of purulent bacterial meningitis?
Clusters at the base of the brain
Convexities of rolandic and sylvian sulci
Exudate around nerves (III, VI cranial nerves particularly vulnerable)
What are the consequences of invasion of bacterial meningitis?
Pia prevents meningitis becoming abscess
Abscesses can cause secondary ventriculitis and henxy meningitis
What are the complications of meningitis?
- purulence
- invasion
- cerebral oedema
- ventriculitis/hydrocephalus
Describe the pathogenesis of bacterial meningitis?
- nasopharyngeal colonisation
- direct extension of bacteria
* parameningeal foci (sinusitis, mastoiditis, or brain abscess)*
* across skull defects/fracture* - from remote foci of infection
* endocarditis, pneumonia, UTI*
what kind of causative agents of bacterial meningitis may be seen in patients with CD4 <100
Cryptococcus neoformans
How do n. meningitidis access the meninges?
through the bloodstream
What are the symptoms of meningococcal meningitis a result of?
Endotoxin
How are military recruits prevented from meningococcal meningitis
Vaccinated with purified capsular polysaccharide
What is the mortality rate of meningitis with septicaemia?
15%
There are ___ types of H.influenzae based on capsule differences
H. influenzae type _ is the most common cause of meningitis in children under _
There are six types of H.influenzae based on capsule differences
H. influenzae type b is the most common cause of meningitis in children under 4
How can haemophilus influenzae be prevented?
A conjugated vaccine directed against the capsular polysaccharide antigen is available
Who is most susceptible to s. pneumoniae menigitis?
Hospitalised patients, patients with CSF skull fractures, diabetics/alcoholics and young children are most susceptible to s. pneumonia meningitis
How can pneumococcal pneumonia be prevented?
New conjugate vaccine for pneumococcal pneumonia also provides protection against pneumococcal meningitis [in children]
Listerial monocytogenes;
Gram _____ _____ (_ blood cultures)
______ but on rise
Mainly _______ illness
_____ and > __ years or _________ especially malignancy
Antibiotics of choice;
__ ______/________
________ no value as intrinsically resistant
Listerial monocytogenes;
Gram positive bacilli (+ blood cultures)
Sporadic but on rise
Mainly bacteraemic illness
Neonatal and > 55 years or immuno-suppressed especially malignancy
Antibiotics of choice;
IV Ampicillin/Amoxicillin
Ceftriaxone no value as intrinsically resistant
Tuberculous mengitis;
_________ in elderly
High index of suspicion for ______
Often __-______ ill health
Previous __ on ___
Poor yield from ___
High ______ if not treated
_________ + ________ key (add ______+_______)
Tuberculous mengitis;
reactivation in elderly
High index of suspicion for diagnosis
Often non-specific ill health
Previous TB on CXR
Poor yield from CSF
High morbidity if not treated
Isoniazid + Ridampicin key (add pyrazinamide + ethambutol)
Cryptococcal meningitis;
______
Mainly in ____ disease
CD4<___
_______ infection
Subtle _______ presentation
_____ picture on CSF
Serum and CSF cryptococcal ______
IV _______ B/_______
_____le
Cryptococcal meningitis;
Fungal
Mainly in HIV disease
CD4<100
Disseminated infection
Subtle neurological presentation
Aseptic picture on CSF
Serum and CSF cryptococcal antigen
IV amphotericin B/flucytosine
fluconazole
Patient presents with suspected meningitis (and no signs of shock or severe sepsis)
Which Bloods should be done?
- blood cultures
- FBC, urea, creatinine, electrolytes, LFTs, clotting screen
- Procalcitonin (CRP if unavailbale)
- Meningococcal and pneumococcal PCR
- serology sample
- glucose
Patient presents with suspected meningitis and septicaemia
Which Bloods should be done?
blood cultures
FBC, urea, creatinine, electrolytes, LFTs, clotting screen
Procalcitonin (CRP if unavailbale)
Meningococcal and pneumococcal PCR
serology sample
glucose
Patient presents with suspected meningitis and septicaemia
Which tests should be done?
bloods
throat swab for bacterial culture
Patient presents with suspected meningitis and no signs of shock or severe sepsis
Which tests should be done?
bloods
throat swab
CSF
Further tests
Patient presents with suspected meningitis and no signs of shock or severe sepsis
Which CSF testing should be done?
- opening pressure
- microscopy, culture and sensitivity
- meningococcal and pneumococcal PCR
- protein
- glucose
- lactate
Patient presents with suspected meningitis and no signs of shock or severe sepsis
Which further tests should be done if no aetiology on first panel?
If bacterial meningitis seems likely ;
16S rRNA PCR on CSF
If viral meningitis seems likely ;
CSF PCR for: HSV 1, HSV 2, VZV and enterovirus
Stool for enterovirus PCR
throat swab for enterovirus PCR
CSF pleocytosis is not _______ ______
CSF pleocytosis is not bacterial meningitis
CSF interpretation
Tube 1. _______: ___ ____. differential
Tube 2. _______: g__ _____, c_____
Tube 2. _____: ______, _____
Tube 4: H______: C___ ______, _______
CSF interpretation
Tube 1. haematology: cell count. differential
Tube 2. Microbiology: gram stain, cultures
Tube 2. Chemistry: glucose, protein
Tube 4: Haematology: cell count, differential
__-__% of bacterial meningitides are _____ negative
10-15% of bacterial meningitides are culture negative
Which viruses suggest a patient is immunocompromised?
- EBV
- CMV
- HHV -6/7
- T. Gonfii
- JC virus
What are the typical CSF findings in acute viral meningitis?
Cells:
Gram stain for bacteria:
Bacterial antigen detection:
Protein g/l (normal 0.1-0.4):
Glucose mmol/l (normal 2.3-4.5):
Cells: 101-103 (lymphocytes)
Gram stain for bacteria: negative
Bacterial antigen detection: negative
Protein g/l (normal 0.1-0.4): normal or slightly high
Glucose mmol/l (normal 2.3-4.5): usually normal
What are the typical CSF findings in acute bacterial meningitis?
Cells:
Gram stain for bacteria:
Bacterial antigen detection:
Protein g/l (normal 0.1-0.4):
Glucose mmol/l (normal 2.3-4.5):
Cells: 101-104 (predominantly polymorphs)
Gram stain for bacteria: positive
Bacterial antigen detection: positive
Protein g/l (normal 0.1-0.4): high
Glucose mmol/l (normal 2.3-4.5): less than 70% of blood glucose
What are the typical CSF findings in acute tuberculous meningitis?
Cells:
Gram stain for bacteria:
Bacterial antigen detection:
Protein g/l (normal 0.1-0.4):
Glucose mmol/l (normal 2.3-4.5):
Cells: 101-103
Gram stain for bacteria: positive or negative
Bacterial antigen detection: negative
Protein g/l (normal 0.1-0.4): high or very high
Glucose mmol/l (normal 2.3-4.5): less than 60% of blood glucose
In partially treated bacterial meningitis __________ may predominate but the protein is often ___
In partially treated bacterial meningitis lymphocytes may predominate but the protein is often high
CSF is 99% predictive of bacterial meningitis if;
WBC count > ____
Neutrophils > ____
Protein > ___ mg/dl
Glucose < __ mg/dl
Glucose CSF/serum < ____
CSF is 99% predictive of bacterial meningitis if;
WBC count > 2,000
Neutrophils > 1180
Protein > 220 mg/dl
Glucose < 34 mg/dl
Glucose CSF/serum < 0.23
What are the other non-infectious causes of neutrophillic pleocytosis & low csf glucose?
- Chemical-meningitis (contrast)
- Bechet syndrome
- Drug induced (NSAIDs, sulfa, INH, IVIG, OKT3)
What is aseptic meningitis?
Term used to mean non-pyogenic bacterial meningitis
Aseptic meningitis describes a spinal fluid sample that typically has;
a __ number of WBC
a ______ _______ protein
A normal ______
Aseptic meningitis describes a spinal fluid sample that typically has;
a low number of WBC
a minimally elevated protein
A normal glucose
What are the treatable infectious causes of aseptic meningitis/encephalitis syndrome?
- HSV 1 & 2
- Syphilis
- Listeria (occasionally)
- Tuberculosis
- Ctyptococcus
- Leptospirosis
- Cerebral malaria
- african tick typhus
- lyme disease
What are the treatable non-infectious causes of aseptic meningitis?
- carcinomatous
- sarcoidosis
- vasculitis
- dural venous sinus thrombosis
- migraine
- drugs
- co-trimoxazole
- IVIG
- NSAIDs
What are the indications for hospital admission in acute adult bacterial meningitis?
- signs of meningeal irritation
- impaired conscious level
- a petechial rash
- febrile or unwell and have had a recent fit
- any illness, especially headache and and close contacts of patients with meningococcal infection- even if they have had prophylaxis
Providing a patient’s (with acute adult bacterial meningitis) airway, breathing and circulation do not require immediate attention what should be done on arrival in hospital?
- blood culture for coagulation screen
- give the treatment as outlined in ‘initial therapy before pathogens are identified’ vide infra, and immediately thereafter
- take a throat swab which should be plated as soon as practicable by the microbiologist
- disrupt and swab or aspirate any petechial or pupuric skin lesions for microscopy and culture
who should undergo CT prior to LP?
- immunocompromised state: HIV/AIDS, immunosuppressants, after transplantation
- History of CNS disease: mass lesion, stroke or focal infection
- New onset seizure: within 1 week of presentaiton
- Papilloedema: presence of venous pulsations suggests absence of high ICP
- Abnormal level of consciousness
- Focal neurological deficit: dilated nonreactive pupil, abnormalities of ocular motility, abnormal visual fields, gaze palsy, arm or leg drife
What are the warning signs in meningitis?
- marked depressed conscious level (GCS <12) or a fluctuating conscious level (fall in GCS >2)
- Focal neurology
- seizure before or at presentation
- shock
- bradycardia and hypertension
- papilloedema
What patients should and should not be given steroids in bacterial meningitis
ALL patients (10mg iv 15-20 min before or with first dose of antibiotic and then every 6 hours for 4d)
NOT; post-surgical meningitis, severe immunocompromise, meningococcal or septic shock or those hypersensitive to steroids
What are the key interventions in managing bacterial meningitis with low GCS or fluctuating GCS?
- admit to highly supervised clinical area; do baseline investigations
- secure airway and high flow O2
- IV 2G ceftriaxone stat [+/- amoxicillin if >55 to cover listeria]
- IV corticosteroids
- DO NOT wait for CT/LP
What are the contact prophylaxis regimens?
- 600mg rifampicin orally 12-hourly for four doses (adults and children over 12 years)
- 10ml/kg rifampicin orally 12-hourly for four doses (ages 3-11 months) (IV).
specific warnings about reduced efficacy of oral contraceptives, red colouration of urine and staining of contact lenses should be given
OR
- 500mg ciprofloxacin orally as a single dose for adults and children aged more than 12 years (not licensensed for this purpose but has been extensively used in school and community outbreaks). use of ciproflocaxin in younger adults is not recommended
OR
- 250mg ceftriaxone intramuscularly as a single dose in adults
-
125mg IV ceftriaxone as a single dose in children under 12 years.
*
What vaccines are available?
- neisseria meningitidis
- serogroups A and C (W135 & Y) - commonly used in travel vaccination
- group C conjugate vaccine
- haemophilus influenzae (HiB vaccine)
- Streptococcus pneumoniae
- pneumococcal vaccines- polysaccharide and conjugate
