CNS Infections Flashcards by Caroline Maguire

What may untreated infection cause?

Brain herniation and death

* Cord compression and necrosis, with subsequent permanent paralysis

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What is meant by the term ‘aseptic’? What may it be?

The bacterial cultures are negative

May be virus

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What is acute encephalitis an infection of?

Brain parenchymal

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What does pyogenic meningitis show?

A thick layer of suppurative exudate, covering the leptomeninges over the surface of the brain

i.e this is bacterial meningitis

Basically, pus in the subarachnoid space

Leptomeninges - only the arachnoid and pia

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Where is exudate found in pyogenic meningitis?

In the basal and convexity surface

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Microscopically, what is seen in pyogenic meningitis?

Neutrophils in the subarachnoid space

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Is viral meningitis common?

YES

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At what time of year does viral meningitis become an issue?

Late summer - Autumn

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Suggest causes of viral meningitis.

ENTEROVIRUSES like ECHO virus
(will have bit of a flu, photophobia)
But also other microbes and non-infectious causes

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How is the diagnosis of viral meningitis made?

Viral stool culture
Throat swab
CSF PCR

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What is the treatment of viral meningitis?

Supportive

usually self limiting

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What investigation should be done in suspected encephalitis?

MRI

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What questions particularly helps differentiate between meningitis and encephalitis? Explain

Is there any altered behaviour or cognition, personality change or altered consciousness?

** Encephalitis tends to present more with changes in behaviour, compared to meningitis.

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What are the clinical features of encephalitis?

Insidious onset, although sometimes sudden.
Meningismus (a triad of headache, photophobia and nuchal rigidity)
Stupor, coma.
Seizures, partial paralysis.
Confusion, psychosis.
Speech, memory symptoms

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What is meningismus?

A triad of headache, photophobia and nuchal rigidity (back of neck stiffness)

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What investigations should always be carried out?

Lumbar puncture
EEG
MRI

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What should be done if Ix’s are delayed?

Start pre-emptive acyclovir as prompt therapy improves outcomes (death)

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List the most common signs + symptoms of meningitis.

Fever + Cold
Vomiting
Drowsiness
Muscle pain
Headache
Photophobia
Confusion
Stiff neck
Rash
Convulsions/seizures

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What organism usually causes CAM in neonates?

Listeria
Group B strep
E. coli

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What organism usually causes CAM in children?

H. influenza

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What organism usually causes CAM in ages 10-21?

Neisseria meningitidis (freshers)

think ‘N’ for notty lol

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What organism usually causes CAM aged over 21?

Streptococcus pneumoniae > Neisseria meningitidis

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What organism usually causes CAM in those over 65?

Streptococcus pneumoniae > Listeria

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What bacteria is decreased cell mediated immunity most often associated with

Listeria monocytogenes

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What bacteria is neurosurgery/head trauma most often associated with?

Staphylococcus, Gram negative bacilli

What bacteria is fracture of the cribriform plate associated with?

Streptococcus pneumoniae | think in nose  travels to brain through # in cribriform plate

What is the 'alcohol triad'?

Strep pneumoniae endocarditis, bacterial pneumonia, meningitis (think pneumonia if lying on ground drunk)

Where are clusters found?

At the base of the brain

What nerves are especially vulnerable when there is an infection?

CN’s III and VI

What prevents meningitis becoming an abscess?

Pia

What can brain abscesses cause?

Secondary ventriculitis, and hence meningitis

Name 3 sources/ways that bacterial meningitis can develop.

1. Nasopharyngeal colonization 2. Direct extension of bacteria -parameningeal foci (sinusitis, mastoiditis, brain abscess) OR across skull defects/fracture 3. From remote foci of infection (ie. endocarditis, pneumonia, UTI)

Listeria monocytogenase likes?

FRIDGES

TB meningitis is

'slow and grumbling'

What does neisseria meningitis cause?

Meningococcal meningitis

Where is neisseria meningitis found?

In the throats of healthy carriers | think reason why vaccination is given just before uni

How does bacteria gain access to the meninges?

Via the blood

Where may bacteria be found?

In leukocytes in the CSF

What are the symptoms of meningitis due to?

ENDOTOXIN

H. influenza is part of the normal what?

Throat microbiota

What does H. influenza require for growth?

Blood

What is the most common cause of meningitis in children under 4?

H. influenza type B

Where is S. pneumonia commonly found?

Nasopharynx

Who is most susceptible to S. pneumonia meningitis?

Hospital pts. Pts with CSF skull fractures. Diabetics/alcoholics. Young children

Describe listeria monocytogenes?

gram +ve bacilli

Who is most susceptible to listeria monocytogenes?

Neonates. >55y/o’s. Immunosuppressed patients, especially in the context of malignancy

What is the best antibiotics for mistrial monocytogenes?

IV Ampicillin/Amoxicillin

What does someone with TB meningitis have?

TB on CXR

The CSF yield in TB meningitis is weak. What should therefore be done?

PCR and culture are important here due to the poor yield from CSF

How is TB meningitis treated?

Isoniazid + Rifampicin (add pyrazinamide + ethambutol

What type of infection is Cryptococcal Meningitis?

FUNGAL

What people get cryptococcal meningitis?

People with HIV

What kind of infection is cryptococcal meningitis?

Disseminated

How does cryptococcal meningitis appear on CSF?

Aseptic

How is cryptococcal meningitis treated?

With IV amphotericin B/flucytosine. | Fluconazole

What bloods should be done in someone with suspected meningitis?

* FBC * Urea, creatinine, electrolytes * LFT's * Clotting screen * Procalcitonin * PCR * Serology * Glucose

What are the clinical signs of bacterial meningitis?

Fever Stiff neck Altered level of consciousness

List signs + symptoms of bacterial meningitis.

* Headache * Vomiting * Pyrexia * Neck stiffness * Photophobia * Lethargy * Confusion * Rash

When should you be cautious about doing a lumbar puncture?

If raised ICP

What position should be utilised while doing a lumbar puncture?

Sitting

If flow of CSF in a lumbar puncture is fast, what should you measure?

Opening pressure

Describe H. influenza.

Gram -ve rods

Describe S pneumonia.

Gram +ve diplococci

Describe N. meningiditis.

Gram -ve diplococci

In partially treated bacterial meningitis, what may predominate? What, however, allows this to be differentiated from viral meningitis?

Lymphocytes may predominate. | - but the protein is often high

Neutrophilic Pleocytosis + Low CSF Glucose can sometimes mean?

Bacterial meningitis

What is aseptic meningitis?

Non-pyogenic bacterial meningitis

Describe the spinal fluid in aseptic meningitis?

* A low number of WBC. * A minimally elevated protein. * A normal glucose

What are the indications for hospital admission?

* Signs of meningeal irritation. * An impaired conscious level. * A petechial rash. * Pt is febrile or unwell, and has 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

What type of swab should be taken in someone with suspected meningitis?

Throat

What should be done to petechial or purpuric skin rashes?

Disrupt and swab or aspirate

Who should get a CT before doing a lumbar puncture?

* Immunocompromised * History of CNS disease * New onset seizure * Papilloedema * Focal neurological deficit * Altered level of consciousness

What are the key WARNING SIGNS to look for in someone with bacterial meningitis?

* Marked depressive 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 are the indications for lumbar puncture in early inpatient management? What should be done before LP?

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)

Outline the standard management of a patient with bacterial meningitis. State what is done in penicillin allergy.

IV Ceftriaxone 2g bd. * ADD IV Ampicillin/Amoxicillin 2g qds IF LISTERIA IS SUSPECTED.

What is given in penicillin allergy (rash or anaphylaxis)?

Chloramphenicol IV (25mg/kg 6-hourly) with Vancomycin IV (500mg 6-houtly or 1g 12-hourly)  if clear hx of anaphylaxis to beta-lactams. Co-trimoxazole alone  if Listeria suspected and allergic to penicillin.

Who should steroids be given to?

ALL patients with suspected bacterial meningitis

When should steroids be given?

10mg iv 15-20 min before or with the first dose of antibiotic and then every 6 hours for 4d

When should steroids NEVER be given?

Post-surgical meningitis. Severe immunocompromise. Meningococcal or septic shock. Steroid hypersensitivity

Outline option 1 of prophylaxis regimens.

Adults + Children >12yrs: Rifampicin (600mg, 12-hourly for 4 doses). Ages 3-11: Rifampicin (10mg/kg orally, 12 hourly for 4 doses). JUST REMEMBER RIFAMPICIN

When Rifampicin is given, what should the patient be warned of?

* Reduced efficacy of oral contraceptives. * Red colouration of urine. * Staining of contact lenses

Outline option 2 of prophylaxis regimens.

Adults + Children >12yrs: Ciprofloxacin (500mg orally as single dose). - use of ciprofloxacin in younger children is NOT recommended

Outline option 3 of prophylaxis regimens.

Adults: Ceftriaxone (250mg IM as single dose). Children <12y/o: Ceftriaxone (125mg IV as single dose). CEFTRIAXONE

Outline option 4 of prophylaxis regimens.

Vaccines

What should be noted when taking an LP from someone with meningitis?

* Cell count * Glucose * Protein * RBC's

What cell type would be high in an LP from a patient with viral meningitis?

Neutrophils (polymorphs)

What cell type would be high in an LP from a patient with bacterial meningitis?

Lymphocytes

What are examples of what you should look for when trying to figure out the route by which someone has got viral meningitis?

Ear infection Sinusitis Laceration to face/head

What symptoms should ALERT you that someone has meningitis

* Crescendo headaches * Nausea * Fever * Slowness

What is Kernig sign? What should you worry about?

Neck Stiffness | - Meningitis

When is imaging mandate in meningitis?

If focal neurological signs or papilloedema

CNS Infections Flashcards

(91 cards)