Meningitis Flashcards

1
Q

What is meningitis

A

inflammation of the meninges

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2
Q

how does bacteria reach the meninges

A

through bloodstream

direct contact between the meninges and either nasal cavity or the skin

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3
Q

how does meningitis lead to cerebral oedema?

A

blood brain barrier becomes more permeable - vasogenic cerebral oedema (fluid leaks from blood vessels)
white blood cells enter CSF leading to interstitial oedema (fluid between cells)
walls of blood vessels become inflamed, leads to decreased blood flow and cytotoxic oedema

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4
Q

what are the 5 types of meningitis

A
acute pyogenic (bacterial) meningitis 
acute aseptic (viral) meningitis
acute focal suppurative infection (brain abscess, subdural and extradural empyema)
Chronic bacterial infection (TB)
acute encephalitis
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5
Q

What pathological features are seen in pyogenic meningitis

A

suppurative exudate covers leptomeninges

exudate in basal and convexity surfaces

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6
Q

what are the complications of meningitis

A

arachnoiditis - impacts on CSF absorption
Hydrocephalus and ventriculitis - communicating + non communicating
death
abscess formation
cerebral oedema
exudate can form around nerves (3+6)

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7
Q

what are the common causative organisms of pyogenic meningitis

A

neisseria meningitidis - gram negative bacterium
haemophilus influenzae - gram negative cornebacterium
streptococcus pneumoniae - gram posistive bacilli
listeria monocytogenes

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8
Q

what are the most likely causative organisms based on age group? (pyogenic meningitis)

A

neonates - listeria, streptococcus agalachie
children - h.influenzae
ages 10-21 - neisseria meningitidis
age over 21 - strep pneumoniae > neisseria meningitidis
over 65 - strep pneumoniae > listeria

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9
Q

which bacteria commonly affects students?

A

neisseria meningitidis

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10
Q

who are the three risk groups of listeria monocytogenes?

A

elderly, neonates, pregnancy

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11
Q

what are some common risk factors and their associated causative organisms? (pyogenic meningitis)

A

DECREASED CELL MEDIATED IMMUNITY: LISTERIA MONOCYTOGENES
NEUROSURGERY/ HEAD TRAUMA: STAPHYLOCOCCUS, GRAM NEGATIVE BACILLI
FRACTURE OF THE CRIBIFORM PLATE: STREPTOCOCCUS PNEUMONIAE

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12
Q

clinical features of pyogenic meningitis

A

fever, stiff neck, alteration in consciousness, headache, vomiting, pyrexia, photophobia, lethargy, confusion, petechial or purpuric rash, seizures,

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13
Q

neurological features of meningitis

A

focal neurological deficit, abnromal eye movement, facial palsy, balance problems/hearing impairment

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14
Q

clinical features of infants with meningitis

A

hypothermia, irritability, lethargy, poor feeding, apnoea, bulging fontanelle. high pitched cry

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15
Q

what are your first line investigations in meningitis?

A
CT
lumbar puncture (CSF analysis)
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16
Q

what other investigations could you consider in meningitis?

A

blood cultures, throat swab, blood EDTA for PCR

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17
Q

management of pyogenic meningitis

A

Ceftriaxone 2g bd + Dexamethasone

add ampicillin/amoxicillin if listeria suspected, or aciclovir if encephalitis

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18
Q

what are the indications for hospital admission?

A

signs of meningeal irritation, an impaired conscious level, 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

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19
Q

what are the common prophylactic regimes of pyogenic meningitis?

A

600 mg rifampicin orally 12-hourly for four doses (adults and children over 12 years), 10 mg/kg orally 12-hourly for four doses (aged 3-11 months) (IV).
500 mg ciprofloxacin orally as a single dose for adults and children aged more than 12 years (IV)
250 mg ceftriaxone intramuscularly as a single dose in adults, 125 mg iv as a single dose in children under 12 years

20
Q

What is the management of penicillin allergic pyogenic meningitis?

A

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.

21
Q

when should you give steroids in the management of pyogenic meningitis?

A

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)
do not give in post-surgical meningitis, severe immunocompromise, meningococcal or septic shock or those hypersensitive to steroids

22
Q

What is an causative organism of cryptococcal meningitis?

A

cryotococcus neoformo=us

23
Q

risk factor for cryptococcal meningitis

24
Q

management of cryptococcal meningitis

A

IV amphotericin B/flucytosine

Fluconazole

25
clinical features of cryptococcal meningitis
subtle neurological presentation disseminated infection aseptic CSF
26
what does aseptic meningitis mean?
non-pyogenic bacterial meningitis
27
general features of CSF of aseptic meningitis
low WBC, minimally elevated protei normal glucose
28
What are the common causes of viral meningitis
``` human enteroviruses - 5 subgernera coxsackieviruses echoviruses polioviruses herpes viruses - HSV1 (encephalitis), HSV2 (meningitis) arboviruses ```
29
risk factors of viral meningitis
``` exposure to mosquito or tick vector unvaccinated for mumps use of swimming pools and ponds immunosuppression exposure to rodents ```
30
clinical features of viral meningitis
headache, nausea and vomiting, photophobia, neck stiffness, fever, rask, kernigs sign, brudzinskis sign
31
investigations for viral meningitis
viral stool culture, throat swab, CSF PCR
32
treatment for viral meningitis
self limiting, supportive | aciclovir only if herpes
33
What are 2 types of brain abscesses?
single or multiple
34
pathological features of single abscesses
occur adjacent to source
35
pathological features of multiple abscesses
haematogenous spread
36
causes of single abscesses
``` local extension (e.g. mastoiditis) direct implantation of infectious agent (skull fracture) ```
37
causes of multiple abscesses
bronchopneumonia, bacterial endocarditis
38
risk factors for development of abscesses
sinus and dental infections, penetrating trauma, pulmonary infections, congenital heart disease, HIV, transplantation, neutropenia
39
symptoms of a brain abscess
fever, ICP | symptoms of underlying cause
40
investigations for a brain abscess
CT or MRI | Aspiration for culture
41
management of brain abscess
Aspiration and antibiotics
42
CSF features of bacterial meningitis
``` Appearance - cloudy Pressure - raised WBC - 500-10000 neutrophils Glucose - decreased Protein - >150 ```
43
CSF features of viral meningitis
``` Appearance - clear Pressure - normal WBC - 10-100 lymphocytes Glucose - normal Protein - raised ```
44
CSF features of fungal meningitis
``` Appearance - clear/cloudy Pressure - normal WBC - 10-500 mononuclear cells Glucose - decreased Protein - >1000 ```
45
CSF features of TB meningitis
``` Appearance - opaque Pressure - rasied WBC - 50-500 neutrophils/monocytes Glucose - decreased Protein - >100 ```
46
CSF of crytococcal meningitis
``` Appearance - clear Pressure - raised WBC - 100-200 lymphocytes Glucose - decreased Protein - 50-200 ```