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CP - JL > CNS Infections > Flashcards

CNS Infections Flashcards

1
Q

What is a brain abscess

A

A focal suppurative process within the brain parenchyma

Pus in the brain substance

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2
Q

What are the causes of a brain abscess

A

Often polymicrobial
Strep miller most common then staph aureus
Anaerobes, TB, toxoplasma gondii, gram -ve bacteria (e.coli and pseudomonas)

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3
Q

4 ways that brain abscesses develop

A

Direct spread from suppurative focus - middle ear, teeth, sinus
Haematogenous spread from distant focus - endocarditis or bronchiectasis (multiple abscesses)
Trauma
Cryptogenic - no focus

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4
Q

What is a common cause of abscess after trauma/surgery

A

Staph aureues

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5
Q

Presentation of a brain abscess

A

Headache, focal neurological deficit, fever, consuion, dizziness/seizures, neck stiffness

Papilloedema and coma are a late sign

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6
Q

What is a subdural empyema

A

In-between the dura and arachnoid mater

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7
Q

What causes subdural empyemas

A

Often polymicrobial

Aerogic gram -ve, strep penuomia, staph auresus, haemophilius

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8
Q

Where do subdural empyemas usually spread from

A

Sinuses (50-80%)

Or middle ear and mastoid (10-20%)

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9
Q

How do subdural empyemas present

A 
Headaches
Fever
Neurological focal deficit
Confusion
Seizure
Coma
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10
Q

How do we treat subdural empyema

A

Drainage of pus and culture to guide antibiotic therapy

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11
Q

What are complications of brain abscesses

A

Raised intracranial pressure - causes mass effect, coning

Rupture - into ventricles - causes ventriculitis - may result in death!!!!

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12
Q

How do we manage bran abcsesses

A

Drain them
Reduces the ICP, confirms the diagnosis, gets pus for investigations, examine antibiotics efficiency, avoid spread to ventricles - CAN BE FATAL

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13
Q

Why do we need specific antibiotics to treat brain abscesses

A

The distinct properties of the BBB and blood-CSF barrier means that only certain drugs can penetrate the CSF and brain

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14
Q

What drugs are good for penetrating pus

A

Ceftazidime (good for pseudomonas), metronidazole, ampicillin, penicillin, cefuroxime, cefataxime

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15
Q

How do we treat sinugenic/odontogenic abscesses

A

Ceftazidime (2-6 hrs), metronidazole (8 hrly)

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16
Q

How do we treat otogenic abscesses

A

benzyl penicillin, Ceftazidime (2-6 hrs), metronidazole (8 hrly)

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17
Q

How long do we treat drained abscesses for

A

4-6 weeks, oral switch may be an option

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18
Q

What is meningitis

A

Inflammation of the meninges

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19
Q

What is encephalitis

A

Inflammation of the brain

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20
Q

What is menino-encephalitis

A

Inflammation of the brain and meninges

Usually difficult to distibuish between encephalitis and meningitis

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21
Q

What is Aseptic meningitis

A

Clinical picture of meningitis
White cell count >5x10^5/L in CSF - may be higher in children
Negative bacterial culture in CSF
Viruses are the most common cause!

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22
Q

What is a virus capsid

A

Protein coat made up of capsomeres (subunits)

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23
Q

Where do some viruses derive their envelopes

A

From the host cell membrane

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24
Q

What is the most common type of meningitis

A

Viral meningitis

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25
Who is meningitis most common in
Neonates and age 5
26
What are the most common causes of viral meningitis
Enteroviruses Then HSV2 Also echovirus, coxsachie virus, parecho, polio Good to determine their travel history
27
How does viral meningitis cause disease
Colonisation of mucosal surface Invasion of the epithlieum Disseminates and CNS invasion Symptoms mainly due to the inflammatory response in the CNS
28
How can viral meningitis disseminate and invade the CNS
Via the cerebral microvascular endothelial cells Via the choroid plexus epithelim Spreads along the olfactory nerve
29
Presentation of viral meningitis
Fever Meningeal symptoms (fever, neck stiffness, photophobia) Someimtes viral prodrome - lethargy, myalgias, arthralgias, sore throat, D&V) Also Kerning's and Brudzinski's sign
30
How might viral meningitis present in children
Meningeal symptoms may be absent | Look for nuchal rigidity and bulging anterior fontanelle
31
What is Kerning's skin
Hip and knee flexed 90 degrees to the body Cant extend knee due to pain/stiffness in the hamstrings Spinal cord can't stretch due to inflamed menignes
32
What is Brudzunkis sign
Lying down - flexing the neck causes the hips and knees to flex Occurs because the spinal cord can't stretch due to the inflamed meninges
33
What investigations do we do for meningitis
FBC, U&E, CRP, Clotting, blood culture (renal function often decreases) CT of the head Lumbar puncture
34
Why do we do CT of the head in menigitis
To look for evidence of raised ICP and look for a differential diagnosis
35
What do we ook for in lumbar puncture
Microscopy, culture, sensitivity Protein Glucose - do ration against blood Viral PCR try and do lumbar puncture within 1 hour
36
CSF findings in viral meninfits
White cell count pleocytosis (WBCs in the CSF) Lymphocytic Predominance of neutrophils in first 24 hours Normal level of protein Glucose ratio normal or low
37
What is the normal glucose ratio
50-66% | Normally there is less glucose in the CSF than in the plasma
38
What are other microbiology tests we can do for meningitis
Throat swab/stool sample for enteroviruses | Serology - for Mumps, EBV/CMV, HIV and other virses (travel indicated)
39
Treatment of viral meningitis
Start IV antibiotics e.g. cefotaxime if any risk of bacterial meningitis No evidence for use of specific treatment Supportive therapy NOTIFIABLE DISEASE for prophylaxis
40
When does enteroviral meningitis commonly occur
Late summer/early autumn
41
Symptoms of enteroviral meningitis
Fever, vomiting, anorexia, rash, URT symptoms
42
Treatment of enteroviral meningitis
No specific treatment | Full recovery expected
43
What does HSV1 cause
Cold sores and viral encephalitis
44
What does HSV2 cause
VIral meningitis and genital herpes
45
2nd most common cause of viral meningitis
HSV2 - following primary infection or occur during/between relapses
46
Treatment of HSV2 meningitis
No evidence that acyclovir is effective
47
What is Mollarets meningitis
Recurring aseptic meningitis
48
Can VZV cause meningitis
Rare cause but can occur during chickenpox or shingle s(look for rash) or occur on its own, or after vaccination
49
How to treat VZV
No evidence acyclovir helps But can help for the rash Complete recovery normal
50
Does mumps lead to meningitis
In 10-30% of people meningitis occurs 5 days after the onset of parotitis
51
Symptoms of mumps related viral meningitis
5 days after the onset of parotitis Abdominal pain Orchitis
52
Treatment of mumps meningitis
No specific treatment Full recovery normal Preventable with vaccine
53
When can meningitis occur with HIV
Part of primary infection Associated features of fever, lymphadenopathy, pharyngitis and rash Symptoms are self-limiting
54
Main cause of viral encephalitis
HSV1 causes 90% of viral encephalitis cases
55
Presentation of viral encephalitis
Main difference to meningitis is the altered mental state and low GCS Fever, headache and meningism (may be absent) Also get focal neurologies! - seizures, weakness, dysphasia/aphasia, cranial nerve palsy, ataxia
56
What investigations do we do in viral encephalitis
Bloods, CT, MRI, Lumbar, EEG Findings generally the same as viral meningitis (low glucose, high protein)
57
What changes are typically seen in viral encephalitis
Upton 75% show abnormal temporal lobe activithy
58
How to treat viral encephalitis
High dose IV aciclovir 14-21 days - start on clinical suspicion Oral switch not recommended
59
Epidemiology of viral encephalitis
Rare but high mortality if untreated! Bimodal incidence - under 20 years and over 50 years most affected Equally spread between sexes
60
HSE Pathogenesis
Primary infection vs reactivationn Direct transmission of the virus along neural/olfactory pathways! Reactivation in the trigeminal ganglia
61
Where can HSE reactivate
In the trigeminal ganglia
62
Mortality of HSE
Upto 70% Poor prognosis if GCS les than 6 Survivors frequently have neurological problems, paralysis, speech loss and personality chagne
63
What is acute disseminated encephalomyelopathy (ADEM)
Immune mediated CNS demyeliination
64
What precedes ADEM
Viral infection or vaccination
65
Clinical features of ADEM
Same as encephalitis - but the PCR for the virus will all be negative. Look for autoantibodies in the blood
66
How do we treat ADEM
Steroids/other immunosuppressants recovery is variable
67
Who does japanese encephalitis often affect
Children
68
When can you get japanese encephalitis
Dog, fox, bat bites
69
What is the mortality of japanese encephalitis
100%
70
What is a common cause of encephalitis in the immunosuppressed
Toxoplasma gondii
71
When do we get toxoplasma gondii
From cat faeces and undercooked meat
72
What type of bacteria is neisseria meningitidis
Gram -ve diplocooci | Needs blood to grow
73
Natural habitat of neisseria meningitidis
Nasopharynx 5-10% of people are carriers
74
What increaeses before neisseria meningitidis
Increase in group A strep carriage before epidemics | Also increased rate in the first term of uni
75
Where does neisseria meningitidis replicate
Crosses the BBB and replicates in the sub arachnoid space
76
Presentation of neisseria meningitidis
Fulminant septicaemia - may get purpuric rash Meningitis if it crosses the BBB an get pyogenic meningitis without rash
77
How do we treat bacteria meningitis
Cephalosporins then penicillin Chemoprophylaxis for neisseria and meningitis - rifampicin and ciprofloxacin Steroids for strep pneumonia only
78
What groups of neisseria meningitidis do we have vaccines against
Groups A + C and W135 not B Group A usually causes the massive epidemics
79
What type of bacteria is haemophilia influenza
Gram -ve cocci | Needs blood to grow
80
What type of haemophilia influenza causes meningitis
Type b - encapsulated | But 25-80% of the other types are non capsulated
81
What type of haemphilius influenza do we have a vaccine against
Type b
82
What type of bacteria is strep pneumonia
Gram +ve cocci Needs blood for growth Normal habitat the respiratory tract - transmission via droplet
83
How do we test for strep pneumonia
Optochin test - it is sensitive to the optochin antibiotic
84
What age groups do each of the bacterial meningitis affect
Neisseria - neonates and teens Haemophilia - 2 months to 2 years Strep pneumonia - all ages
85
Normal CSF results
Cell Count
86
Bacterial CSF Results
Cell Count >200 Cell Type Polymorphs Glucose
87
Viral CSF Results
Cell Count 20-200 Cell Type Lymphocytes Glucose Normal or reduced Protein Normal or increased
88
TB CSF Results
Cell Count 20 -200 Cell Type Lymphocytes Glucose Reduced Protein Increased
89
Cryptococcus CSF results
Cell Count 20 -200 Cell Type Lymphocytes Glucose Normal or reduced Protein Incresed
90
What usually cause neonatal menngitis
Beta haemolytic streptococci E. coli Listeria
91
Treatment of neonatal meningitis
Cephalosporins, ampicillin, gentamicin
92
What is the most common form of meningitis
Lymphocytic/ Viral Due to enteroviruses or HSV2 Just symptomatic treatment
93
What happens in TB meningitis
Insidious onset
94
How do we treat TB meningitis
Steroids
95
What makes you more at risk of TB meningitis
Immunocompromised Alcholic From endemic area
96
Meningitis complications
Death, sepsis, raised ICP | Deafness, delayed development, seizures, shakes, hydrocephalus
97
Where is clostridium tetani usually found
Widespread in the soil -
98
How does clostridium tetanus cause a disease
Non-invasive but produces a toxin | Toxin binds to ganglionic receptors preventing the release of inhibitor interneurons
99
What symptoms do you get with clostridium tetani
Lockjaw - tonic muscle spasms, opinthons Resp difficulties CV instbility Sympathetic nervous system problems
100
Treatment of tetanus
Anti-toxin Penicillin or metranidaole Drugs for muscle spasms/relaxtants
101
What is cryptococus
A yeat
102
Describe cryptococcal meningitis infection
Insidious onset | Often get respiratory illness first
103
How do we see cryptococcal infection histologically
Yeast seen in CSF with Indian Ink Stain
104
How do we treat cryptococcus
Prolonger amphotericion, flucytosine or fluconazole
105
What type of meningitis has a higher mortality
bacterial
106
How do we look for bacterial meningitis
Gram staining | Shows intracellular gram -ove cocci
107
How does neisseria meningitides cause disease
Able to modify inflammatory processes
108
What are other complications of neisseria menigitidis
Chronic meningococcal bacteraemia with arthralgia Focal sepsis Conjunctivitis and endopthalmitis
109
How many types of haemophilius influenza are there
6 | It is part of the normal flora
110
What is strep pneumonia often resistant to
Penicillin resistant
111
Is there a vaccine for strep pneumonia
Conjugate vaccine available against common serotypes
112
Other causes of lymphocytic meningitis
Spirochete - treponemal, borrelia
113
How do we diagnose viral encephalitis
Diagnosis by detectingg viral nucleic acid in the CSF
114
What test do we do for tB
Ziehl Neelson
115
Why is TB diagnosis difficult
Difficutl to grow AFB
116
How do we diagnose brain abscesses
Need a scan to confirm
117
How does the tetanus toxin spread
Via bloodstream and retrograde transport

CP - JL (14 decks)

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