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Neurology > Microbiology > Flashcards

Microbiology Flashcards

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1
Q

What is meningitis

A

Inflammation of the meninges

all layers

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2
Q

What can an untreated CNS infection lead to

A

Brain herniation - death

Cord compression and necrosis - leads to paralysis

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3
Q

Location of a brain infection determines the symptoms - true or false

A

TRUE

Depends where in the brain is affected and what it is responsible for

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4
Q

What is encephalitis

A

Infection of the whole brain

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5
Q

How does pyogenic meningitis appear

A

Pus forming - get a thick suppurative layer on the brain

Would see lots of neuropils microscopically and in LP

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6
Q

What are the classifications of meningitis

A

Acute pyogenic - bacterial
Acute aseptic - viral
Acute focal suppurative infection - abscess or empyema
Chronic bacterial infection 0 TB

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7
Q

What is the treatment for bacterial meningitis

A

Ceftriaxone IV
Must give steroids with the antibiotics - dexamethasone
For the over 60s or the immunocompromised you must add in amoxicillin to cover for listeria

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8
Q

What is the most common organism that causes bacterial meningitis

A

Strep pneumo

Listeria also common in the elderly or immunocompromised

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9
Q

If a patient with meningitis has recently travelled to a country with high penicillin resistance, what should be included in their treatment

A

Vancomycin

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10
Q

How do you diagnose viral meningitis

A

Viral stool culture
Throat swab
CSF PCR

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11
Q

How do you treat viral meningitis

A

Treat symptomatically – anti-emetic, rehydration etc

Usually self limiting so treat supportively

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12
Q

What are the clinical features of encephalitis

A 
Confusion, change in mental state 
May have neck stiffness or other 'meningitis' symptoms 
Stupor or coma 
Seizures
Partial paralysis 
Speech and memory symptosm
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13
Q

Encephalitis has a fast onset - true or false

A

False

Usually insidious - takes a few days to a week

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14
Q

What investigations would you do for encephalitis

A

LP
EEG
Blood cultures
CT/MRI -will see changes

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15
Q

What viral cause of encephalitis must you rule out before treating with antibiotics

A

Herpes simplex

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16
Q

Do you get MRI changes in meningitis

A

NO

You do with encephalitis - differentiates between them

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17
Q

What are the common signs and symptoms of bacterial meningitis

A 
Fever 
Cold peripheries 
Vomiting 
Drowsiness and lethargy
Confusion and irritability 
Non- blanching rash 
Severe muscle pain and headache 
Stiff neck 
Photophobia 
Convulsions and seizures
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18
Q

What are the risk factors for bacterial meningitis

A

Immunosuppression - listeria risk
Neurosurgery or head trauma - staph risk
Fracture of the cribriform plate - strep pneumo

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19
Q

Which organism is the most common cause of bacterial meningitis in neonates

A

Listeria
This is why pregnant ladies shouldn’t eat certain cheeses etc
Also strep pneumo

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20
Q

Which organism is the most common cause of bacterial meningitis in children

A

Haem influenza

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21
Q

Which organism is the most common cause of bacterial meningitis in teenagers and young adults

A

Neisseria meningitidis

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22
Q

Which organism is the most common cause of bacterial meningitis in adults

A

Strep pneumoniae

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23
Q

Which organism is the most common cause of bacterial meningitis in the elderly

A

Strep pneumoniae and listeria

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24
Q

What are some of the lifelong consequences of a meningitis

A 
Limb loss 
Deafness 
Mental impairment 
Blindness 
Cerebral palsy

These will affect around 25% of those who survive meningitis

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25
Which cranial nerves are vulnerable to damage in meningitis
III and VI | If pus collects around them they can be damaged
26
Describe the pathogenesis of bacterial meningitis
The bugs can come from nasopharyngeal colonization They can travel from sinusitis, mastoiditis or across skull fracture to reach the brain Remote focal infections can also track up to the brain - pneumonia etc
27
Which bacteria can cause meningitis in the immunocompromised population
The typical agents - strep and staph - can still affect Listeria TB Cryptococcus is seen in HIV with a low CD4+
28
What treatment is required for Cryptococcus meningitis
Seen in HIV patients Give IV Amphotericin B/Flucytosine and fluconazole Creates a very high pressure in CSF so must do regular daily LPs to relieve pressure
29
Where is Neisseria meningitides usually found
Found in the throats of healthy carriers
30
How does neisseira meningitides reach the brain
Probably gain access to the meninges through the bloodstream. The bacteria may be found in leukocytes in CSF
31
What causes the effect in meningococcal meningitis
The endotoxin released by Neisseria meningitides
32
Where is H influenza usually found
It is part of normal throat microbiota
33
What does H influenza need in order to grow
Blood factors | Therefore need to be cultured on chocolate agar
34
Where is strep pneumoniae usually found
The nasopharynx
35
Who is most susceptible to strep pneumonia meningitis
Hospitalized patients, patients with CSF skull fractures, diabetics/ alcoholics and young children May be linked to CNS implants like cochlear Some occur secondary to pneumonia
36
Which group will struggle to fight off encapsulated organisms
Those without a spleen | Puts them at higher risk
37
The pneumococcal vaccine also protects against meningitis - true or false
True
38
What antibiotic is needed to treat listeria
IV ampicillin or amoxicillin
39
What type of bacteria is listeria
Gram positive bacilli
40
What are the signs of TB meningitis
Usually a reactivation of the infection in the elderly Will have been non-specifically ill for weeks May have had previous Tb in CXR
41
How do you treat TB meningitis
Isoniazid and rifampicin are the key ones | Also add pyrazinamide and ethambutol
42
What investigations would you do for suspected meningitis
Bloods - cultures, FBC, U&E< LF, PCR, serology Throat swab - culture LP - unless signs of sepsis Can move onto viral PCR if that is the likely cause
43
What tests can be done on a CSF sample in suspected meningitis
Haematology - cell count and differential Microbiology - gram stain (done immediately) and cultures (takes several days) Chemistry - glucose and protein
44
How will glucose change in the CSF of someone with meningitis
It will be lower than usual | This is because the bacteria present will consume glucose
45
All bacterial meningitis will gave a positive culture - true or false
FALSE around 10-15% are culture negative Also even short duration of treatment can turn samples negative (e.g. if LP was delayed but antibiotics were started)
46
Which viruses commonly cause meningitis
Enterovirus - in autumn/summer and associated with GI symptoms HSV1 and 2 - will have cold sores In immunocompromised can be EBV or CMV
47
Describe the CSF findings in a viral meningitis
Predominantly lymphocytes Negative gram stain Normal protein (may be slight increase) Normal glucose
48
Describe the CSF findings in a bacterial meningitis
Predominantly polymorphs Positive gram stain High protein Lower glucose - less than 70% of BG
49
Describe the CSF findings in a tuberculosis meningitis
Predominantly polymorphs Positive or negative gram stain Very high protein Lower glucose - less than 60% of BG
50
What is aseptic meningitis
Means a non-pyogenic bacterial meningitis - doesn't produce pus Will have normal glucose and protein and less WBC
51
What are the indications for hospital admission in suspected menigitis
Signs of meningeal irritation An impaired conscious level A petechial rash Febrile or unwell and have had a recent fit Any illness, especially headache in those who have come into close contacts with meningococcal infection
52
What is the immediate management of suspected meningitis on admission
Take blood for culture and coagulation screen Start empirical treatment Take throat swab Disrupt and swab any skin lesions
53
When should you do a CT before an LP
``` Immunocompromised History of CNS disease New onset seizure Papilloedema - or other signs of raised ICP Abnormal level of consciousness Focal neurological deficit ```
54
What are the indications for LP
ALL adults with suspected meningitis require one | UNLESS there is a clear contraindication or there's a confident clinical diagnosis
55
Antibiotics should be started immediately, before investigations have come back (e.g. LP) - true or false
In suspected meningitis it is TRUE
56
Why are steroids given in meningitis
It reduced unfavourable outcomes and mortality | Give alongside the doses of antibiotics
57
When would you not give steroids in meningitis
Post-surgical meningitis, severe immunocompromise, meningococcal or septic shock or those hypersensitive to steroids
58
How can you prevent secondary cases of meningitis
Report all clinically suspected cases to public health ASAP GPs can contact close contacts to allow implementation of prophylaxis Label those at risk as higher risk persists for 6 months
59
What prophylaxis is available for those who have been in contact with
600mg rifampicin every 12 hours for 4 doses Lower dose for young kids - 10mg/kg OR 500mg ciprofloxacin single dose in adults
60
What vaccines are available for meningitis
Neisseria meningitidis - groups A,C,W,Y H. influenza - HiB Strep pneumo - pneumococcal vaccine
61
What is a normal protein ratio in CSF
<0.4
62
What is a normal glucose ratio in CSF
> 0.6 glucose (CSF:blood), | Usually around 60-70% of blood glucose
63
What are the normal CSF white and red cell counts
No red cells and no more than 5 white cells per mm3
64
What does normal CSF look like
Clear and colourless with no blood or neutrophils
65
What is meant by a blanching rash
Disappears when pressure is applied
66
Is it safe to do an LP in a patient without a CT first
Nope Need to look for signs of raised ICP, focal deficits or seizure If CT is abnormal or symptoms present then not safe due to herniation risk
67
How do Neisseria meningitidis appear on staining
Gram-negative diplococci
68
What prophylaxis is given to those who come into contact with meningitis
Ciprofloxacin
69
How can you treat HSV encephalitis
IV aciclovir
70
How do you treat encephalitis
IV Ceftriaxone and dexamethasone Amoxicillin for listeria cover Acyclovir if HSV risk
71
Middle ear infections can lead to encephalitis - true or false
True | Recurrent infections increase risk as it can spread to brain
72
Which organisms can cause brain abscesses
- strep pneumoniae - Bacteroides - staph

Neurology (18 decks)

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