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Flashcards in CNS Infections Deck (77):
1

What can an untreated CNS infection cause?

Brain herniation and death
Cord compression and necrosis with subsequent permanent paralysis

2

What does the gross morphology of pyogenic (bacterial) meningitis show?

Thick layer of suppurative exudate covering the leptomeninges over the surface of the brain
Exudate in basal and convexity surface

3

What does pyogenic meningitis show microscopically?

Neutrophils in the SA space

4

What is the DDx for fever and altered mental status?

Encephalitis
Meningitis
Meningoencephalitis
Encephalomyelitis
Severe sepsis syndrome due to infection elsewhere

5

When does viral meningitis usually present?

Late summer/autumn

6

What causes viral meningitis?

Enteroviruses e.g. ECHO virus
Other microbes and non-infectious causes also

7

How is viral meningitis diagnosed?

Viral stool culture, throat swab and CSF PCR

8

What is the treatment for viral meningitis?

Supportive as self-limiting

9

What viruses can cause viral encephalitis?

HSV (serious)
VZV
CMV
HIV
Measles

10

What is the treatment of HSV encephalitis?

Aciclovir IV high doses- must be recognised, admitted and treated within 6 hours

11

What is the history and treatment of VZV encephalitis?

History of shingles
High dose acyclovir

12

What are the travel related causes of viral encephalitis?

West Nile, Japanese B encephalitis, Tick Borne encephalitis

13

What are the occupational related causes of viral encephalitis?

Rabies

14

What are the non-infectious causes of viral encephalitis?

Autoimmune etc

15

What are the clinical features of encephalitis?

Insidious onset-sometimes sudden
Meningismus
Stupor, coma
Seizures, partial paralysis
Confusion, psychosis
Speech, memory symptoms

16

What investigations are required in viral encephalitis?

LP
EEG
MRI

17

If there is a delay in investigations in suspected viral encephalitis what should be done?

Start pre-emptive acyclovir as prompt therapy improves outcome

18

What are the MRI findings in encephalitis?

Inflamed portion of the temporal lobe, involving the uncus and adjacent parahippocampa I gyrus (brightest white on MR)

19

What are the common causes of bacterial meningitis related to age?

Neonates: listeria, group B streptococci, E. coli
Children: H. influenza
10 to 21: meningococcal
21 onward: pneumococcal >meningococcal
Elderly: pneumococcal>listeria

20

What are the common causes of bacterial meningitis related to RFs?

Decreased CMI: listeria
S/P neurosurgery or opened head trauma: Staphylococcus, Gram Negative Rods
Fracture of the cribiform plate: pneumococcal

21

What is the likely causative organism in bacterial meningitis due to an immunocompromised state?

S. pneumoniae
N. meningitidis
Listeria
aerobic GNR (including Ps.aeruginosa)

22

What is the likely causative organism in bacterial meningitis due to a basilar skull fracture?

S. pneumonia
H. influenzae
beta-hemolytic strep group A.

23

What is the likely causative organism in bacterial meningitis due to head trauma or post-neurosurgery?

S.aureus
S.epidermidis
aerobic GNR

24

What is the likely causative organism in bacterial meningitis due to a CSF shunt?

S. epidermidis
S. aureus
aerobic GNR
Propionibacterium acnes

25

What can be some long term effects of meningitis and septicaemia?

Limb loss
Deafness
Blindness
Cerebral palsy
Quadriplegia
Severe mental impairment

26

What is the pathogenesis of bacterial meningitis?

1. Nasopharyngeal colonisation
2.Direct extension of bacteria: parameningeal foci (sinusitis, mastoiditis, or brain abscess), across skull defects
3. From remote foci of infection: (e.g. endocarditis, pneumonia, UTI etc)

27

What are some agents of meningitis in immunocompromised patients?

Conventional agents- s.pneumonia, s.aureus etc
Listerio monocytogenes
Mycobacterium tuberculosis
Nocardia asteroides
Cryptococcus neoformans (AIDS)

28

What does Neisseria meningitides cause?

Meningococcal meningitis

29

What are the symptoms in meningococcal meningitis due to?

Endotoxin from bacteria

30

In whom does Meningococcal meningitis most commonly occur?

Young children

31

What are military recruits vaccinated with to prevent outbreaks of meningococcal meningitis in training camps?

Purified capsular polysaccharide

32

What type of H. influenza is the most common cause of meningitis in children under 4yo?

Type B

33

Where is S. pneumoniae commonly found in the nasopharynx?

Nasopharynx

34

Who are most susceptible to S. pneumonia meningitis?

Hospitalised patients, patients with CSF skull fractures, diabetics, alcoholics and young children

35

What does the conjugate vaccine for pneumoccal pneumonia always provide protection against?

Pneumococcal meningitis

36

What is listeria monocytogenes?

Gram +ve bacilli

37

What cultures should be taken in suspected listeria monocytogenes meningitis?

Blood cultures

38

Who are most likely to have listeria monocytogenes meningitis?

Neonates
>55yo
Immuno-suppressed esp. malignancy

39

What is the antibiotic of choice in listeria monocytogenes meningitis?

IV Ampicillin/Amoxicillin
Ceftriaxone has no value as intrinsically resistant

40

Describe tuberculous meningitis

Can reactivate in elderly
Often non specific ill health
Previous TB on CXR
Poor yield from CSF

41

How is tuberculous meningitis treated?

Isoniazid + rifampicin (add pyrazinamide + ethambutol)

42

Describe cryptococcal meningitis?

Fungal
Mainly HIV
CD4

43

How should cryptococcal meningitis be treated?

IV Amphotericin
B/Flucytosine
Fluconazole

44

What are the clinical signs of bacterial meningitis?

Fever
Stiff neck
Alteration in consciousness

45

What are some signs and symptoms in bacterial meningitis?

Headache
Vomiting
Pyrexia
Neck stiffness
Photophobia
Lethargy
Confusion
Rash

46

Who are signs of bacterial meningitis often absent or atypical in?

Very young/old
Immunocompromised

47

What DDx should be suspected in possible bacterial meningitis?

Meningitis
Encephalitis
Cerebral abscess
Severe sepsis from other source
SA haemorrhage
Cerebral tumour

48

What is the rule regarding LP's and bacterial meningitis?

LP is CSF pleocytosis, not symptoms of bacterial meningitis

49

What should be in each LP tube for interpretation?

Tube 1. Haematology: cell count, differential
Tube 2. Microbiology: gram stain, cultures
Tube 3. Chemistry: glucose, protein
Tube 4. Haematology: cell count, differential

50

How should meningitis be diagnosed?

Blood cultures
Throat swab (meningococci)
Blood EDTA for PCR (meningococci)
CSF (LP)
Microscopy, biochemistry, culture, antigen detection

51

What bacteria will be found in the ddx of meningitis in normal patients?

Enteroviruses
HSV1, HSV2
VZV
M. tuberculosis
B. burgdorferi
Pneumococci
Meningococci
H. influenza

52

What bacteria will be found in the ddx of meningitis in immunocompromised patients?

EBV
CMV
HHV-6/7
T. gondii
JC virus

53

What are the CSF findings in viral acute adult meningitis?

10^1-10^3 cells (lymphocytes)
Negative gram stain
Negative bacterial antigen detection
Normal or slightly high protein
Usually normal glucose

54

What are the CSF findings in bacterial acute adult meningitis?

10^1-10^4 cells (predominantly polymorphs)
Positive gram stain
Positive bacterial antigen detection
High protein
Less than 70% glucose

55

What are the CSF findings in tuberculous acute adult meningitis?

10^1-10^3 cells (predominantly lymphocytes)
Positive or negative gram stain
Negative bacterial antigen detection
High or very high protein
Less than 60% glucose

56

What test results are predictive of bacterial meningitis with 99% accuracy?

WBC >2000
Neutrophils >1180
Protein >220mg/dl
Glucose

57

If not bacterial meningitis, what infectious conditions may cause neutrophilic pleocytosis and low csf glucose?

Viral meningitis (early phase only)
Some parameningeal foci/ cerebritis
Leakage of brain abscess into ventricle
Amebic meningoencephalitis
TB meningitis (rarely, & usu. only early)

58

If not bacterial meningitis, what non-infectious conditions may cause neutrophilic pleocytosis and low csf glucose?

Chemical-meningitis (contrast…)
Behcet syndrome
Drug –induced ( NSAIDs, Sulfa, INH, IVIG, OKT3…)

59

What is aseptic meningitis?

A term used to mean non-pyogenic bacterial meningitis
It describes a spinal fluid formula that has:
low number of WBC
minimally elevated protein
normal glucose

60

What are some infectious treatable causes of aseptic meningitis/encephalitis syndrome?

HSV 1 and 2
Syphilis
Listeria (occasionally)
Tuberculosis
Cryptococcus
Leptospirosis
Cerebral malaria
African tick typhus
Lyme disease

61

What are some non-infectious treatable causes of aseptic meningitis/encephalitis syndrome?

Carcinomatous
Sarcoidosis
Vasculitis
Dural venous sinus thrombosis
Migraine
Drug:
Co-trimoxazole
IVIG
NSAIDS

62

What are the adult bacterial meningitis guidelines?

Pre-hospital management
Early inpatient management
Antimicrobial adjunctive treatment
Supportive therapy
Prevention of secondary cases of meningitis
Screening for predisposing factors to meningitis

63

What management occurs in pre-hospital acute adult bacterial meningitis?

Look for indications for hospital admission
Pre-hospital antibiotics

64

What are some indications for hospital admission of acute adult bacterial meningitis?

Signs of meningeal irritation
An impaired conscious level
A 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

65

What should happen immediately on hospital admission in acute adult bacterial meningitis, provided ABC is fine?

Bloods for culture and coag screen
Antibiotic treatment before pathogens are identified, and immediately after
Throat swab which should be plated soon as practical
Disrupt and swab/aspirate any petechial or purpuric skin lesion for microscopy and culture
CT/MRI for patients with papilloedema or focal neuro signs

66

Who should undergo CT prior to LP?

Immunocompromised
History of CNS disease
New onset seizure (within 1 wk of presentation)
Papilloedema
Abnormal level of consciousness
Focal neurologic deficit

67

What are some key warning signs in acute adult bacterial meningitis?

Marked depressive conscious level (GCS 2)
Focal neurology
Seizure before/at presentation
Shock
Bradycardia and HT
Papilloedema

68

Who should undergo an LP in acute adult bacterial meningitis?

All adults with suspected meningitis except when a clear contraindication exists, or if there is a confident clinical diagnosis of meningococcal infection with a typical rash

69

What is the empiric antibiotic therapy for acute adult bacterial meningitis?

IV Ceftriaxone 2g bd
Add IV Ampicillin/amoxicillin 2g qds if listeria suspected
(If pen allergic Chloramphenicol IV 25mg/kg 6-hourly with vancomycin IV 500mg 6-hourly or 1g 12 hourly

70

What treatment should be given in acute adult bacterial meningitis if listeria is suspected and patient is pen. allergic?

Co-trimoxazole

71

What additional drug therapy other than antibiotics should be given to all patients with suspected bacterial meningitis?

Steroids 10mg IV 15-20 min before or with first antibiotic dose, then every 6hrs for 4 days

72

When should steroids not be given in bacterial meningitis?

Post surgical meningitis, severe immunocompromised, meningococcal or septic shock or those hypersensitive to steroids

73

What indicates a poor prognosis on admission in meningococcal disease?

Haemorrhagic Diatheses
Deteriorating consciousness
Multi-organ failure
Rapidly developing rash
Age >60

74

What are key interventions in management of bacterial meningitis with low GCS (2)?

Admit to highly supervised area- baseline investigations
Secure airway and high flow O2
IV 2G Ceftriazone stat (+- amoxicillin if >55 to cover listeria)
IV corticosteroids
Do not wait for CT/LP

75

What is the standard contact prophylaxis regimen in bacterial meningitis?

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).

76

What vaccines against organisms which can cause meningitis exist?

Neisseria meningitidis: serogroups A and C (W135 & Y)- travel. Group C conjugate vaccine
H. influenza (HiB vaccine)
Strep. pneumoniae- pneumocccal vaccines-polysaccharide and conjugate

77

What indicates a poor prognosis on admission in all types of meningitis?

Tachycardia
GCS <12 on admission
Low GCS, cranial nerve palsy
Seizures within 24hr
Hypotension on admission
Age >60