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Microbiology > CNS & Meningitis > Flashcards

Flashcards in CNS & Meningitis Deck (43):
1

What are the causative agents for meningitis?

NM
Strep pneumo
H influenzae
TB
Various viruses
Cryptococcus neoformans

2

What are the causative agents of encephalitis?

Rabies virus
Arbovirus
Trypanosoma species
Prions
Amoeba

3

What are the causative agents of myelitis?

Poliovirus

4

What are the causative agents of neurotoxin?

Clostridium tetani
Clostridium botulinum

5

What is meningitis?

Inflammatory process of meninges and CSF

6

What is meningoencephalitis?

Inflammation of meninges and brain parenchyma

7

What is the neurological sequlae of meningitis?

Direct bacterial toxicity (endotoxins from gram neg, E. coli, NM, pos produce exotoxinss in ecellular space, s aureus
Indirect inflammatory process and cytokines release and oedema
Shock, seizures, and cerebral hypoperfusion

8

What is the mortality rate of meningitis?

10%, 5% survivors have neurological sequlae, sensineural deafness

9

What is the classification of meningitis?

Acute- bacterial
Chronic- TB, spirochetes (syphilus), Cryptococcus
Aseptic- acute viral

10

What are the causes of acute meningitis?

NM
Strep pneumo
H influenzae type B

11

What are the less common causes of acute meningitis?

Listeria - alcoholics with diabetes, soft cheese
Group B strep neonates, vaginal colonisation
E. coli neonates

12

What about NM?

Infectious cause of childhood death in all countries
Person to person, symptomatic carriers
Pathogenic strains found in 1% of carriers
Nasopharyngeal mucosa in susceptible individual
Infections in less than 10 days

13

What ins the dermatological presentation of meningococcal meningitis?

Nonblanching purpuric rash 80%
Maculopapular rash 13%
No rash 7%

14

Vaccines re: NM?

Present- type C
Absent- A, Y, W135, and B which is common in UK (antigenic shift)

15

What are the clinical outcomes of NM?

Meningitis- 50%
Septicaemia- 7-10%
Both- 40%
Tx is different for hypotension and raised ICP

16

What happens if you give steroids in septicaemia?

You suppress their immunogenicity which is keeping them alive
If meningitis- oedema, vasodilation is harmful, steroids help.

17

What CT signs can be seen with chronic meningitis?

Enhancement in the basal cistern and meninges with dilation of ventricles

18

What about TB chronic meningitis?

Incidence 544 per 100000
Immunosuppressed
Meninges, basal cisterns.
Granulomas, absecces, cerebritis

19

How do you manage chronic meningitis?

DO NOT manage chronic meningitis- refer to specialist
Supportive neurosurgeons
Radiologists
Pharmacists

20

What about aseptic meningitis?

Most common infection of CNS
Non specific rash can accompany symptoms
Coxsackie group B and echovirus 80-90 % cases in which a causative organism is identified

21

What are the viral causes of CNS infections in children, infants, young adults?

Mumps
Measles
Varicella zoster
Epstein Barr, cytomegalovirus
Other- myxovirus, paramyxovirus, adenovirus

22

What are the viral causes of CNS infections in adults?

Enterovirus- coxsackie, echo, polio. All ages.
Herpes simplex 1-2 high dose IV acyclovir won't alter course. Crystallises renal tract.
Summer autumn.

23

What is the presentation of encephalitis?

Headache, neck stiffness, confusion

24

What is the transmission for encephalitis?

Person to person, or vectors
Mosquitoes
Lice
Ticks
Various viridae from Togavirus, Flavivirus, Bunyavirus

25

What should you do for herpes simplex encephalitis?

High dose IV acyclovir

26

Which virus is becoming leading cause of viral encephalitis?

West Nile virus
Birds migrate to New York and bring mosquitoes
Italy

27

What are the other infectious causes of encephalitis?

Bacterial- listeria
Amoebic- naegleria fowleri, habitat warm water
acanthamoeba species, balamuthia mandrillaris- brain abcess, aseptic or chronic meningitis. South west England, Bath.

28

What is a non bacterial, non viral cause of encephalitis?

Toxoplasmosis, obligate intracellular protozoal parasite
Oral, transplacental, organ transplantation
Immunocompromised
Grey and white matter of brain, retina, alveolar, heart, skeletal muscle

29

Brain abcess pathophysiology?

Otitis media,mastoiditis, parasinuses, endocarditis, haematology

30

What is the microbiology of brain abcess?

Streptococci, staph, gram neg, TB, fungi, parasite, actinomycetes, nocardia species

31

What is the common form of vertebral infection?

(Htlv1- transverse myelitis, polio)
Pyogenic vertebral osteomyelitis, IVDU
Direct open spinal trauma, infections in adjacent structure, haematogenous spread
Left untreated, neurological deficits, spinal deformity, death.

32

What are the risk factors for spinal infections?

Advanced age
IVDU
Long term systemic steroids
DM
Organ transplantation
Malnutrition
Cancer

33

What imaging is the best?

Contrast MRI - detecting parenchymal abnormalities such as abcess and infections
CSF sample, brain tissue.

34

What other samples can you get for meningitis case?

Blood culture
Blood for PCR
Throat swab

35

What is the microscopy for purulent meningitis?

Turbid, 100-200 polymorphs, high protein, low glucose

36

What is the microscopy for aseptic meningitis?

Slightly turbid, lymphocytes, high protein, normal glucose
(Partially treated bacterial meningitis)

37

What is the microscopy for TB meningitis?

Slightly turbid, lymphocytes, high protein, low glucose

38

What is the link with HIV and cryptococcus meningitis?

Immunocompromised, opportunitistic infection
Indian ink stain

39

What are the limitations of diagnostics?

MRI oedema pattern cannot be differentiated from tumour/stroke/vasculitis
Early infection and serological tests
Amount of CSF
PCR techniques
Methods to detect amoebic infections
Availability of good lab technique

40

What is the management approach?

Hx, empirical abx, LP
CSF analysis
CSF culture

41

What is the therapy for meningitis?

Ceftriaxone 2g IV bd
If >50 years or immunocompromised add amoxicillin 2g IV 4 hourly

42

What is the therapy for meningitis- encephalitis?

Aciclovir 10mg/kg IV tds
Ceftriaxone 2g IV bd
If more than 50 years or immunocompromised add amoxicillin 2g IV 4 hourly, covers listeria

43

What are the 4 routes of entry?

Haematogenous spread
Direct implantation via instrumentation
Local extension secondary to established infections
PNS to CNS- viruses