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Medicine Unit 6 > Microbiology of meningitis > Flashcards

Microbiology of meningitis Flashcards

1
Q

meningitis definition

A

inflammation of the meninges
can be caused by bacteria, viruses and protozoa

other causes: cancer, inflammatory diseases and drugs

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2
Q

encephalitis definition

A

inflammation of the Brian and severity is variable
causes are HSV, parasites, autoimmune diseases, certain medications

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3
Q

what is the CNS composed of

A

brain and spinal column

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4
Q

cerebra-spinal fluid

A

clear fluid
occupies subarachnoid space and ventricular system
around and inside brain and spinal cord
cushions brain

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5
Q

infections of the CNS

A

normally sterile and well protected
has poor immune function
infections generally originate from the bloodstream
severe trauma may result in CNS infection

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6
Q

meninges definition

A

system of protective membranes enveloping CNS

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7
Q

label the image

A
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8
Q

what is the blood brain barrier

A

separation of circulating blood and the CSF in the central nervous syste m

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9
Q

vasogenic brain oedema cause

A

BBB injury
with association alteration in albumin transcytosis
in many forms of CNS infections

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10
Q

tight junctions

A

zonula occludens
closely associated areas of 2 cells whose membranes join together forming virtually impermeable barrier to fluid

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11
Q

meningitis with antibiotics

A

risk of neurological disorders

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12
Q

meningitis without antibiotics

A

high mortality rate

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13
Q

symptoms of meningitis

A

fever
photophobia
nuchal rigidity
altered mental status
purpuric rash
headache

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14
Q

common meningitis pathogens in neonates

A

E coli
group B streptococci
listeria monocytogenes

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15
Q

common meningitis pathogens in infants/children and adults

A

Neisseria meningitidis
strep pneumoniae
haemophilus influenza

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16
Q

common meningitis pathogens in immunosuppressed patients

A

cryptococcus neofromans
l. monocytogenes

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17
Q

Nuchal rigidity

A

stiff neck
sign of meningeal irritation
present when the neck resists passive flexion

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18
Q

Kernigs sign

A

elicited with patient in supine position
thigh is flexed on abdomen with knee flex
elicit pain when knee extends

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19
Q

Brudzinskis sign

A

elicited with the patient in the supine position
positive when passive flexion of the neck results in spontaneous flexion of the hips and knees

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20
Q

Glass test

A

purpuric rash that doesnt fade under pressure
sign of meningococcal septicaemia

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21
Q

what are the common meningitis pathogens

A

streptococcus pneumoniae
group B streptococcus
neisseria meningitidis
haemophilus influenzae
listeria monocytogenes
escherichia coli

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22
Q

label the image to display Neisseria meningitidis interaction with the BBB

A
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23
Q

label the image of pathophysiology of meningitis

A
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24
Q
A
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25
26
neisseria meningitidis
gram negative diplococcus, intracellular
27
what is in the image
Neisseria meningitidis
28
pathogenicity factors of meisseria meningitidis
type IV pilus involvedi n mucosal colonisation polysaccharide capsule helps avoid phagocytosis major toxin: lips-oligosaccharide endotoxin
29
what are the 6 serotypes of N.meningitidis
A B C W X Y
30
type IV pilus in mucosal colonisation
main means of meningococcal adhesion onto host cells
31
pilus-mediated adhesion
induces formation of microvilli-like structures at the site of interaction trigger bacterial internalisation
32
consequence of pill-induced signalling
reorganisation of actin cytoskeleton leads to formation of membrane protrusions engulfing bacterial pathogens into intracellular vacuoles polysaccharide capsule helps avoid phagocytosis
33
major toxin
lips-oligosaccharide endotoxin
34
NMEC
neonatal meningitis E coli type of extra intestinal E coli commonly inhabits in GI tract, perinatal transfer form mother most frequent cause of gram-negative meningitis in neonates
35
NMEC important factors in pathophysiology
K1 capsule OMPA and type 1 pili for adhesion and invasion CNF-1 and IbeA for invasion
36
attachment of NMEC
mediated by type 1 pili binding to CD48 and OmpA (outer-membrane protein A) binding to ECGP96
37
NMEC invasion
involves cytotoxic necrotizing factor 1 (CNF1) binding to 67 kDa laminin receptor (67LR; also known as RPSA) as well as type1 pili and OmpA binding their receptors.
38
39
why is NMEC protected from the host immune response
by its K1 capsule invasion into macrophages may provide replicative niche for high bacteraemia allows generation of sufficient bacteria to cross BBB
40
categories of NMEC pathogenicity factors
adhesions immune evasion iron acquisition invasion factors toxins
41
NMEC adhesins
OmpA S-fimbriae- bind sialic acid of human cell surface glycoproteins (type 1 pili)
42
NMEC immune evasion
K1 capsule, antiphagocytic
43
iron acqusition NMEC
enterobactin
44
NMEC innvasion factors
IbeA receptor binding
45
NMEC toxins
cytotoxic necrotising factor CNF1
46
processing of lumbar puncture
appearance cell count centrifugation gram stain culture further tests
47
CSF appearance: clear/colourless
normal
48
CSF appearance: turbidity
WBC's possibly other cells seen in microscopy
49
CSF appearance: red staining
RBC's present stroke/ haemorrhage
50
hallmarks of bacterial meningitis in CSF count
recruitment of leukocytes into CSF WBC's are polymorphonucleus, lymphocytes bacterial meningitis has high WBC count viral and TB meningitis has lower WBC count
51
in case of some WBC's increase but bacteria isn't visible
patient has meningitis but the bacteria killed by antibiotics early stage meningitis need to do antigen detection, capsule is highly antigenic e.g. latex bead assays PCR testing for rapid diagnosis
52
PCR testing for rapid diagnosis
alternative to antigen testing confirmation of gram staining specific primers broad-range/ universal primers
53
typical approach for fungi and parasites
microscopy culture antigen detection PCR
54
treatment of bacterial meningitis
commence ASAP before microbiological diagnosis high dose intramuscular or IV benzylpenicillin given at earliest opportunity high does IV 3rd generation cephalosporin antibiotic susceptibility may modify treatment household contacts may be given prophylactic antibiotics
55
TB meningitis treatment
long term treatment with specialised anti-tubercular/ antifungal agents
56
3rd generation cephalosporins in meningitis
ceftriaxone or cefotaxime or broad spectrum activity vs gram positives and gram negatives penetrate well into CSF
57
different meningitis vaccines
meningitis B 6 in 1 pneumococcal Hib/Men C meningitis ACWY
58
6 in 1 vaccine
also known as the DTaP/IPV/Hib/Hep B vaccine, offers protection against diphtheria, tetanus, whooping cough, hepatitis B, polio and Haemophilus influenzae type b (Hib).
59
common causes viral meningitis
enteroviruses HSV-2 HIV LCMV arbovirus mumps
60
less common causes of viral meningitis
HSV-1 CMV EBV VZV adenovirus measles rubella
61
rare causes of viral meningitis
influenza parainfluenza rotavirus vaccinia encephalomyocarditis virus
62
treatment of acute viral meningitis
primarily symptomatic and includes use of analgesics, antipyretics and antiemetics oral or IV acyclovir for HSV-1 or 2 and severe EBV or VZV

Medicine Unit 6 (23 decks)

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