IMED2001 > Lecture 3 > Flashcards

Lecture 3 Flashcards

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1
Q

list the stages of infection

A

transmission
adherence
colonisation
invasion
evade immune system
disease

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2
Q

3 ways that disease can get transmitted?

A
  1. animal reservoir
  2. vector
  3. environment contamination
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3
Q

in which stages of infection does innate immunity act

A

adherence stage

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4
Q

in which stages of infection does adaptive immunity act

A

colonisation

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5
Q

which cocci has -ve catalase reaction?

A

streptococcus

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6
Q

which cocci has +ve catalase reaction?

A

staphylococcus

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7
Q

which bacteria shapes are aerobic?

A

rod/bacilli

cocci

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8
Q

what does catalase enzyme break down?

A

h2o2

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9
Q

coagulase positive staphylococcus

A

s.aureus

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10
Q

coagulase negative staphylococci (CoNS)

A

s. epidermis
s. saprophyticus
s. lugdunesis

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11
Q

describe the test used staphylococcus coagulation

A

blood
spun down into
plasma
bacteria added to plasma
clot = coagulation

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12
Q

what does s.aureus + plasma do?

A

activated clotting cascade
then
coagulates plasma

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13
Q

describe how staphylococci are catalase positive?

A

staphylococci produce catalse enzyme

catalase enzyme breaks down h2o2 into h2o + o2

visible reaction of bubbles occurs

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14
Q

where are CoNS mostly found

A

normal skin flora of humans

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15
Q

CoNS. high or low virulence?

A

low

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16
Q

in which situations does CoNS become pathogenic?

A
  1. skin barrier breached
  2. invasive devices
  3. premature infants
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17
Q

what is s.lugudunesis?

A

tissue destructive enzyme

infection in heart, bone, prosthetic joints

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18
Q

what is s.saprophyticus?

A

UTI in young, sexually active women

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19
Q

how many people are carriers of s.aureus?

A

20-40%

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20
Q

s.aureus affects which body parts?

A

anterior nares
skin of axilla
skin of groin

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21
Q

s.aureus can cause _______ or ______ infections

A

localised or disseminated

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22
Q

example of localised infection of s.aureus?

A

brain abscess

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23
Q

example of disseminated infection of s.aureus?

A

disseminated can progress to endocarditis

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24
Q

coagulase toxin role in pyogenic infection

A

walls of infection

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25
lytic toxins example
haemolysins and proteases
26
lytic toxin role in pyogenic infection
destroys tissue in the abscess
27
which s.aureus strains cause non-pyogenic infection
toxin producing strains
28
example of s.aureus strains non-pyogenic infections
staphylo scalded skin syndrome staphylo toxic shock syndrome staphylo food poisoning
29
what does quorum signalling depend on?
environmental conditions
30
gene regulator for quorum signalling
Agr A
31
what does Agr A do?
turns commensal bacteria into a pathogen (e.g. endocarditis)
32
explain how inflammatory response and t cell activation happen in staphylo scalded skin syndrome
1. bacteriophage acquired by transduction 2. carry gene for enterotoxin 3. enterotoxin crosslinks t cell and mhc II 4. enterotoxin bypasses antigen presentation 5. polyconal activation of t cell 6. inflammatory cascade
33
what determines if s.aureus will be commensal or pathogenic
quorum signaling - agr a
34
blood agar appearance of streptococcus alpha haemolysis
partial haemolysis of agar olive-green tinge
35
blood agar appearance of streptococcus beta haemolysis
blood dissolved agar transparent
36
blood agar appearance of streptococcus gamma haemolysis
nothing
37
explain the further classification of beta haemolytic streptococci
lancefield grouping system - 20 groups
38
2 beta haemolytic streptococci with clinical significance
LGA - steptococcus pyogenes LGB - steptococcus agalactiae
39
primary infections caused in throat by streptococcus pyogenes?
pharyngitis tonsilitis
40
suppurative throat infections caused by streptococcus pyogenes can extend into where?
causes extension of disease into sinus/mastoid
41
non-suppurative throat infections caused by streptococcus pyogenes develop into what?
acute rheumatic fever if recurrent fever then rheumatic heart disease but also acute glomerulonephritis
42
primary infections caused in skin by streptococcus pyogenes?
cellulitis impetigo
43
suppurative skin infections caused by streptococcus pyogenes can develop into what?
necrotising fasciitis
44
non-suppurative skin infections caused by streptococcus pyogenes develop into what?
acute glomerulonephritis but also acute rheumatic fever
45
where is steptococcus agalactiae colonies found?
UT and rectum of women
46
who gets infected with steptococcus agalactiae?
neonates - passed on during/after childbirth
47
infections caused by steptococcus agalactiae in neonates?
meningitis bloodstream infections
48
explain antigenic cross reactivity in acute rheumatic fever caused by strep A
proteins produced by strep A/strepotococcus pyogene are very similar to proteins in heart tissue so, tissues in heart resemble the antigens produced by strep a antibodies and t cells also the strep a AND heart tissues
49
who is acute rheumatic fever common in?
aboriginal children children in poverty
50
symptoms of acute rheumatic fever?
arthritis rash carditis writhing movements
51
where are commensals of alpha haemolytic streptococci found?
oropharynx nasopharynx genital tract gut
52
two groups of alpha haemolytic streptococci?
1. viridians 2. streptococcus pneumoniae
53
s.mutans in a part of the __________
viridians groups of streptococci
54
evolution of s.mutans
1. fermented foods 2. lactic acid bacilli + oral streptocci 3. horizontal gene transfer + gene duplication + selective pressures (eating sugar) 4. oral streptococci acquired the GTF gene
55
pathogenesis of dental caries/s.mutans
1. sugar = increase growth of s.mutans 2. s.mutans produce GTF 3. GTF breaks down sucrose into - glucans 4. glucans build up - form ploysaccharide matrix (biofilm) 5. biofilm produces organic acids (lactic acids) 6. decrease in ph = demineralisation, carious process, cavities
56
infections cause by streptoccus pneumoniae
pneumonia meningitis
57
_____ types of polysaccharide capsule in streptococcus pneumoniae
794
58
why is polysaccharide capsule in streptococcus pneumoniae important?
1. invasive species - capsule protects against phagocytosis 2. vaccines only protect against specific serotypes
59
who mostly gets infected by streptococcus pneumoniae?
mostly children nasopharyngeal carriage
60
is streptococcus pneumoniae invasive?
yes
61
explain conjugate vaccine
polysaccharide vaccine is based on bacteria capsule no persistent immune response in children conjugate vaccine: polysaccharide vaccine + carrier protein induces memory response in children decreased nasopharyngeal carriage + decreased transmission
62
Conjugate vaccines against ________________, pneumococcus and meningococcus serogroups C, A, W, and Y have contributed to the virtual elimination of _____________ caused by these bacteria and prevent more than a million deaths annually Dendritic cell T cell dependent response
Conjugate vaccines against Haemophilus influenzae type b (Hib), pneumococcus and meningococcus serogroups C, A, W, and Y have contributed to the virtual elimination of bacterial meningitis caused by these bacteria and prevent more than a million deaths annually Dendritic cell T cell dependent response
63
when can stage of infection go from colonisation straight to disease?
if the bacteria produces toxins
64
2 pathways from immune evasion to disease
1. immune evasion to diseases 2. immune evasion - latency - disease
65
skin infections caused by s.aureus
* folliculitis * furuncles (boils) * carbuncles * impetigo * cellulitis * wound infections
66
localised infections cause by staph aureus
lung abscess brain abscess mastitis
67
in which s.aureus strain does enterotoxin bypass normal antigen presentation?
staph scalded skin syndrome
68
how many groups in the lancefield grouping system and which letter ranges are present?
20 groups A-H K-V
IMED2001
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