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Streptococci Flashcards

(50 cards)

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1
Q

Strep description

A

G+ve
Cocci
Usually in chains
Commensal and pathogenic on skin and mucous mems

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2
Q

Classification

A

Grps: pyogenic, enterococci, oral, lactic, other

Based on factors incl haemolysis, Ce antigs and fermentation properties

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3
Q

Beta haemolytic

A

Complete haemolysis (clear zone produced)

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4
Q

Alpha haemolytic

A

Incomplete haemolysis or green discolouration

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5
Q

Non haemolyctic or gamma haemolytic

A

No haemolysis

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6
Q

CW antigen classification

A

Basis for lancefield test
Carbs from polysacc, teichoic and lipoteichoic acid in the CW
Other serological diff (eg M pro) allow further subdivision

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7
Q

Carb fermentation

A

Range of sugars fermented somewhat correlates to species

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8
Q

Pyogenic strep summary

A

Long chains
Beta haem
A B C G L lancefield grps

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9
Q

Viridans summary

A

Long chains
Alpha haem
Not typable by lancefield

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10
Q

Pneumococci summary

A

Pairs
Alpha haem
Not typable by lancefield

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11
Q

Enterococci summary

A

Short chain
Any haem
D grp lancefield

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12
Q

Lancefield process

A

Extracted with hot HCL wnd ppt with Ab from rabbits
Refer to as gro polysacc and assigned letter
21 grps IDed but ltd prac value

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13
Q

Human strep

A

Pyogenes (A)

Agalactiae (B)

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14
Q

Canine strep

A

Canis (G)

Pneumoniae (NT)

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15
Q

Equine strep

A

Equi
Equisimilis
Zooepidemicus
All C

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16
Q

Cattle strep

A

Zooepidemicus (C)
Agalactiae (B)
Dysgalactiae (C)
Uberis (NT)

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17
Q

Pig strep

A

Suis (D)

Porcinus (E)

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18
Q

Strep equi

A

C
Obligate parasite
Not commensal but can be ‘carried’ in tonsils and guttural pouch asympt
Cause strangles

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19
Q

Strangles symptoms early

A

Abrupt fever 103+ degrees c
Pharyngitis causing dysphagia neck extended listless depressed reluctant to eat
Pharyngitis laryngitis rhinitis may contrib to nasal discharge

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20
Q

Later strangles symptoms

A

Lymphadenopathy sub mand and retropharyngeal l nodes equally involved
Painful oedema
Swollen and painful a wk post
Serum ooze from overlying skin for days before rupture
Drains tenacious creamy pus

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21
Q

What is strangles

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A

Highly contagious resp disease affecting horses under 5 potentially fatal
Causes major farm disruption and there is widespread distribution
Suppurative pharyngitis and lymphadentis

22
Q

How are zooepidemicus and equisimilis differ from equi

Study These Flashcards
A

Often present as nasopharyngeal colonisers in normal horses but less host adaptive, both opportunistic pathogens causing mastitis local sepsis endometritis abortion endocarditis etc
Zooepi can cause infection of resp tract secondarily eg to influenza

23
Q

What is bastard strangles

Study These Flashcards
A

Normal strangles mainly restricted to upper airways but. Septicaemia resulting from strangles due to metastasis to other locations
Involves bacteraemia and abscesses in other lymph nodes, organs of thorax and abdomen rarely infect brain too
Haemorrhagic purpura can occur (widespread blood vessel damage, swelling of head legs and bruise like patches on mouth)
Often fatal

24
Q

Strangles pathogenesis

Study These Flashcards
A

Inflam resp to invasion cause neutro and serum influx
Many strep virulence factors interfere with phagocytosis
Destruction of bact and phagosome causes viscous mix of protease, lytic enz and dead cells that extend area of tissue damage

25
How do bact protect themselves from opsonisation
M pro and capsule and cause host cell lusis by secr streptolysinsnakd othe EC enz
26
Virulence factor: peptidoglycan
Chemotactic for PMNs and pyrogenic
27
Virulence factor: fibronectin binding pros
Involved in cellular invasion
28
Virulence factor: M pro and M like pro
Req for virulence Pro fibril allowing to bind fibrinogen fibrin and their degradation products to form dense coat over bacteria to protect from complement Also protect against opsonisation by bind factor H M like bind fibronectin IgA and G to aid evasion
29
Virulence factor: ZAG pro
Bind Ab Fc part
30
Virulence factor: capsule
Protect against phagocytosis | Weakly immunogenic
31
Virulence factor: C5a peptidase
Cleave C5a
32
Virulence factor: hyaluronidase NADase and streptokinase
H: facilitate spreading in tissues S: break down fibrin clots N: inhib PMN activity and is leukocidal
33
Virulence factor: SLO and SLS
SLO: O2 labile. Bind cholesterol in mem to form pores SLS: O2 stable. Both contrib to pyogenic strep beta haem Induce cytok release and active against leukocyte chemotaxis degran and lysis
34
Virulence factor: superoxide dismutase
Neutralise antibac O2 free radicals prod
35
Virulence factor: degradative enz
Release nutrients from host
36
Virulence factor: strep pyrogenic exotoxins
Prod by some strains Mainly grp A Superantigens so are highly pro inflam and immunomodulatory
37
Strangles diagnosis
Nasopharyngeal swab and culture or wash or pus from abscess on columbia blood agar Can hive -ve result, washes are more sensitive esp during early incubation if you spin down wash and culture the pellet. PCR detection much more sensitive
38
Strangles epidemiology
Purulent discharge Horse-horse contact Indirect transmission Carriers
39
Strangles treatment
Penicillin, most are resistant to eg ampicillin | Not always effective
40
Immunity after natural strangles infection
75% dev over 5yr long imm | So a giid vacc should be feasible
41
Vacc possibilities
M pro and capsules poorly antigenic but can induce spec IgG and A giving partial/complete imm Ab also prod to haemolysins M pro considered as potential vacc immunogen No reliable vacc yet, approacge involving m pro have failed to prevent outbreaks
42
Control during strangles outbreak
Stop horse movement in and out Quarantine Antibio treatment
43
Control of strangles after clinical recovery
Over 3 swabs at 1 wk intervals Quarantine Strict hygiene introduced
44
Strep mastitis caused by
Grp A aka Pyogenes mainly in humans | Other grps more predom in animals
45
Mastitis by agalactiae
Grp B Chronic contagious bovine mastitis Obligate mammary gland parasite Adhere to and grow along the teat and duct sinuses causing mild, chronic inflam and fibrosis Can cause small duct blockage and loss of milk prod capacity
46
Mastitis by dysgalactiae
Grp C commensal of mouth and udder May invade wounds and cause mastitis or summer mastitis in assoc with arcanobacterium pyogenes Acute can cause permanent quarter damage
47
Mastitis by uberis and parauberis
Untypable viridan like Surf commensals Can cause mastitis under poor enviro or management conditions Survives and transmitted via bedding Enviro mastitis Can occur during dry period and may be severe
48
Strep suis
Endemic in pig industry Usually asympt can cause septicaemia meningutis pneumonia and arthritis Young pigs most at risk
49
Strep suis predisposing factors
Poor housing with inadeq ventilation | Esp if under intensive conditions that can cause stress leading to imm suppr
50
Strep suis in humans
Most recent outbreak coincided with pig outbreak No human to hunan transmission All affected in contact with pigs Most people affected had typical strep TSS symptoms High morbidity and mortality rate Now under WHO surveillance

Bacteriology (15 decks)

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