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MICROBIOLOGY II > Lecture 2 - Streptococcal Infection > Flashcards

Lecture 2 - Streptococcal Infection Flashcards

(59 cards)

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1
Q

Where are strep found

A

Everywhere

Gut, GI tract, mouth, URT

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2
Q

What is the classification of streptococcal

A

Streptococci

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3
Q

What is the pathogenic form of streptococcus

A

Strep pyogenes - Group A streptococcus

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4
Q

Who first described pyogenes infected patients with a ‘flesh eating disease’

A

Hippocrates

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5
Q

Who in 1874 designated the name strepto coccus

A

Theodore Billroth

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6
Q

Who in 1884 was the first person to recover and grow strep pyogenes from patients with puerperal sepsis (childbed fever)

A

Louis Pasteur

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7
Q

In 1884 which pioneer designated name streptococcus pyogenes

A

Anton rosenbach

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8
Q

Why is it called pyogenes

A

Pyo meaning inflammatory

Cause inflammation

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9
Q

Is strep pyogenes gram positive or gram negative

A

Gram positive

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10
Q

What is the size of strep pyogenes

A

0.5-1um

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11
Q

How do strep pyogenes gain energy E.g. Via oxygen or co2

A

FACULTATIVE ANAEROBES

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12
Q

What does capnophilic mean

A

Bacteria that live in high CO2

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13
Q

What temperate range does strep pyogenes fit into

A

18-40

Optimum 30

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14
Q

Is strep pyogenes positive or negative for catalase production

A

Catalase NEGATIVE

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15
Q

Where does S.salivarius live

A

MOUTH

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16
Q

What does S.agalactiae cause

A

Neonatal meningitis

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17
Q

Name 3 diseases caused by strep pyogenes

A

Tonsillitis, necrotising fasciitis (gangrene) and scarlet fever

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18
Q

What is a key factor of strep classification

A

Their haemolytic properties e,g, alpha, beta or gamma
And SURFACE ANTIGENS E.G. CHO antigens, classifies beta haemolytic strep into specific groups of carbohydrate surface antigen A,B,C,G,F

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19
Q

What enzymes are used in beta haemoyosis to break down our RBC

A

Streptolysin S and O

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20
Q

Who based classification on surface antigens

A

Rebecca lancefield

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21
Q

What strep species partake in partial haemolysis (alpha)

A

S. Pneumoniae and viridians strep

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22
Q

What does hydrogen peroxide produced by the alpha haemolytic species do the haemoglobin

A

Oxidises to green methaemoglobin

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23
Q

Which two species of strep partake in beta haemolysis

A

strep pyogenes and s,agalactiae

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24
Q

What do type II toxin do

Study These Flashcards
A

Attack cholesterol in membrane

25
Which streptolyosin is oxygen labile and which is oxygen stable
Labile - streptolysin O | Stable S - use oxygen
26
Which species partake in gamma haemolysis
Enterococcus
27
Rebecca lancefield identified two major surface antigens that could be used in classification of beta haemolytic strep. What are they?
M proteins | Group Antigen
28
Surface antigen is a carbohydrate antigen incorporated into cell wall by strep. How do we extract it in the laboratory
Mix colony with nitrous acid and this brings the surface antigen away. Also do a variety of agglutination tests using latex beads with antibodies against all group antigens e.g. Group A or B etc
29
How many M proteins are there believed to be
Up to 18
30
What is the group A antigen
NAG - rhamnose. Group A antigen surround cell wall particularly rhamnose
31
What doesnt the antigen classification tell you and how do you resolve this
Species and genus Use API - sugars and enzymes. If does ferment sugar get positive reaction. Add up scores and type into database give this info.
32
What are three things needed to be pathogenic (general)
Colonisation - attachment Evasion Damage via toxins and invasins
33
What do the surface proteins do
Allow colonisation of skin
34
Apart from streptolysins and streptokinase what other enzyme is produced
Hyularonidase
35
What are the toxins that lead to inflammation inducing temp
Streptococcal pyrogenic extoxins (SPE)
36
What does F protein do
Recognise fibronectin on ECM. Primary attachment to pharynx and skin Facilitates internalisation to enter epithelial cells
37
What is gas f protein process
Group A strep bound to f protein This bind to fibronectin and get internalisaed Can be phagocytosis/lysozyme M protein then used to get tighter binding
38
What do M proteins protrude in the form of
Fimbrae and pilli
39
What must M protein go through to extrude as pili
Bound to cytoplasmic membrane, go through peptidoglycan and group antigen (polysaccharide)
40
How many immunological types are there and is reinfectiuon hence common or rare
Excessing 80 types so common reinfection
41
What is distinct about the structure of M proteins
Similar to some of our tissues, heart, kidney, muscle, skin | Risk of autoimmunity
42
What key functions does m protein do
Attachment Bind serum proteases - spread through tissue Antiphagocytuc - prevent c3b binding complement
43
How does it evade our immune system
Hyalurnic acid capsule - we have hyaluronic acd in our ECM so hides. Also bind CD44 which have a lot of in system. Can attach using CD44 Immunolglobulin binding protein - bind to fc region of IgA and IgG preventing opsonisation C5a peptidase - inactivate c5a (reduce neutrophil recruitment)
44
What virulence factors does it secrete
Strep o - MW 60,000. Lysis RBC, pore forming, type II toxin, highly antigenic (produce antibodies to it called streptolyosin o eaters can measure in patients) DNAase - A,B,C,D (b mist common strep) - split DNA use to grow Streptokinase - antigen secreted by strep combine with plasminogen to form plasmin - hydrolyse fibrin clot - spread Hyalurondase - movement SPE's
45
Which virulence factor used clinically and how
Streptokinase - catheter break down clot
46
Where does streptococcal pyrogenic exotoxins bind
Membrane outer
47
What is a superantigen
Antigen get massive cytokine release as doesn't need to be digested and presented on MHC II - non specific binding so many more T cell binding so more TNFa
48
What does immunologically mediated disease mean
Disease due to our antibodies attacking bacteria e.g. Rheumatic fever
49
What are 4 types of disease strep and name infections for each
1- superficial - impetigo, vaginitis 2- deep - septicaemia , gangrene 3- toxin mediated - scarlet fever 4- immuno mediated - rheumatic fever
50
Describe impetigo infection
Initial papulovesicular lesion surrounded by redness Vesicles rapidly become purulent - covered thick honey coloured crust - lesions mostly on face - may resolve within 1-2 weeks but often spread to rest of body Common preschool children, mental institution
51
What is a predisposing factor to impetigo
Bad hygiene
52
What other organism can cause impetigo and what is important vabout infection
Staph | Spread through cough and touch
53
Where does gangrene occur
Subcutaneous tissue (fascia)
54
Describe a gangrene infection
1- initial trauma 2- 48-72hr - skin purple and blisters containing yellow or haemorrhagic fluid appear 3- day 4 - gangrene present - sloughing of skin 4- day 7-10 - skin break down - necrosis subcutaneous tissue. Need surgical debridement to save life
55
Describe first stage of scarlet fever (tonsillitis - strep throat)
Pain, erythema, temp, pus Colonisation followed by inflamed throat ad release of pyrogenic exotoxins (A,B,C,F)
56
Describe scarlet fever
If strep A tonsillitis not treated can get scarlet fever Rash appear 12-72 hrs after fever Spread via coughing, sneezing Children - 5-15 years Symptoms: Sore throat, fever over 38 deg Widespread rash - torso and arms and legs. White strawberry tongue/ red strawberry tongue
57
How many strep throats go to SF
10%
58
Describe the autoimmune disease RF following strep infection
Antibodies produced to GAS M protein and nag cross react human myosin, tropomyosin, laminin and keratin 1-4 weeks post strep infection, associated with M types 1,3,5,6,18,24 Inflammation of joints, heart, CNS, skin
59
Describe other immunologically mediated post strep disease
Glomerulonephritis - affect kidney 3 week post strep assocuiated M types (partiularly) 12, 4,2, 49 Symptoms ; swelling of face, haematuria, fluid balance irregularity Pathogenesis: deposition immune complexes in glomeruli (basement membrane) Cross reacting antibodies to GAS and glomerular antigens

MICROBIOLOGY II (9 decks)

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