Lecture 2 GP Bacteria Again but More

Question 1

Do Steptococci test positive or negative for the catalase test?

Answer 1

Negative

Question 2

What kind aerobe is steptococci?

Answer 2

Facultatively anaerobic

Question 3

Is Streptococci Gram positive or Gram negative?

Answer 3

Gram Positive

Question 4

How is Streptococci found?

Answer 4

In pairs and chains

Question 5

What are the 5 ways to tell apart different Streptococci?

Answer 5

Overlapping schemes
Serology- Reactions of antibodies to specific bacterial antigens
Haemolysis- Beta haemolytic streptococci
Cell arrangement
Physiological- Biochemical tests

Question 6

What are the 3 types of Haemolysis present in Streptococci?

Answer 6

Alpha
Beta
Gamma

Question 7

Which strains show beta haemolysis?

Answer 7

Mainly Lancefield groups, strep.pyogenes, strep. agalactiae

Question 8

Which strains show alpha haemolysis?

Answer 8

Strep.pneumoniae and viridans streptococci

Question 9

Which stains show gamma haemolysis?

Answer 9

Enterococci.

Question 10

What should you see if a bacteria shows gamma haemolysis?

Answer 10

Nothing.

Question 11

What is Lancefield Grouping?

Answer 11

A type of serological classification scheme, used to classify catalase-negative gram positive cocci based on the carbohydrate composition of bacterial antigens found on their cells walls.

Question 12

Why do we use horse blood for blood agar?

Answer 12

Allows the detection of Haemolytic reactions
Contains X factory and V factory needed for the growth of many bacterial species e/g haemophilus influenzae

Question 13

What groups contain the more significant human pathogens in the Lancefield groups?

Answer 13

A-G but not E

Question 14

What is another name for Group A Streptococcus?

Answer 14

GAS or S.pyogenes

Question 15

What are the 4 characteristics of Group A Streptococcus/S.pyogenes?

Answer 15

Forms 1-2mm white colonies
Large zone of beta haemolysis on blood agar
Bacitracin sensitive
Pathogenic species often capsulated

Question 16

What does Protein M do (found in Strep A)?

Answer 16

A membrane protein, it destabilises complement interfering with opsonisation and lysis

Question 17

How does Strep A use hyaluronic acid?

Answer 17

Hyaluronic acid forms a capsule that can camouflage the bacteria against WBCs

Question 18

What is the use of the Streptolysins created by Strep A?

Answer 18

Breaks down RBCs, WBCs and platelets.

Interferes with oxygen carrying capacity of RBC, immunity and blood clotting

Question 19

What happens to the WBC if it eats a Strep A that has produced 2 membrane bound proteins?

Answer 19

After being phagocytised, streptolysins are released into the cytoplasm of the phagocyte.
This causes the cell to release its lysosomes, breaking down the phagocyte, releasing more bacteria.

Question 20

What is the purpose of the 2 Streptokinases that Strep A has?

Answer 20

Breaks down blood clot, thus enables rapid spread through infected and damaged tissue

Question 21

Name the 4 enzymes that Strep A produces?

Answer 21

Streptokinases (2)
Distinct deoxyribonucleases (4)
C5a peptidase
Hyaluronidase

Question 22

What is the purpose of the 4 distinct deoxyribonucleases that Strep A produces?

Answer 22

Depolymerise DNA released from dead cells in abscesses
This reduces firmness of pus and increase rate of spread.

Question 23

What does the enzyme C5a peptidase do?

Answer 23

Breaks down C5a complement protein
Acts as a chemotactic factor
Decreases movement of WBCs into infection site

Question 24

What does the enzyme Hyaluronidase do?

Answer 24

Breaks down hyaluronic acid
This increases the spread of Strep A through the tissues

Question 25

How many pyrogenic toxins are there?

Answer 25

3

Question 26

Explain what pyrogenic toxins can do

Answer 26

Stimulates macrophage and T helper lymphocytes Causes the release of cytokines This causes fever, rash and shock

Question 27

Where are toxin genes carried?

Answer 27

Found on temperate phages (only lysogenised bacteria can secrete)

Question 28

Which two genera of bacteria can produce pyrogenic toxins?

Answer 28

Staphylococcus and Streptococcus

Question 29

If 1 bacteria goes into the lytic/lysogenic cycle, how many come out?

Answer 29

200

Question 30

Where does Streptococci like to infect?

Answer 30

Pharynx or skin (resulting in temporary abscesses) Can invade deeper into tissues and organs through barrier breaks

Question 31

Why does Streptococci cause temporary abscesses?

Answer 31

M proteins and streptolysins produced by Strep cause a specific immune response to occur

Question 32

What does GAS do to the gut microbiome?

Answer 32

GAS will compete with your microbiota until its all depleted. Large numbers can easily take over the gut microbiome before antibodies are formed. Immunocompromised patients would not survive this.

Question 33

How is Strep transmitted?

Answer 33

Normally through respiratory droplets, helps if its crowded

Question 34

List the 7 things that GAS can cause?

Answer 34

Pharyngitis Scarlet fever Pyoderma and Erysipelas Streptococcal Toxic Shock Syndrome Necrotizing fasciitis Rheumatic fever Glomerulonephritis

Question 35

What does the ASOT/ASLO blood test do?

Answer 35

Looks for antibodies to the Strep A bacteria. If abnormal results or positive then it shows that you have recently had a strep infection even with no symptoms

Question 36

What 3 antibiotics can you give if someone has a Strep A infection?

Answer 36

Penicillin Erythromycin Cephalexin

Question 37

What is another name for Strep B?

Answer 37

S.agalactiase

Question 38

The 4 stats of Strep B

Answer 38

Bacitracin resistant Produces capsules (doesn't protect from antibodies) Predilection for newborns Produces proteases and haemolysins

Question 39

What are the two enzymes that Strep B produces?

Answer 39

Proteases and haemolysins

Question 40

Where does Strep B like to infect?

Answer 40

Lower GI tract Genitals Urinary tract

Question 41

What is the morality rate of Strep B?

Answer 41

Over 50%

Question 42

What does GAS mean?

Answer 42

Group A Strep

Question 43

How is Group B Strep treated?

Answer 43

Penicillin Sometimes streptomycin as some Group B Streps can tolerate a Pen conc x10

Question 44

How is Group B Strep treated in newborns?

Answer 44

Prophylaxis

Question 45

Is vaccination viable against Group B Strep?

Answer 45

Vaccinations would be nice if we had any :/

Question 46

Name the two other beta haemolytic streptococci

Answer 46

S.equisimilis S.anginosus

Question 47

What does S.equisimilis cause?

Answer 47

Pharyngitis

Question 48

What does S.anginosus cause?

Answer 48

Purulent abscesses

Question 49

Where is Viridans Streptococci found?

Answer 49

Mouth (apart of our gut flora) Pharynx GI tract Urinary Tract (of humans)

Question 50

What symptoms can Viridans Streptococci cause?

Answer 50

Purulent abdominal infections Dental caries (dextran) Biofilm (dental plaque) Meningitis (if gets into blood) Endocarditis

Question 51

What is Strep Pneumoniae sensitive to?

Answer 51

Optochin

Question 52

What type of haemolysis does Strep Pneumoniae do?

Answer 52

Alpha

Question 53

What does Strep Pneumoniae look like on blood agar?

Answer 53

Dimpled colony due to death of older cells

Question 54

Where can you find Strep Pneumoniae?

Answer 54

Normal flora of the pharynx Can colonise the lungs, sinuses and middle ear

Question 55

What causes virulence in Strep Pneumoniae?

Answer 55

Polysaccaride capsule Unencapsulated strains are avirulent

Question 56

What does Strep Pneumoniae produce?

Answer 56

Produces phosphorylecholine

Question 57

What does phosphorylecholine do?

Answer 57

Stimulates cell receptors within the lungs/meninges/blood vessels to engulf and hide itself (Strep Pneumoniae)

Question 58

What does IgA do?

Answer 58

Can limit migration of bacteria into the lungs. By binding to the organism and then binding to the mucous so that it can be swept up and away from the ciliated epithelium

Question 59

What is a countermeasure the pathogen can do against IgA?

Answer 59

Produces IgA protease.

Question 60

What is Pneumolysin?

Answer 60

A type of pore-forming toxin (can create small holes/pores in host cell cell membrane)

Question 61

Which bacteria produces pneumolysin?

Answer 61

Streptococcus pneumoniae

Question 62

Where does Streptococcus pneumoniae infect?

Answer 62

Causes lung infections

Question 63

What demographic does Streptococcus pneumoniae affect the most?

Answer 63

The young and elderly because their immune systems are not fully active

Question 64

List the 6 diseases that can be caused by an infection of Streptococcus pneumoniae

Answer 64

Pneumonia Sinusitis Otitis media Bacteremia Endocarditis Meningitis (affects children more because they haven't been vaccinated yet)

Question 65

How is Strep Pneumoniae treated?

Answer 65

Penicillin

Question 66

Why can't we use Cephalosporin, Erythromycin and Chloramphenicol to treat Strep Pneumoniae?

Answer 66

1/3 of Strep Pneumoniae are resistant

Question 67

Is there a vaccine for Strep Pneumoniae?

Answer 67

Yes, against the 23 most common pneumococcal strains

Question 68

Name 5 other gram positive bacteria

Answer 68

Enterococci Bacillus sp Listeria Corynebacteria Mycobacteria