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Infection - Alex's Cards (ESA2) > Session 6 Lecture Notes > Flashcards

Session 6 Lecture Notes Flashcards

1
Q

What is a surface (for infection spread?)

A

An interface between a solid and either a liquid or gas

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2
Q

What are the 2 surface types on a patient?

A
  1. Skin

2. Mucosal surfaces

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3
Q

Give some examples of mucosal surfaces in our body

A
  1. Conjunctival (eye)
  2. GI
  3. Respiratory
  4. Genitourinary
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4
Q

What are the viruses that can be found on the skin?

A

Papilloma

Herpes simplex

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5
Q

What gram positive bacteria are found on the skin? List 3 of the most common types

A
  1. Staph aureus
  2. Coagulate negative staphylcocci
  3. Cornyebacterium
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6
Q

Name a gram negative bacteria found on the skin

A

Enterobacteriaceae

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7
Q

What gram positive bacteria is often found in contaminated blood samples?

A

Coagulase negative staphylococci

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8
Q

What causes tonsillitis?

A

Invasion of strep pyrogenes pharyngitis into the tonsils

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9
Q

What gram positive bacteria commonly causes infections around artificial joint surfaces?

A

Coagulase negative staphylococcus

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10
Q

What is a haematogenous spread of infection?

A

Blood borne spread of infection

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11
Q

What gram positive bacteria commonly cause endocarditis?

A

Coagulase negative staphylococcus

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12
Q

Give some examples of prosthetic surface infection locations

A
  1. Peritoneal dialysis catheter
  2. IV lines
  3. Prosthetic joints
  4. Cardiac valves
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13
Q

When might viridans streptococci cause endocarditis ?

A
  1. In a native heart valve

2. In a valve replacement that is less than a year old

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14
Q

When does coagulase negative staphylococci cause endocarditis?

A

In a heart valve replacement that is over a year old

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15
Q

What 2 bacteria commonly cause infections at prosthetic joint surfaces?

A
  1. Coagulase negative staphylococcus

2. Staph aureus

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16
Q

What structures of the bacteria help them to attach and create a biofilm?

A

Pilli

17
Q

What are the 3 principles of biofilm formation?

A
  1. Autoinducers are secreted
  2. These bind to receptors on nearby bacteria
  3. This activates the receptor and causes more release of autoinducers and co-ordinates activity
18
Q

Streptococci is a gram positive or negative bacteria?

A

Gram positive cocci

19
Q

Streptococci can be classified by haemolysis

What are the 3 categories and how do they affect the RBCs on the blood afar plate?

A
  1. Gamma (non-haemolytic) - ie no destruction of RBCs
  2. Alpha haemolysis - partial break down of RBCs
  3. Beta haemolysis - complete break down of RBCs
20
Q

What is the class of streptococci that produce alpha haemolysis?

A

Viridans streptococci

21
Q

Why do viridans streptococci have a wet appearance on a blood agar plate?

A

They have a carbohydrate capsule which makes the organism more virulent

22
Q

What could you expect to see on a blood agar plate of a streptococci that is beta haemolytic?

A

Clear zones where all that is left is the agar (jelly) - as the RBCs have been completed destroyed

23
Q

What does the Lancefield classification of streptococci do?

A

Separate BETA-haemolytic streptococci (fully haemolytic) into groups based upon their cell wall antigens

24
Q

What does the Sherman classification of streptococci do?

A

Separate Streptococci into 4 different classes

  1. Pyogenic (pus forming)
  2. Viridens
  3. Enterococcal
  4. Lactic
25
Q

What Lancefield group is Streptococcus Pyogenes?

A

Group A beta-haemolytic streptococci (completely breaks down RBCs)

26
Q

Streptococcus pyogenes has a number of virulence factors

Name as many as possible

A 
Hyaluronic acid capsule
M Protein
Adhesins
Streptolysins O and S
Dnases A-D
Hyaluronidase and Streptokinase
Streptococcal pyrogenes exotins
27
Q

What does a hyaluronic acid capsule do? (virulence factor of streptococcus pyogenes)

A

Inhibits phagocytosis

28
Q

What does the M protein do? (virulence factor of streptococcus pyogenes)

A

Prevents phagocytosis by inhibiting activation of alternative complement pathway on bacterial cell surface

29
Q

What do adhesins do? (virulence factor of streptococcus pyogenes)
Give a couple of examples

A

Help the bacteria adhere to epithelial surfaces (first step in colonisation/infection)
M proteins and fibronectin binding protein act as adhesins

30
Q

What do Streptolysins O and S do? (virulence factor of streptococcus pyogenes)

A

Lysis of RBCs neutrophils and platelets (cause of haemolysis)

31
Q

What do Dnases A, B, C and D do?

A

When neutrophils approach a bacteria to neutralise it, they condense their DNA (as they are about to self-destruct) and they expel this as a net to help catch the pathogen
Dnases break down DNA so inactivate this method in neutrophils

32
Q

What do streptococcal pyrogenic exotoxins do?

A

They cleave IgG bound to Group A Strep (breaking down the antibody response in the host cell)

33
Q

What bacteria is the common cause of streptococcal pharyngitis?

A

Streptococcus pyogenes (Group A beta haemolytic streptococci - which is a gram positive bacteria)

34
Q

What happens if you don’t treat a patient with streptococcal pharyngitis?

A

The patient will develop an M protein specific antibody but there are some occasional complications such as scarlet fever

35
Q

Name 4 complications from streptococcal pharyngitis

A
  1. Scarlet fever
  2. Suppurative complications (pus forming)
  3. Acute rheumatic fever
  4. Acute post-streptococcal glomerulonephritis
36
Q

What skin infections can streptococcus pyogenes cause?

A
  1. Impetigo
  2. Erysipelas
  3. Cellulitis
  4. Necrotising fasciitis
37
Q

What bacteria/s causes impetigo?

What can impetigo lead to?

A

Streptococcus pyogenes or staph aureus

It can lead to glomeuruonephritis

38
Q

What are the 4 signs of toxic shock syndrome?

A
  1. Deep tissue infection with streptococcus pyogenes
  2. Bacteraemia (bacteria in the blood)
  3. Vascular collapse
  4. Organ failure

Infection - Alex's Cards (ESA2) (8 decks)

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