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1

What are things that can infect patients?

Bacteria

Parasites

Viruses

Fungi

2

What is bacteria?

A major group of microorganisms causing infectious disease

3

What is the process of gram staining?

1) Application of crystal violet (purple dye)

2) Application of iodine (morant)

3) Alcohol wash (decolourisation)

4) Application of safranin (counter stain)

4

What colour does gram positive bacteria appear?

Purple

5

What colour does gram negative bacteria appear?

Pink

6

What does gram staining do?

Provide early indication of the genus of bacteria

7

What are advantages of gram staining?

Quick, simple and inexpensive way to classify bacteria

8

What does knowing the classification of bacteria allow?

Targeted treatment as different classes of antibiotics are effective against gram positive and gram negative bacteria

9

What are the main classes of gram positive bacteria?

Aerobic 
     Cocci
          Chains - streptococci and enterococci
               Alpha, beta or non haemolytic
          Clusters - staphylococci
               Coagulase negative or positive
     Bacalli - small and large

Anaerobic
     Cocci
     Bacalli

10

What is cocci bacteria?

Bacteria with a spherical shape

11

What is bacalli bacteria?

Bacteria with a rod shape

12

What are the two classes of staphylococci (aerobic cocci clusters)?

Coagulase positive

Coagulase negative

13

What is coagulase?

An enzyme that convers fibrinogen into fibrin which causes blood clotting

14

What is used to determine whether bacteria is coagulase positive or negative?

Coagulase test

15

What is an example of coagulase positive staphylococci and what can it cause?

Staphylococci aureus which can cause:

MRSA

MSSA

16

What is staphylococcus commonly resistant to and why?

Penicillin due to production of penicillinase

17

What is MRSA?

Methicillin resistant staph aureus

18

Where is staphylococci a commensal?

In the nose, axilla and perineum

19

What are examples of coagulase negative staphylococci?

Staphylococci epidermis

Staphylococci haemolyticus

Staphylococci saprophyticus

Staphylococci lugdenensis

20

What are coagulase negative staphylococci commonly?

Skin commensals

21

When can coagulase negative staphylococci cause problems?

In the presence of foreign objects such as prosthetic heart valves

22

What classes of bacteria are there in terms of how they degrade blood?

Alpha haemolytic (partial haemolysis)

Beta haemolytic (complete haemolysis)

Non-haemolytic

23

What is haemolysis?

Rupture or destruction of red blood cells

24

What are examples of alpha haemolytic streptococci and what do they cause?

Streptococci pneumoniae which causes:
Pneumonia
Meningitis
Septicaemia

Viridans streptococci which causes:
Infective endocarditis (infection of heart valves)

25

What does streptococci pneumoniae cause?

Pneumonia

Mengingitis

Septicaemia

26

What is infective endocarditis?

Infection of heart valves

27

How can beta haemolytic streptococci further be identified?

By carbohydrate surface antigens ranging from A to G

28

What are the clinical important groups of beta haemolytic bacteria?

Groups A, B, D and F

29

What is an examples of group A beta haemolytic streptococci and what does it cause?

Streptococcus pyogenes which causes:

Pharyngitis

Cellulitis

Necrotising fasciltis

30

What is an example of a group B beta haemolytic streptococci and what does it cause?

Streptococci agalactiae which causes:

Neonatal sepsis (meningitis/bacteraemia)

Invasive infections