Classification of Pathogenic Bacteria 1

Question 1

What are things that can infect patients?

Answer 1

Bacteria

Parasites

Viruses

Fungi

Question 2

What is bacteria?

Answer 2

A major group of microorganisms causing infectious disease

Question 3

What is the process of gram staining?

Answer 3

1) Application of crystal violet (purple dye)
2) Application of iodine (morant)
3) Alcohol wash (decolourisation)
4) Application of safranin (counter stain)

Question 4

What colour does gram positive bacteria appear?

Answer 4

Purple

Question 5

What colour does gram negative bacteria appear?

Answer 5

Pink

Question 6

What does gram staining do?

Answer 6

Provide early indication of the genus of bacteria

Question 7

What are advantages of gram staining?

Answer 7

Quick, simple and inexpensive way to classify bacteria

Question 8

What does knowing the classification of bacteria allow?

Answer 8

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

Question 9

What are the main classes of gram positive bacteria?

Answer 9

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

Anaerobic
Cocci
Bacalli

Question 10

What is cocci bacteria?

Answer 10

Bacteria with a spherical shape

Question 11

What is bacalli bacteria?

Answer 11

Bacteria with a rod shape

Question 12

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

Answer 12

Coagulase positive

Coagulase negative

Question 13

What is coagulase?

Answer 13

An enzyme that convers fibrinogen into fibrin which causes blood clotting

Question 14

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

Answer 14

Coagulase test

Question 15

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

Answer 15

Staphylococci aureus which can cause:

MRSA

MSSA

Question 16

What is staphylococcus commonly resistant to and why?

Answer 16

Penicillin due to production of penicillinase

Question 17

What is MRSA?

Answer 17

Methicillin resistant staph aureus

Question 18

Where is staphylococci a commensal?

Answer 18

In the nose, axilla and perineum

Question 19

What are examples of coagulase negative staphylococci?

Answer 19

Staphylococci epidermis

Staphylococci haemolyticus

Staphylococci saprophyticus

Staphylococci lugdenensis

Question 20

What are coagulase negative staphylococci commonly?

Answer 20

Skin commensals

Question 21

When can coagulase negative staphylococci cause problems?

Answer 21

In the presence of foreign objects such as prosthetic heart valves

Question 22

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

Answer 22

Alpha haemolytic (partial haemolysis)

Beta haemolytic (complete haemolysis)

Non-haemolytic

Question 23

What is haemolysis?

Answer 23

Rupture or destruction of red blood cells

Question 24

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

Answer 24

Streptococci pneumoniae which causes:
Pneumonia
Meningitis
Septicaemia

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

Question 25

What does streptococci pneumoniae cause?

Answer 25

Pneumonia Mengingitis Septicaemia

Question 26

What is infective endocarditis?

Answer 26

Infection of heart valves

Question 27

How can beta haemolytic streptococci further be identified?

Answer 27

By carbohydrate surface antigens ranging from A to G

Question 28

What are the clinical important groups of beta haemolytic bacteria?

Answer 28

Groups A, B, D and F

Question 29

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

Answer 29

Streptococcus pyogenes which causes: Pharyngitis Cellulitis Necrotising fasciltis

Question 30

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

Answer 30

Streptococci agalactiae which causes: Neonatal sepsis (meningitis/bacteraemia) Invasive infections

Question 31

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

Answer 31

Streptococci enterococcus faecalis which causes: Urinary tract infection Infective endocarditis

Question 32

What are some examples of aerobic gram positve bacteria?

Answer 32

Clostridium genus: Clostridium difficile Clostridium perfringens Clostridium tetani

Question 33

Where is clostridium difficile cause found and what does it cause?

Answer 33

In the gut and it causes diarrhoea

Question 34

What is clostridium difficile spread by?

Answer 34

Pores

Question 35

Where is clostridium perfringens found and what can it cause?

Answer 35

Found in soil and a normal commensal in gut faeces, if it infects wounds it can cause gas gangrene

Question 36

What does clostridium cause?

Answer 36

Toxin produced causes tetanus

Question 37

What are examples of biological spore warfare?

Answer 37

Clostridium botulnum (source of botox) Basillus anthracis (cause of anthrax)

Question 38

What is colonisation?

Answer 38

Germs being in the body buyt not making you sick

Question 39

What is infection?

Answer 39

Germs are in the body and making you sick