I: Infections On Surfaces

Question 1

Name 2 surfaces naturally present in a patient that micro-organisms will colonise on and give examples for each.

Answer 1

1. Skin: (Epithelium, hair, nails)

2. Mucous Surfaces: (conjunctival, gastrointestinal, respiratory, genitourinary)

Question 2

What is the importance of microbiota?

Answer 2

Creates competition for my harmful organisms, hence preventing their proliferation.

Question 3

Name 4 ways in which a patient can get infections from themselves.

Answer 3

1. Invasion
2. Migration
3. Inoculation
4. Haematogenous

Question 4

Give some examples of natural external surface infections.

Answer 4

1. Cellulitis
2. Pharyngitis
3. Conjunctivitis
4. UTI
5. Pneumonia

Question 5

Give some examples of internal natural surface infections.

Answer 5

1. Endocarditis
2. Vasculitis
3. Septic arthritis

Question 6

Give some examples of prosthetic surface infections.

Answer 6

1. IV lines
2. Catheters
3. Prosthetic joints
4. Cardiac valves
5. Pacing wires
6. Ventricular-peritoneal shunts

Question 7

Name the organisms that can be responsible for prosthetic valve endocarditis.

Answer 7

> 1 year: viridans streptococci

<1 year: coagulase negative staphylococci

Question 8

Name the causative organisms of prosthetic joint infections.

Answer 8

• Coagulase negative staphylococci

- Staphylococcus aureus

Question 9

Name the causative organisms of cardiac pacing wire endocarditis.

Answer 9

• Coagulate negative staphylococci

- Staphylococci aureus

Question 10

Describe the process of pathogenesis of a surface infection.

Answer 10

• Adherence to host cell/ prosthetic surface
• Biofilm formation
• Invasion and multiplication
• Host response

Question 11

Describe how surface infections are managed after an infection has colonised.

Answer 11

• Identity the causative organisms and give the appropriate antibiotics to which it will be susceptible
• Remove infected prosthetic
• Surgery: cut out infected area

Question 12

Describe how surface infections are managed before an infection has colonised.

Answer 12

Natural Surface: maintain structure integrity, prevent bacterial colonisation

Prosthetic Surface: Silver lined tubes, good surgical prep

Question 13

What is biofilm?

Answer 13

Thin layer of slime which is contains communities of bacteria.

Question 14

What is the clinical importance of biofilm?

Answer 14

It is difficult for antibiotics to penetrate and therefore to kill the bacteria.