Session 6 - Infections on Surfaces

Question 1

What is a surface?

Answer 1

Interface between a solid and either a liquid or gas.

Question 2

What are some nautral surfaces that can carry infections?

Answer 2

Surfaces on the human body:

• Skin
  
  • epithelium
  • hair
  • nails
• Mucosal surfaces
  
  • conjunctival
  • gastrointestinal
  • respiratory
  • genitourinary

Question 3

What are some microorganisms that live on the skin?

Answer 3

• Human Papilloma Virus
• Herpes simplex
• Staphylococcus aureus
• Enterobacteriaceae
• Yeasts

Question 4

What are some mucosal flora present on the eye?

Answer 4

• Coagulase negative staphylococci
• Neiserria species

Question 5

What are some muscosal flora present in the nares and nasopharynx?

Answer 5

• Staphylococcus aureus
• Neisseria meningitidis
• Streptococcus pneumoniae
• Haemophilus influenzae

Question 6

What are some mucosal flora present in the mouth?

Answer 6

• Neisseria
• Lactobacillus
• Candida

Question 7

What are some mucosal flora present in the stomach?

Answer 7

• Streptococci
• Staphylococci

Question 8

What are some mucosal flora present in the intestine?

Answer 8

• Lactobacillus
• Aerobic and anaerobic streptococci
• Clostridium
• Yeasts

Question 9

What are some mucosal flora present in the urethra?

Answer 9

• Enterobacteriacaea
• Lactobacilli
• Alpha and non-haemolytic streptococci
• Enterococci

Question 10

What are some mucosal flora present in the vagina?

Answer 10

• Lactobacilli
• Micrococci
• Yeasts
• Enterococcus faecali

Question 11

What is the purpose of microorganisms on skin and mucosal surfaces?

Answer 11

• Normally harmless and can be beneficial
• They take up space and nutrients, making it more difficult for malignant pathogens to grow on the skin

Question 12

How do people get infections from normal flora?

Answer 12

Invasion:

• Streptococcus pyogenes causing pharyngitis

Migration:

• E. coli causing UTI

Innoculation:

• coagulase negative staphylococcus causing prosthetic joint infection

Haematogenous (gets into the blood)

• viridans streptococcus endocarditis

Question 13

What are some examples of external nautral surface infections?

Answer 13

• Cellulitis
• Pharyngitis
• Conjunctivis
• Gastroenteritis
• UTI
• Pneumonia

Question 14

What are some examples of internal natural surface infections?

Answer 14

• Endovascular
  
  • Endocarditis
  • Vasculitis
• Septic arthritis
• Osteomyelitis
• Empyema (collection of pus in a cavity i.e. pleural cavity)

Question 15

What are some examples of prosthetic surface infections?

Answer 15

• Intravascular lines
• Periotneal dialysis catheters
• Prosthetic joints
• Cardiac valves
• Pacing wires
• Endovascular grafts
• Ventriculo-peritoneal shunts

Question 16

What is the process of pathogenesis of infection at surfaces?

Answer 16

• Adherence to host cells or prosthetic surface
• Formation of a biofilm
• Invasion and multiplication
• Host response (normal infection response)

Question 17

What is a biofilm?

Answer 17

A thin but strong layer of slime-like substance that adheres to a solid surface. Biofilms also contain a community of bacteria and other microorganisms.

Question 18

What is the importance of a biofilm?

Answer 18

It allows for bacteria to grow on either a natural or prosthetic surface.

This makes it easier for a bacteria to spread from a surface to a host, leading to an infection.

Question 19

How can infections on natural surfaces be prevented?

Answer 19

• Maintain surface integrity
• Prevent bacterial surface colonisation
• Remove colonising bacteria

Question 20

How can infections on prosthetic surfaces be prevented?

Answer 20

• Prevent contamination
• Inhibit surface colonisation
• Remove colonising bacteria