Exercise 3: Handwashing - How effective can it be?

Question 1

Explain the term resident flora

Answer 1

• The microorganisms which are consistently found at a given site and multiply there
• These are essential to the healthy functioning of the organs involved and form part of our defences against infection

Question 2

Explain the term transient flora

Answer 2

• Microorganisms that are temporarily found at a given site but do not multiply there
• These species are acquired by contact with the surrounding environment, and many are pathogens

Question 3

Explain the term nosocomial infections

Answer 3

Infections acquired in a hospital (Hospital-acquired infections)

Question 4

Explain the term opportunistic pathogen and give an example

Answer 4

• Opportunistic pathogens are those that normally constitute a part of the normal resident flora, but under certain circumstances (eg weakened immune system, an altered microbiota) they become pathogenic
• Escherichia coli is a part of the normal resident flora of the bowel, but is a common pathogen of the urinary tract

Question 5

Where in the human body does Staphylococcus aureus generally colonise? Describe the different types of carriers

Answer 5

• The ecological niches of S. aureus strains are the anterior nares
• 30% of humans are asymptomatic nasal carriers of S. aureus

Incidence of S. aureus can be placed in 3 categories:

• Persistent carriers (20% of population) - carry one type of strain
• Intermittent carriers (60%) - harbour S. aureus intermittently (strains change with varying frequency)
• Non-carriers (20%) - never carry S. aureus

Question 6

Rank Soap, Bioprep, and Commercial sanitizer in order of effectiveness at removing flora from the hands

Answer 6

1. Bioprep
2. Soap
3. Commercial sanitizer (eg Dettol)

Question 7

What happens to the flora of your hands when you wash them?

Answer 7

In unwashed hands there are both transient and resident flora, whereas in washed hands the resident flora is present while the transient flora is washed off.