2.1 - Infection Model

Question 1

Different types of pathogen

Answer 1

• virus these are acellular
• prokaryotes bacterium
• eukaryotes fungi + parasite
• Parasites = protozoa (single celled) and helminth (worm, multicellular)
• Fungi = yeast (single celled) and mould (multicellular)

Question 2

How do patients vary (examples of different factors)

Answer 2

• age susceptibility, exposure and response to infection varies with age
• gender due to physiological + anatomical differences
• physiological state eg pregnancy
• pathological state underlying conditions eg stroke, diabetes, swallowing defects
• social factors such as socioeconomic status, deprived areas

☞ calendar time so in winter, more likely to see more respiratory infections
☞ relative time since being exposed to infected person/pathogen

Question 3

Different mechanisms of infection

Answer 3

• contiguous (direct) ie direct trauma to skin + infected with bacteria from skin
• inoculation eg thorn going into skin, such as tetnus
• haematogenous blood borne spread
• ingestion eating or drinking something
• inhalation breathing something in
• vector eg mosquito transmission
• vertical transmission from mother to child during pregnancy or delivery

Question 4

What are the different factors that affect infection

Answer 4

• attachment where the bacteria sticks to something (ie spike protein) either intracellularly or extracellularly
• toxin production as some bacteria can produce toxins that directly damage host tissues
• inflammation can be systemic or localised. This can be damaging in itself (eg meningitis) – need to give antibiotics
• These factors can affect host damage

Question 5

Specific vs supportive treatment

Answer 5

specific
Aimed at treating the underlying disease, such as giving antibiotics

supportive
Aimed at relieving patient’s discomfort, such as giving analgesics

Question 6

How can surgery help treat infections

Answer 6

☞ drainage of infected fluid, and to stop it building up in cavities ie peritonitis
☞ debridement eg in endocarditis (infection of heart valves or associated tissue) – need to remove infected valve
☞ dead space removal (after removing infected bone + surrounding muscle) → need to get rid of gap to ensure that it doesn’t allow fluid to accumulate