Chronic Health And Infections

Question 0

How do chronic conditions make someone more susceptible to infections?

Answer 0

They change the structure or function of the affected tissues/organs which has a potential for changing the interaction between the patient and microorganisms.
Can also be affected by consequences of treatment eg steroids, antibiotics

Question 1

Why are CF patients more susceptible to infection?

Answer 1

Thick mucus blocks the small ducts in their lungs because it cannot be shifted out as easily.

Question 2

What infections are CF patients more susceptible to?

Answer 2

Pseudomonas aeruginosa
Burkholderia cepacia
Aspergillus fumigatus

Question 3

Classify Pseudomonas aeruginosa

Answer 3

Motile
Anaerobic
Gram negative

Question 4

What are the consequences of an infection with Pseudomonas aeruginosa in CF patients?

Answer 4

Progressive deterioration in lung function

Very difficult to get rid of in CF patients

Question 5

What does Pseudomonas aeruginosa do?

Answer 5

Produces cytotoxic proteases
In CF patients, produces extracellular mucopolysaccharide (biofilm) which allows micro-colonies to form where organisms are protected from opsonisation, phagocytosis and antibiotics

Question 6

How does Burkholderia cepacia spread?

Answer 6

From person to person in CF clinics

Question 7

What does Aspergillus fumigatus do?

Answer 7

Causes worsening of airway inflammation and progressive damage in CF patients

Question 8

How is Aspergillus fumigatus managed?

Answer 8

Bronchodilators

Steroids

Question 9

What is COPD (generally)?

Answer 9

Chronic inflammatory response to inhaled irritants, primarily mediated by neutrophils and macrophages.
Causes increased mucus production

Question 10

Why does poorly controlled diabetes make patients more susceptible to infection?

Answer 10

Hyperglycaemia and acidaemia impair

• humoral immunity
• polymorphonuclear leukocyte and lymphocyte functions

Diabetic micro/macrovasculature cause poor tissue perfusion and increased risk of infection

Diabetic neuropathy causes diminished sensation resulting in unnoticed skin injuries

Question 11

What ENT infections are diabetics more susceptible to? Causative organisms?

Answer 11

Malignant or necrotising otitis externa - Pseudomonas aeruginosa
Rhinocerebral mucormycosis - mould fungi eg Aspergillus

Question 12

What happens in malignant otitis externa?

Answer 12

Begins in external auditory ear canal and spreads to adjacent soft tissue, cartilage and bone
Typically present with ear pain and otorrhoea (ear discharge)

Question 13

What is rhinocerebral mucormycosis?

Answer 13

Fungi colonise nose and paranasal sinuses
Spread to adjacent tissues by invading blood vessels and causing soft tissue necrosis and bony erosion
Can be fatal

Question 14

Why are diabetics more susceptible to UTIs?

Answer 14

Have a neurogenic bladder from diabetic neuropathy causing defects in bladder emptying

Question 15

What are UTIs commonly caused by?

Answer 15

E. coli

Pseudomonas aeruginosa

Question 16

What makes diabetics at increased risk of skin and soft tissue infection?

Answer 16

Sensory neuropathy, atherosclerosis vascular disease and hyperglycaemia

Question 17

What are some causative organisms of skin/soft tissue infection?

Answer 17

Staph aureus - cellulitis
Group A β-haemolytic streptococci (cellulitis)

Poly microbial including Staph aureus, β-haemolytic Strep, Enterobacteriaceae, anaerobes

Question 18

What are some examples of skin/soft tissue infection?

Answer 18

Cellulitis
Diabetic foot ulcers
Necrotising fasciitis

Question 19

What are people with Down’s syndrome more susceptible to?

Answer 19

Respiratory tract infections

Question 20

Why are people with Down’s syndrome more susceptible to infections?

Answer 20

Possibly immunodeficiency, altered mucus secretions

Question 21

What is the acute primary infection and recurrence infection of Varicella zoster?

Answer 21

Chicken pox

Shingles

Question 22

How is varicella zoster spread?

Answer 22

Rupture of the vesicle releases varicella zoster

Question 23

What is the incubation period of VZV?

Answer 23

14-21 days

Question 24

When is VZV infectious?

Answer 24

A few days before the rash appears until vesicle fluid has dispersed

Question 25

How do you get shingles?

Answer 25

Infected with VZV
Lies latent in posterior root ganglion
In 20% of those previously infected, will travel down the axon and produce reactivation lesions in that dermatome causing shingles
Painful

Question 26

If immunocompromised patients are infected with Varicella zoster, what are they more at risk of?

Answer 26

Pneumonia

Disseminated disease with visceral involvement

Question 27

Is Staph aureus coagulase negative or positive?

Answer 27

Coagulase positive

Question 28

Where is Staph aureus normally found in healthy people?

Answer 28

Nose
Skin
Axilla
Perineum

Question 29

What is the pathogensis of Staph aureus

Answer 29

Coagulase converts fibrinogen to fibrin which helps it to form a protective barricade
Receptors for host cell surface and matrix proteins help it to adhere
Produce extracellular lytic enzymes which break down host tissue and aid invasion
Some strains produce endotoxin which can cause toxic shock syndrome
Can produce enterotoxins causing diarrhoea

Question 30

What infections can Staph aureus commonly cause?

Answer 30

Skin infections 
Pneumonia
Endocarditis 
Osteomyelitis
Septic arthritis

Question 31

When can Staph aureus cause skin infections?

Answer 31

Warm, moist conditions
When skin is broken by disease eg eczema, surgical wounds, IV devices
Impetigo in healthy skin

Question 32

What does Staph aureus pneumonia normally follow?

Answer 32

Influenza
Progresses rapidly
Cavity formation
High mortality

Question 33

What can Staph aureus endocarditis commonly follow?

Answer 33

IV drug misuse

Colonisation of IV a devices