Chronic Health And Infections Flashcards
How do chronic conditions make someone more susceptible to infections?
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
Why are CF patients more susceptible to infection?
Thick mucus blocks the small ducts in their lungs because it cannot be shifted out as easily.
What infections are CF patients more susceptible to?
Pseudomonas aeruginosa
Burkholderia cepacia
Aspergillus fumigatus
Classify Pseudomonas aeruginosa
Motile
Anaerobic
Gram negative
What are the consequences of an infection with Pseudomonas aeruginosa in CF patients?
Progressive deterioration in lung function
Very difficult to get rid of in CF patients
What does Pseudomonas aeruginosa do?
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
How does Burkholderia cepacia spread?
From person to person in CF clinics
What does Aspergillus fumigatus do?
Causes worsening of airway inflammation and progressive damage in CF patients
How is Aspergillus fumigatus managed?
Bronchodilators
Steroids
What is COPD (generally)?
Chronic inflammatory response to inhaled irritants, primarily mediated by neutrophils and macrophages.
Causes increased mucus production
Why does poorly controlled diabetes make patients more susceptible to infection?
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
What ENT infections are diabetics more susceptible to? Causative organisms?
Malignant or necrotising otitis externa - Pseudomonas aeruginosa
Rhinocerebral mucormycosis - mould fungi eg Aspergillus
What happens in malignant otitis externa?
Begins in external auditory ear canal and spreads to adjacent soft tissue, cartilage and bone
Typically present with ear pain and otorrhoea (ear discharge)
What is rhinocerebral mucormycosis?
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
Why are diabetics more susceptible to UTIs?
Have a neurogenic bladder from diabetic neuropathy causing defects in bladder emptying
What are UTIs commonly caused by?
E. coli
Pseudomonas aeruginosa
What makes diabetics at increased risk of skin and soft tissue infection?
Sensory neuropathy, atherosclerosis vascular disease and hyperglycaemia
What are some causative organisms of skin/soft tissue infection?
Staph aureus - cellulitis
Group A β-haemolytic streptococci (cellulitis)
Poly microbial including Staph aureus, β-haemolytic Strep, Enterobacteriaceae, anaerobes
What are some examples of skin/soft tissue infection?
Cellulitis
Diabetic foot ulcers
Necrotising fasciitis
What are people with Down’s syndrome more susceptible to?
Respiratory tract infections
Why are people with Down’s syndrome more susceptible to infections?
Possibly immunodeficiency, altered mucus secretions
What is the acute primary infection and recurrence infection of Varicella zoster?
Chicken pox
Shingles
How is varicella zoster spread?
Rupture of the vesicle releases varicella zoster
What is the incubation period of VZV?
14-21 days
When is VZV infectious?
A few days before the rash appears until vesicle fluid has dispersed
How do you get shingles?
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
If immunocompromised patients are infected with Varicella zoster, what are they more at risk of?
Pneumonia
Disseminated disease with visceral involvement
Is Staph aureus coagulase negative or positive?
Coagulase positive
Where is Staph aureus normally found in healthy people?
Nose
Skin
Axilla
Perineum
What is the pathogensis of Staph aureus
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
What infections can Staph aureus commonly cause?
Skin infections Pneumonia Endocarditis Osteomyelitis Septic arthritis
When can Staph aureus cause skin infections?
Warm, moist conditions
When skin is broken by disease eg eczema, surgical wounds, IV devices
Impetigo in healthy skin
What does Staph aureus pneumonia normally follow?
Influenza
Progresses rapidly
Cavity formation
High mortality
What can Staph aureus endocarditis commonly follow?
IV drug misuse
Colonisation of IV a devices
