Infection Session 9 Flashcards
How can chronic diseases be acquired?
VITMAMIN DEI Vascular Infective Trauma Autoimmune Metabolic Inflammatory Neurological/neoplasia Degenerative Environmental Idiopathic
What is the most common gene mutation inherited by cyctic fibrosis patients?
Delta F508 (deletion of phenylalanine at position 508)
Why do CF patients require close nutritional monitoring?
Good nutrition must be maintained otherwise malnutrition due to impaired pancreatic function predisposes to infection
What is bronchiectasis?
Widening of bronchi and bronchioles
What causes bronchiectasis in CF?
Dehydrated, thick mucus which blocks small ducts
What is the procession of different organisms that cause pneumonia in CF pts?
H.influenzae (v.early in children)–> staph aureus –> pseudomonas aeruginosa/burkholderia cepacia –> atypical mycobacteria, candida albicans, aspergillus fumigatus
What two types of congenital chronic disease are there?
Genetic
Developmental
Why is lung exercise in CF pts important in reference to infection?
Reduces risk of Pseudomonas aeruginosa and Burkholderia cepacia colonisation
Why is contact between Cf pts kept to a minimum?
Pseudomonas aeruginosa and Burkholderia cepacia can be transmitted person to person
What does the higher frequency of CF gene carriage in the UK population in comparison to other populations suggest?
Balanced polymorphism
What is balanced polymorphism?
2 different versions of one gene are maintained in the population as this confers better survival than 2 copies of either gene alone
What in-vitro interactions w/ CFTR proteins suggest carrying a CF gene confers resistance to cholera, typhoid or TB?
Cholera toxin
Salmonella typhi intracellular entry
What is the pathogenesis of COPD?
Acquired/genetic cause –> inhalation of steroids –> neutrophils and macrophages cause chronic inflammatory response –> free radical production and damage to cilia –> breakdown of lung tissue, small airways disease and increased mucus production
How do acute exacerbations of COPD present?
Sudden episode of excess coughing
Colour change in sputum of white-grey to yellow-green
What are common bacterial causes of COPD exacerbation?
H.influenzae
Ps.aeruginosa
What are common viral causes of COPD exacerbation?
RSV
Rhinovirus
Parainfluenza
Why is evidence of a viral infection more definitive than bacterial?
No risk of sample contamination by RT commensals
What effects do hyperglycaemia and acidaemia in diabetes have on humoral and cellular immunity?
Impair humoral –> decrease ability to produce antibodies
Impair polymorphonuclear leukocyte and lymphocyte functions
What is the pathogensis of vascular implications leading to infection in diabetes?
Diabetic micro- and microvascular disease –> poor tissue perfusion –> increased risk of peripheral BV disease and increased risk of infection
How does diabetic neuropathy lead to infections in diabetic pts?
Decreased skin sensation allowing unnoticed skin breaks to form ulcers and can lead to osteomyelitis
Neurogenic bladder causes incomplete bladder emptying
Which ENT infection is only seen I diabetic pts?
Pseudomonas aeruginosa infection causing malignant/necrotising otitis externa
What is the pathogenesis of malignant/necrotising otitis externa?
Pseudomonas aeruginosa in external auditory canal spreads to adjacent tissues –> ear pain and otorrhoea
What colonises the nose and paranasal sinuses of poorly controlled diabetics?
Mould fungi
What is rhinocerebral mucormycosis, seen in DKA pts?
Nasal fungi spread to adjacent tissues by invading BV –> soft tissue necrosis and bony erosion
What leads to diabetic foot ulcers and necrotising fasciitis in diabetic pts?
Sensory neuropathy+atherosclerotic vascular disease+hyperglycaemia
Give some examples of CNS diseases that affect bladder control.
Alzheimer's Birth defects of spinal cord Cerebral palsy Encephalitis Learning disabilities MS Parkinson's Spinal cord injury Stroke
Give some examples of PNS diseases that can affect bladder control.
Neuropathy Long term heavy alcohol use Long term diabetes Vit B12 deficiency Syphilis Pelvic surgery Herniated disc/spinal cord stenosis
Is there a link between Down’s syndrome and infection risk?
Yes, seems to be elevated as bacterial and viral RTIs seem to be more common in young people w/Down’s syndrome but no well proven and no explanation
What laboratory observations of humoral immunity are seen in a Down’s syndrome pt?
Decreased neutrophil and monocyte function but normal number
Decreased IgG in infants and raised in adults
Decreased specific antibody response on immunisation (still respond clinically if otherwise healthy)
What laboratory observations have been made in pts with Down’s syndrome of their cellular immunity?
Altered T cell distribution but normal T cell
Decreased T cell function
Altered T cell intracellular signalling
Abnormal cytokine production
Decrease of some NK functions but increase in number of NK cells
