Chronic Disease and Infection Flashcards
What is chronic disease and how does infection and microorganisms come into it?
Chronic disease causes a change in the structure of affected tissue/organ which may have the potential for changing the interaction between the patients and micro-organisms.
This may be subsequently and further affected by changes caused by the altered presence of micro-organisms and the consequences of treatment e.g. with antibiotics and steroids.
What is Cystic fibrosis?
Autosomal recessive. Pathogenesis of CF – defect in cystic fibrosis transmembrane conductance regulator gene in exocrine glands. There are a range of different mutations causing it but most frequently it is the Delta F508 by deletion of phenylalanine.
This causes a defect in the CFTR leads to defects in Cl- transmembrane transport. As a result this mucus becomes dehydrated and thick causing blockage in small ducts. It also causes the mucociliary escalator to not work properly.
What organisms (in order) are CF patients at a higher risk of?
- H-Influenzae – Gram negative, normal flora of upper airways and is normally removed by the mucociliary escalator
- Staph Aureus – Gram positive coccus
- Pseudomonas aeruginosa – Gram negative, inherently resistant. Can get different strains mucoid and nonmucoid, CF patients are normally colonised by mucoid strains
- Burkholderia cepacia – Gram negative, even more resistant
- Atypical Mycobacteria – anything that is mycobacterium TB, not usually pathogenic apart from for people with abnormal lung structure. These are hard to culture unless you specifically look for it
- Candida albicans
- Asperigillus fumigatus – slow growing hard to culture and again hard to culture unless you specifically look for it.
How do we try to prevent these lung colonisations from person to person?
CF patients are isolated from other CF patients and the rest of the hospital population to prevent them being given life threatening infections.
How do we treat CF patients to help prevent lung colonisations?
Patients are encouraged to cough up their sputum with the help of physiotherapists and as well as this are given an enzyme called pancrease which helps them to digest their food (pancreatic duct becomes blocked with mucus in CF) this allows them to grow and so their airways get bigger (4th power of radius) and improve their immune system.
What advantages does being heterozygous for CF have?
It is thought being heterozygous for the CF gene can provide resistance to cholera, typhoid or TB
What are the main pathologies and their causes in COPD?
Increased mucus production, breakdown of lung tissue (emphysema) and small airways (obstructive bronchiolitis). Phagocytes cause collateral damage as they attempt to kill pathogenic material or cells.
What is an acute exacerbation of COPD and why does this occur?
Acute exacerbation of COPD – increased number of neutrophils causing green thick mucus due to an acute infection. This occurs much more often because in COPD their mucociliary escalators aren’t functioning properly. Normally we constantly aspirate microbes from our normal flora of our airways and oesophagus however as COPD patients can’t expel those that are caught in the mucus they develop a colonisation.
List some bacterial causes of acute exacerbations in COPD?
- S. Pneumoniae
- Hi Influenzae
- Moraxella Catarrhalis
- Ps Aeruginosa
- E Coli
List some viral causes of acute exacerbatios in COPD?
- Respiratory Syncytial Virus
- Rhinovirus
- Parainfluenza Virus
- Human Metapneumovirus
- Coronavirus – 50% mortality
- Adenovirus
- Influenza A virus
What aspect of the humeral immune system does diabetes affect
Hyperglycaemia and acidaemia impair – humoral immunity, polymorphonuclear leukocytes and lymphocyte functions.
How does diabetes decrease the immune function of the body?
Diabetic microvascular and macrovascular disease result in poor tissue perfusion and increased risk of infection. Diabetic neuropathy causes diminished sensation resulting in unnoticed skin problems.
Describe common ENT infection in diabetic patients
Malignant or necrotising otitis externa. Pseudomonas aeruginosa. Infection starts in the external auditory canal and spreads to adjacent soft tissue, cartilage, and bone. Patients typically present with severe ear pain and otorrhoea (discharge from the ear). Can be fatal.
Rhinocerebral Mucormycosis
In patients with poorly controlled diabetes, especially those with diabetic ketoacidosis. Mould fungi colonising the nose and paranasal sinuses, spreading to adjacent tissues by invading blood vessels and causing soft tissues necrosis and bony erosion. Can invade into the brain.
Why are diabetic patients more at risk of UTIs?
UTI – Neurogenic bladder due to diabetic neuropathy leads to defects in bladder emptying so always a bit of urine left over, also sugary environment.
What common renal infections do people with diabetes get?
Increases risk of asymptomatic bacteriuria and pyuria (pus in the urine), cystitis (inflammation of the bladder) and upper UTI. Enterobacteriaceae such as E.Coli, Ps aeruginosa are common causes and often leads to blood stream infections.
