Cystic fibrosis Flashcards
What is CF?
Autosomal recessive condition (1:2500). Most common life-shortening disorder in N.European populations. Mutation of CFTR gene - mutation present determines severity of disease. This channel is needed for Cl transport. Reduced Cl efflux and increase Na influx causes collapse of cilia and excessive inflammation.
What are the common clinical features in CF patients?
Recurrent chest infections, failure to thrive, nasal polyps/sinusitus, male infertility. Reduced mucociliary clearance, increased bacterial adherence and reduced endocytosis of bacteria.
Describe neonatal screening for CF.
Guthrie test on day 5. Screen for immunoreactive trypsinogen. If positive, mutaton analysis performed. Positive, sweat test - test how much Cl is in sweat. This will be higher in CF (>60). Screening introduced in Scotland in 2003.
What are the 2 cardinal features of CF?
Pancreatic insufficiency: abnormal stools, failure to thrive. Treated by enteric coated enzyme pellets, > energy diet, fat-soluble vitamin/mineral supplements and H2 antagonist/PPI’s.
Recurrent bronchopulmonary infection: pneumonitis, bronchiectasis (aggressive and progressive), scarring and abscesses.
What are common respiratory pathogens in CF?
S.aureus, H.influenzae (early years) and Pseudomonas aeruginosa (later). Need to reduce bacterial load and inflammation.
What are less common respiratory pathogens in CF?
Burkholderia cepacia, Stenotrophomonas maltophilia, Alcaligenes xylosoxidans and Atypical mycobacteria.
What are other manifestations of CF?
GI: dysmotility, meconium ileus, gastro-oesophygeal reflux, distal intestinal obstruction and constipation/rectal prolapse. Also hepatopathy - venous congestion of liver. Upper airway polyps, diabetes, bone (osteopenia), heat exhaustion, bilateral absence of vas deferens and vaginal candidiasis.
What is survival related to in CF?
FEV1 as CF causes progressive airflow obstruction. Nocturnal NIV (non-invasive ventilation can be given. Pneumothorax is associated with poor prognosis.
Why is Pseudomonas aeruginosa so dangerous for CF patients?
Once colonised, undergoes a mucoid change and forms a biofilm - MDR. This can cause a rapid decline in lung function. Give oral ciprofloxacin and nebulised colomycin. Fails, ceftazidime and nebulised colomycin.
Describe infection with Burkholderia cepacia.
Resistant to most antibiotics and associated with rapid decline in lung function.
Describe infection with Stenotrophomonas maltophilia and Mycobacterium abscessus.
S.maltophilia: gram negative with multible antibiotic resistance. M.abscessus: resistant to all anti-suberculous chemotherapy, a contraindication for transplantation.
How are recurrent respiratory tract infections treated?
Oral Ab: Staph, Haemophilus and Pneumococcus. IV Ab: Pseudomonas, Burkholderia and Stentrophomonas. Give 2 antibiotics: a B-lactam and aminoglycoside.
What is Ivacaftor?
New drug for CF that binds to CFTR and improves transport of Cl ions. Can only be given to patients with G551D mutation. > lung function (10% predicted), weight gain,
When in lung transplant indicated?
Rapidly deteriorating lung function, FEV1
Does CF affect fertility?
Only in males: > 95% infertile due to blocked/absence of vas deferens. Can give ICSI (intra-cytoplasmic sperm injection) - 30% success rate.
