Cystic Fibrosis Flashcards
What is the pattern of inheritance of CF and what is the prevalence?
Autosomal recessive
1:25
Where is the CFTR gene found?
Long arm of chromosome 7
What is the most common mutation?
phe508del
DeltaF508
Function of CFTR?
Active transport for chloride
Regulates liquid volume on epithelial surface
Why does the mutation render patient more susceptible to bacterial colonisation and infections?
Abnormality leads to:
Reduced mucocilliary clearance, endocytosis of bacteria
Increased bacterial adherence
Why is CF a multisystem issue?
Chlorine is used all over body
How are neonatal’s diagnosed?
Screening
Rare - Meconium Illeus - content of babies bowel is very sticky
What is some common symptoms??
Recurrent chest infections Cough - sputum and haemoptysis Wheeze Failure to thrive Onset diabetes Weight loss Nasal polyps and sinusitis Male infertility
Some signs of CF?
Cyanosis
Clubbing
Crackles
How are neonates screened for CF?
Guthrie test for day 5 babies, a heel-pin test
Looks for immunoreactive trypsinogen and if positive:
Do a mutation analysis test and sweat chlorine test
What does a sweat test look for?
High chlorine
Other investigations that can be done?
Pulmonary function tests
CxR - over inflated lungs
What is the 2 cardinal features of CF?
Pancreatic insufficiency
Recurrent infections
Impact of pancreatic insufficiency?
Don’t produce lipases causing abnormal stools - pale/orange, greasy and offensive
Failure to thrive off breast milk
May have deficiencies of fat soluble vitamins (A, D, E, K)
Treatment for pancreatic insufficiency?
- Enteric coated enzyme pellets
- High energy high fat diet
- ADEK vitamin and mineral supplements
- H2 antagonist or proton pump inhibitors*
Results of recurrent infections?
- Bronchiectasis
- Pneumonitis
- Scarring
- Abscesses
What is done to try to stop frequency of recurrent infections?
- Segregation to prevent cross-infection
- Airway clearance
- Mucolytics
- Prophylactic antibiotics (against Staph aureus)
- Annual flu vaccination
What are the common pathogens causing re-current infections?
Staph aureus
H.Influenza in early years
Pseudomonas aeruginosa later years
What are some less common pathogens causing re-current infections?
Burkholderia cepacia
Stenotrophomonas maltophilia
Why does pseudomonas aeruginosa infect CF patients easier?
CFTR usually plays a role in endocytosis and destruction of this bacteria
What increases the colonisation rate of pseudomonas aeruginosa ?
Age possibly due to increased antibiotic use
What protects pseudomonas aeruginosa once colonised?
The bacteria undergoes a mucoid change and forms a biofilm in which microcolonies emerge.
Biofilm protects it and colonies from host defenced
Where is pseudomonas aeruginosa acquired from?
Environment
Other CF patients
Treatment of a pseudomonas aeruginosa infection?
1st step oral ciprofloxacin and nebulised colomycin
2nd step if 1st fails is IV cleftazidime and nebulised colomycin
