Cystic fibrosis (CF) screen




  • Sputum is the recommended specimen for routine sampling
  • A cough swab should only be used if a patient cannot expectorate as the sensitivity for isolation of key pathogens such as Pseudomonas aeruginosa and Staphylococcus aureus is considerably less than sputum
  • Samples are cultured for both routine respiratory and cystic fibrosis (CF) associated pathogens
  • Sputum samples may be examined for Mycobacteria on request. Frequency should not be more than once every two months.

Sample requirements



60 mL wide-mouthed container

  • Sputum rather than saliva is required
  • Expectorate sample directly into the container
  • Physiotherapy may be required



Cough swab

Standard charcoal transport swab

  • Hold the swab as far back in the throat as possible while the patient coughs
  • Place swab into transport medium

60 mL wide-mouthed container

Charcoal transport swab

Required information

  • Current or recent antibiotic therapy
  • Antibiotic allergies



Transport without delay to ensure survival of fastidious organisms. Where transport is difficult, specimens may be cultured up to 48hr after collection. If specimens are not processed on the same day as they are collected, interpretation of results should be made with care.

If transport is delayed, refrigeration is preferable to storage at ambient temperature.

Cough swabs:

Transport without delay, if transport is delayed store at ambient temperature

Turnaround time

Up to 8 days

Page last reviewed: 12/12/2017