Report of the UK Cystic Fibrosis Trust Antibiotic Working Group

3.1 Introduction3. IDENTIFICATION OF LOWER AIRWAY INFECTIONIdentification of lower respiratory infection in individuals with CF represents a challenge. Youngchildren may not expectorate sputum, even when they have a wet cough. Many patients with CF havelittle lung damage and so do not have sputum to expectorate. However, in order to avoid progressivelung damage and bronchiectasis, it is essential to identify and treat lower respiratory infection at anearly stage. It is a paradox in CF that as treatment of pulmonary infection improves, diagnosis of suchinfection becomes more difficult. There are a number of situations where diagnosis of pulmonaryinfection is important, for different reasons.• The asymptomatic patient without chronic airway infection. Identification of Pseudomonasaeruginosa from the respiratory culture of asymptomatic patients facilitates prompt treatment,which results in eradication in a significant number. 1;2 Not treating P.aeruginosa results inchronic airway infection. 1;3-6• The symptomatic patient without chronic airway infection. The identification of airwayinfection in the symptomatic patient facilitates appropriate treatment. 7• The patient with chronic airway infection. In these patients, regular culture of respiratorysamples facilitates:• Monitoring individuals for change in sensitivity patterns 8;9• Identification of new strains/pathogens in an individual 10–12• Identification of emergence of epidemic strains in a clinic population 8;13;143.2 Methods to identify airway infectionIn the patient who is not productive of sputum, the following microbiology specimens can becollected. The advantages and disadvantages of each are summarized in table 1.• Cough swab• Cough plate• Oropharyngeal culture (throat)• Laryngeal or naso-pharyngeal aspirate• Exhaled breath condensate• Induced sputum following hypertonic saline• Bronchoalveolar lavage• Serology (functional P.aeruginosa antibodies)In the patient who does produce sputum, a sputum sample is likely to be the best clinical specimen,for practical purposes.Cystic Fibrosis Trust 3.0March 2009