• Bacterial infection
• cystic fibrosis
• infection control

Lung disease in cystic fibrosis (CF) starts early in life. Infection, inflammation, reduced lung function and abnormal chest CT findings are present in a significant proportion of infants with CF at a time when many of these children have no clinically apparent lung disease.1–6 Infection and inflammation are intimately linked early in the course of CF lung disease.2 7–9 The detection of airway inflammation in the absence of apparent infection led to the speculation that CF is associated with an intrinsic abnormality of immune regulation.10 However, more recent data argue against a primary CF-associated dysregulation of local immune function where inflammation might precede infection; they rather support the central role of bacterial pathogens in initiating and sustaining the neutrophil-mediated airway inflammation characteristic of CF lung disease, with a higher inflammatory burden in children infected with Pseudomonas aeruginosa (PA) than in those infected with organisms other than PA or uninfected.6 11 12 Chronic respiratory infection is one of the main characteristics of CF and significantly contributes to morbidity and mortality.12 13 In young children Staphylococcus aureus, Haemophilus influenzae and PA are the major lower airway pathogens.12 13 Chronic infection with PA is known to be associated with a worse prognosis in children, adolescents and adults, and patients with mucoid PA strains do worse than those with non-mucoid strains.14–18 Thus, prevention or early detection and treatment of infection, in particular with PA, may prevent or delay irreversible lung damage from inflammation and consequently may improve prognosis. In order to prevent acquisition of PA, hygienic measures to decontaminate environmental reservoirs of this organism including medical equipment have been stressed, and CF centres have adopted meticulous microbiological surveillance and effective segregation policies to limit cross-infection between patients. Furthermore, several trials have been undertaken to assess the …