The morbidity and mortality of patients with cystic fibrosis (CF) is primarily determined by chronic and debilitating lung infections caused by a surprisingly narrow spectrum of bacterial pathogens. Pseudomonas aeruginosa is by far the most prevalent life-threatening CF pathogen. In the absence of aggressive early therapy, it infects the majority of adult patients and determines long-term survival. The epidemiology of CF pulmonary infections continues to evolve. Amongst the most recent CF pathogens to have emerged are a group of closely related bacteria, known as the Burkholderia cepacia complex. These organisms are a particular challenge due to inherent antibiotic resistance, the potential for patient-to-patient spread, and the risk of 'cepacia syndrome', a rapid fulminating pneumonia sometimes accompanied by bacteremia. Strict cross-infection control was prompted by early epidemiological experience of the B. cepacia complex and is essential in the management of all CF pathogens.