Besides Pseudomonas aeruginosa, which organism is an important cause of lower respiratory tract infections in patients with cystic fibrosis?

• A. Actinobacillus actinomycetemcomitans
• B. Burkholderia cepacia
• C. Chryseobacterium meningosepticum
• D. Serratia marcescens

Answer: (B)

In cystic fibrosis, the lungs are repeatedly colonized by bacteria, and while Pseudomonas aeruginosa is the most common offender, Burkholderia cepacia stands out as a major cause of lower respiratory tract infections with CF. This organism can establish chronic infection in CF airways and is associated with rapid clinical decline and high mortality, a pattern sometimes called cepacia syndrome. It is often resistant to many antibiotics, making eradication challenging and treatment difficult, which is why its presence influences management and prognosis, including infection-control measures to prevent spread between CF patients. The other organisms listed can cause infections but do not have the same strong, characteristic association with CF lung disease and outcomes as Burkholderia cepacia.