Which genus is a notable cause of lower respiratory tract infections in cystic fibrosis patients besides Pseudomonas aeruginosa?

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

Answer: (B)

In cystic fibrosis lung disease, the microbiology focus is on organisms that chronically colonize the airways. Besides Pseudomonas aeruginosa, an important genus seen in CF lower respiratory tract infections is Burkholderia cepacia. Members of the Burkholderia cepacia complex can spread between CF patients, are associated with rapid and severe decline in lung function (sometimes termed cepacia syndrome), and often show significant antibiotic resistance, making management challenging. This combination of transmissibility, virulence, and resistance makes Burkholderia cepacia a notable CF pathogen beyond Pseudomonas. The other organisms listed are less characteristic CF pathogens: Actinobacillus actinomycetemcomitans is primarily an oral bacterium; Chryseobacterium meningosepticum is more commonly linked to hospital-acquired infections; Serratia marcescens can cause various infections but is not as defining a CF lung pathogen as Burkholderia cepacia.