Survival and multiplication of Burkholderia cepacia within respiratory epithelial cells

Abstract

Objective: To investigate the ability of both clinical and environmental strains of Burkholderia cepacia, along with control strains of Pseudomonas aeruginosa and Escherichia coli, to invade a respiratory epithelial cell line, A549. Methods and Results: Using a double immunofluorescence labeling technique, a clinical strain of B. cepacia, C1359, and the clonally related strains A509 and J2315, were shown to invade A549 cells at a high level (2-8% A549 cells invaded) compared to environmental strains of B. cepacia NCTC 10661 and NCTC 10743 (0.5-1% of A549 cells invaded). Control strains of P. aeruginosa PAO1 and E. coli C600 did not appear to be able to invade respiratory epithelial cells using this method. Ceftazidime protection assays revealed that B. cepacia C1359 and NCTC 10743 were able to survive and multiply within A549 cells for > 24 h. In contrast, B. cepacia NCTC 10661, P. aeruginosa PAO1 and E. coli C600 failed to multiply within A549 cells, showing a significant decrease in numbers after 24 h. Conclusions: The ability to survive and multiply within respiratory epithelial cells may be an important virulence factor of B. cepacia infection in cystic fibrosis.