Invasion of murine respiratory epithelial cells in vivo by Burkholderia cepacia

Pulmonary infections caused by Burkholderia cepacia are an important cause of morbidity and mortality in cystic fibrosis (CF) patients. Several featur es suggestive of invasion and intracellular sequestration of B. cepacia in CF are persistence of infection in the face of antibiotic therapy and a pro pensity to cause bacteraemic infections in patients with CF. A mouse respir atory challenge model was used to investigate the invasion phenotype of B. cepacia in vivo. After intratracheal inoculation, epidemic B. cepacia strai ns translocated from lung to liver and spleen; however, all bacteria were c leared from all organs within 7 days. B. cepacia strains, irrespective of c able piliation, were capable of attaching to and then invading murine respi ratory tract epithelial cells, Histopathological examination of lungs showe d interstitial infiltrates comprised mainly of polymorphonuclear leucocytes and were associated with widened alveolar septa. Electron microscopy demon strated B. cepacia within epithelial cells and pulmonary macrophages. This study provides support for in-vitro observations that g, cepacia strains fr om patients with CF adhere to and then invade respiratory epithelial cells, The invasion phenotype in B. cepacia may be an important virulence factor in CF infections.