To determine the effect of bacterial coinfection in the CF context, CFBE41o- (homozygous for the ΔF508 CFTR mutation) and 16HBE14o- (usually differentiated bronchial epithelial cells) bronchial epithelial cells were infected with P. aeruginosa, M. abscessus, B. thuringiensis or a combination of bacteria. This evidence concerns the gene CFTR and cystic fibrosis.