However, a comparative study that screened a large panel of ePA isolates (including PES) against unique strains from CF patients for virulence traits including virulence factor production, biofilm formation, planktonic growth, mucoidy, and antibiotic susceptibility, showed that PES isolates do not behave significantly differently than unique/non-clonal isolates, albeit these were conducted in vitro and may not be reflective of the complexity of the lung environment (Duong et al., 2015). This evidence concerns the gene TIMP1 and cystic fibrosis.