In conclusion, our results suggest that careful control of culture and propagation of QS deficient PAO1 derivatives to prevent additional mutations and the loss of such important characteristics as twitching motility may eliminate a significant proportion of the previously observed differences in infectivity and persistence of QS-deficient bacteria and wild-type P. aeruginosa in animal models, and allow a more precise evaluation of the importance of QS and QS-regulated gene expression in bacterial virulence and pathogenesis of infection. This evidence concerns the gene SMOX and infection.