“…Other emerging features associated with the adapting CF Pa are more perplexing and include: i) the evolution of slow-growing auxotrophic strains from initially rapidly-growing prototrophic strains; ii) the rise of mutations in virulence determinants from highly virulent wild-type strains; and iii) the emergence of antibiotic hyper-susceptible strains from antibiotic resistant parental strains (Figures 1 and 2) (Agarwal et al, 2005;Barth et al, 1998;Feary et al, 1969;Haussler et al, 1999;Hoboth et al, 2009;Hogardt et al, 2007;Qin et al, 2012;Starkey et al, 2009;Taylor et al, 1992;Thomas et al, 2000;Yang et al, 2008). Moreover, the prototrophic and auxotrophic isogenic strains together show high density growth both in vitro and in vivo, and display variable growth properties and antimicrobial susceptibilities, irrespective of their specific nutrient requirements (Palmer et al, 2007;Qin et al, 2012).…”