Figure 2.

Quorum sensing phenotypes of 11 paired P. aeruginosa isolates. Each pair was obtained from a different patient. The time interval between the paired two isolates was 81 (35–98) days apart. In patients who had isolates shifting from non-MDR to MDR, quorum sensing phenotypes, including signal molecules 3OC12-HSL (A) and C4-HSL (B), and virulence factors pyocyanin (C) and protease (D), were significantly poorer in recurrent isolates than in initial ones; while in patients who had paired isolates maintaining non-MDR, no significant difference of QS phenotypes was found between initial and recurrent isolates. For initial isolates vs. recurrent isolates, ^* p < 0.05; ns, nonsignificant; MDR, multidrug resistance; OD, optical density; RFU, relative fluorescence unit.