question: In the B/H24 sublineage, the introduction of the fluoroquinolone resistance by mutations in gyrA and parC (B2/H24R) and the introduction of blaCTX-M-15 (B3/H24Rx) were also estimated to have occurred around 1987 concurrently with the widespread clinical introduction of extended-spectrum cephalosporins and fluoroquinolones (Fig. 3). 