In CAP, standard courses of fluoroquinolones have been of 7-14-days duration. Nevertheless, clinical trials of shorter courses of therapy do appear safe and effective in many series. In AECB, a number of studies involving fluoroquinolones have demonstrated excellent cure and eradication rates with shorter than standard courses of treatment. Habib reported 92% success rates in patients receiving either 5-7 days of levofloxacin or 7-10 days of cefaclor (18). In more severely ill subjects, Masterton reported cure rates at 7-10-days post-treatment of 83% and 85% in per-protocol groups receiving levofloxacin 500 mg o.d. for 5 and 7 days, respectively (19). Furthermore, the bacteriological eradication rates were similar both overall (82% vs. 83%) and in respect to H. influenzae (88% vs. 79%) and clinical results in culture-proven cases were identical (84.5% vs. 85%). With respect to resistance development, studies of fluoroquinolones suggest that, in AECB at least, rapid eradication is the most important factor in reducing the potential for emergence of resistance. Interestingly, shorter courses of fluoroquinolones may also reduce the emergence of resistance (20).