the small decrease was continuous or extrapolated from two measurements. Importantly, the decrease was from a very high level of resistance, and the change could not possibly affect the empirical utility of these drugs. Gottesman and co-workers presented data on ciprofloxacin resistance in E. coli in relation to a nationwide restriction in ciprofloxacin use in Israel (due to a threat of anthrax attacks). Interrupted time series analysis showed a significant decrease in cipro- floxacin resistance from 12% to 9% in the course of a 6-month intervention, gradually reaching a reduction from 7,000 DDD/month to 4,500 DDD/month (66). The study has several limitations. There was little information on methodological or interpretative aspects of susceptibility testing. Thus, associated resis- tance rates in fluoroquinolone-resistant E. coli were not reported or discussed. The rapid effect on resis- tance rates is theoretically unlikely as recent data indicate the initial fitness cost of fluoroquinolone resistance in E. coli to be rapidly compensated for (14).
In view of the results of the seven studies performed so far on the effects of reduced antibiotic use in the community (Table I), together with the pronounced associated resistance rates and seemingly low epide- miological fitness cost of resistance determinants, we should probably not expect that even major antibiotic interventions will dramatically affect resistance rates in the community (41). However, new strategies might prove efficient to counteract resistance devel- opment in some species. Vaccination against impor- tant serotypes of S. pneumoniae has been proven effective in reducing antibiotic resistance in clinical infections (58,67).