Does Antimicrobial Usage Influence Antimicrobial Resistance?
Several investigators have reported the direct relationship between fluoroquinolone consumption and the emergence of quinolone-resistant strains. Chen et al. (1999) found that fluoroquinolone prescriptions increased from 0.8 to 5.5 per 100 persons per year between 1988 and 1997. The prevalence of pneumococci with reduced susceptibility to fluoroquinolones increased from 0 percent in 1993 to 1.7 in 1997-1998 (P = 0.01). The prevalence of resistant strains was higher in isolates from older patients (2.7 percent in those ³ 65 years vs. 1.0 in those 15 to 64 years, P < 0.001) and in those from Ontario vs those from the rest of Canada (1.5 vs. 0.4 percent, P = 0.001) where quinolone consumption was highest. Aguiar et al. (1992) related the increased consumption of quinolones to the presence of quinolone-resistant strains of E. coli isolated from community-acquired urinary tract infections over a four-year period (1988-1991). During this period the consumption of quinolones more than doubled