Macrolide and azithromycin use are linked to increased macrolide resistance in Streptococcus pneumoniae

The connection between regional rates of antimicrobial resistance in Streptococcus pneumoniae and regional antimicrobial use in Finland was investigated. During the 6-year study period of 1997 to 2002, a total of 31,609 S. pneumoniae isolates were tested for penicillin resistance and a total of 23,769 isolates were tested for macrolide resistance in 18 central hospital districts in Finland. The regional macrolide resistance rates were compared with the local use of (i) all macrolides pooled and (ii) azithromycin. The penicillin resistance levels were compared with the consumption data for (i) penicillins, (ii) cephalosporins, (iii) all beta-lactams pooled, and (iv) all macrolides pooled. A statistically significant association between macrolide resistance and total use of macrolides and the use of azithromycin was found. Moreover, total use of beta-lactams and total use of cephalosporins were significantly connected to low-level penicillin resistance. A statistically significant association between penicillin-nonsusceptible isolates and penicillin or total macrolide consumption was not found. In conclusion, total macrolide use and azithromycin use are associated with increased macrolide resistance, and beta-lactam use and cephalosporin use are connected to increased low-level penicillin resistance in S. pneumoniae. Unnecessary prescribing of macrolides and cephalosporins should be avoided.