THE EFFECT OF CHANGES IN THE CONSUMPTION OF MACROLIDE ANTIBIOTICS ON ERYTHROMYCIN RESISTANCE IN GROUP-A STREPTOCOCCI IN FINLAND

Background In the early 1990s there was an increase in erythromycin re sistance among group A streptococci in Finland. In response, policies regarding outpatient antibiotic therapy were changed, and nationwide r ecommendations were issued that called for reductions in the use of ma crolide antibiotics for respiratory and skin infections in outpatients . We studied the effect of this policy on the pattern of erythromycin resistance throughout Finland. Methods From 1991 through 1996, a total of 39,247 group A streptococcal isolates from throat swabs (82 percen t of the isolates) and pus samples (18 percent) and 290 isolates from blood cultures were studied in regional microbiology laboratories. The susceptibility of the isolates to erythromycin was tested by the disk -diffusion or the screening-prate method. Results Consumption of macro lide antibiotics decreased from 2.40 defined daily doses per 1000 inha bitants per day in 1991 to 1.38 in 1992 (P=0.007) and remained near th e lower level during the study period. The change in consumption was f ollowed by a steady decrease in the frequency of erythromycin resistan ce among group A streptococcal isolates from throat swabs and pus samp les, from 16.5 percent in 1992 to 8.6 percent in 1996 (odds ratio for 1996 as compared with 1992, 0.5; 95 percent confidence interval, 0.4 t o 0.5). Conclusions in Finland, after nationwide reductions in the use of macrolide antibiotics for outpatient therapy, there was a signific ant decline in the frequency of erythromycin resistance among group A streptococci isolated from throat swabs and pus samples. (C) 1997, Mas sachusetts Medical Society.