Local Changes in Rates of Group A Streptococcus Disease and Antibiotic Resistance are Associated with Geographically Widespread Strain Turnover Events.

摘要

Group A Streptococcus pyogenes is a primary agent of respiratory disease in military environments. Antibiotic prophylaxis is used to prevent spread of this pathogen among recruits. We describe effects of dynamic strain turnover and antibiotic prophylaxis on rates of antibiotic resistance and disease through analysis of the temporal and geographic strain distributions, disease rates, and patterns of antibiotic resistance of 802 Streptococcus isolates from 10 US military facilities collected from 2002 through 2007. Most of these sites provided penicillin prophylaxis for all nonallergic recruits, and some sites also used macrolide prophylaxis for penicillin-allergic subpopulations. Macrolide resistance peaked at 25% during 2004, correlating with the geographically widespread dominance of a single strain (M75). The resistant strain was not retained regardless of macrolide prophylaxis, and resistance rates decreased upon replacement of M75. Disease rate was similarly correlated with strain dominance patterns. Temporal correlation in the proportional strain distributions at multiple locations suggest the accompanying shifts in antibiotic resistance profiles may be driven by strain replacements occurring on larger scales. The data suggest that rapid strain-typing methods using sentinel-site samples from a subset of affected locations could offer significant predictive value in terms of both antibiotic susceptibility and potential morbidity patterns.