Abstract:Objective To evaluate the administration scheme of ceftriaxone, levofloxacin and moxifloxacin based on Streptococcus spp. collected by national blood infection Bacterial Resistant Investigation Collaborative System (BRICS), provide basis for clinicians to use antimicrobial agents rationally. Methods Antimicrobial susceptibility of ceftriaxone, levofloxacin and moxifloxacin was determined by agar dilution method, probability of target attainment (PTA)and cumulative fraction of response (CFR)of different administration schemes of three antimicrobial agents was studied with Monte Carlo simulation method. Results Minimum inhibitory concentration (MIC) detection result showed that the susceptibility rates of ceftriaxone, levofloxacin and moxifloxacin to Streptococcus pneumoniae were 82.22%, 97.78% and 97.78% respectively, to other Streptococcus were 97.66%, 80.14% and 81.07% respectively. Monte Carlo simulation result showed that CFR were both ≥ 90% when ceftriaxone was used to treat streptococcus spp. infection at doses of 1 g/24 hour and 2 g/24 hour; CFR was 93% when levofloxacin was used to treat other streptococcal infection at dose of 750 mg/24 hour; CFR was < 90% when levofloxacin was used to treat Streptococcal spp. infection at dose of 500 mg/24 hour; CFR was both >90% when moxifloxacin was used to treat other streptococcal infection at doses of 400 mg/24 hour and 800 mg/24 hour, CFR was both < 90% when moxifloxacin was used to treat Streptococcus pneumoniae. Conclusion When ceftriaxone, levofloxacin and moxifloxacin are used to treat bloodstream infection caused by Streptococcus, different dosage of ceftriaxone should be selected for effective treatment according to different MIC value, therapeutic effect of levofloxacin at 750 mg/24 hours is significantly better than that at 500 mg/24 hours, moxifloxacin is not recommended for the treatment of Streptococcus spp. infection if MIC value is not within the susceptible range.