Narrowing mutant selection window of Streptococcus suis by combination use of tylosin tartrate and amoxicillin sodium in vitro.

To develop strategies for reduce drug resistance development and provide rational application guidelines for available antibacterial medicines in clinic practice,the effect of combination use of tylosin tartrate and Amoxicillin Sodium on mutant selection window (MSW) of single drug group in vitro was investigated.Mutant prevention concentration (MPC) and MSWs were determined by spreading 1010 CFU/mL coccus on agar plates at different drug concentration for tylosin tartrate,Amoxicillin Sodium and tylosin tartrate combined with Amoxicillin Sodium.MSWs of tylosin tartrate,Amoxicillin Sodium and tylosin tartrate combined with Amoxicillin Sodium for Streptococcus suis strain D10 were 9.71,5.16 and 2.18 respectively.Tylosin tartrate combined with Amoxicillin Sodium decreased the MSW of tylosin tartrate by 3.5 times and Amoxicillin Sodium by 1.8 times to S.suis.Combinations of tylosin tartrate and Amoxicillin Sodium could decrease MSW to S.suis compared with individual drug administration.