Study on the Streptococcus pneumoniae resistance induced by erythromycin in vitro / 第三军医大学学报

ABSTRACT

Objective To establish erythromycin resistance models of Streptococcus pneumoniae for analysis of the mutations in the binding domain of erythromycin. Methods Streptococcus pneumonia tigr4 and two clinical sensitive isolates were induced with erythromycin by minimum inhibitory concentration (MIC) method for antimicrobial susceptibility, and then the rplD, rplV genes, and 23S rRNA in sensitive and resistant strains were amplified by PCR and RT-PCR for sequencing. CPHmodels-2.0 was used to predict the spatial structures of ribosomal protein L4 and L22 coded by rplD and rplV genes. Results MIC of Streptococcus pneumonia tigr4 increased from 0.0312 mg/L to 256mg/L while MICs of the two clinical isolates increased from 0.0312 mg/L to 32 mg/L. Comparison of the pre-and post-induction results showed V32A mutation in ribosomal protein L4, D35G mutation in ribosomal protein L22, and 67QK68 to 67RE68 mutations in ribosomal protein L4. Changes in spatial structure was found in SiThe ribosomal protein L22 and ribosomal protein L4 due to D35G, Q67R, and K68E mutations respectively. Conclusion Streptococcus pneumonia can be induced to resistant to erythromycin in vitro. The mechanisms of resistance may be relate to the new mutations in the binding domain of erythromycin.