猪源链球菌对大环内酯类主要耐药基因的检测

Detection of the major macrolide resistance genes in pig Streptococcus isolates

为了解猪源链球菌对红霉素相关耐药基因ermB、ermA和mefA的分布,对河北省及辽宁部分地区的64株猪源链球菌分离株,用PCR方法检测51株红霉素耐药株和13株红霉素敏感株中ermB、ermA和mefA基因。结果显示,耐药菌株中ermB基因的检出率为98.04%(50/51),ermA的检出率为25.49%(13/51),没有检出mefA基因。初步表明河北省及辽宁部分地区的猪源链球菌对红霉素的耐药机制以ermB基因介导为主。20株菌的ermB基因核苷酸序列与GenBank中同源序列相似性为99%～100%。与参照序列AJ972604.1相比,20株菌的ermB氨基酸序列的突变位点较少,主要有Thr 75→Ser、Ser 100→Asn、Arg 118→His、Leu 175→Ile,以100和118位突变为主,进一步说明ermB基因是相对稳定的。

To investigate the distribution of ermB,ermA and mefA that related to the erythromycin resistance gene,64 pig Streptococcus isolates from different areas in Hebei and Liaoning provinces were detected by PCR amplification.The results showed that,among the 51 drug-resistant strains,98.04%（50/51） harbored ermB gene,25.49%（13/51） isolates contained ermA gene,and none of these strains was positive for mefA gene.It is considered that erythromycin resistance mechanism of pig Streptococcus isolates is mainly mediated by ermB gene.Nucleotide sequences comparison showed that the 20 strains ermB genes nucleotide sequences had a 99%-100% similarity to the GenBank.Compared with the reference sequence of AJ972604.1,Ser to Asn mutation at position 100 and Arg to His mutation at position 118 of ermB were mainly detected in the 20 strains,indicating that the ermB gene is relatively stable furtherly.