21株快速生长分枝杆菌的鉴定与特征

目的 对临床分离的21株快速生长分枝杆菌进行种型鉴定和特征分析。方法 对广东省中医院2010～2015年收集的21株快速生长分枝杆菌进行传统的表型形态学鉴定,16S rRNA基因和ropB基因测序鉴定和微量肉汤稀释法的药敏试验,结合光滑/粗糙型变异分析其菌型特征和耐药性。结果 21株分离株均为血平板上7天内生长良好的抗酸阳性菌,经16S rRNA基因和ropB基因测序鉴定均为分枝杆菌。根据生长的菌落特性,12株为光滑型,7株为粗糙型,2株为中间型。涂制湿片显示,12株光滑型分枝杆菌和2株中间型分枝杆菌均能在生理盐水表面形成一层漂浮的油脂(可能为分枝菌酸)。药敏试验显示,快速生长分枝杆菌对阿米卡星、头孢西丁、克拉霉素的敏感性较好。统计学分析显示,粗糙型具有比光滑型菌株更高的耐药性。结论 快速生长分枝杆菌可分为光滑型、粗糙型和中间型3种菌落表型,其中油脂飘浮现象能用于中间型和光滑型分枝杆菌的快速鉴定。

Characterization of Twenty-one Strains of Rapidly Growing Mycobacteria

Objective To analyze their characteristics of21 clinical isolates of rapidly growing Mycobacteria.Methods The 21 rapidly growing Mycobacteria strains,collected from Oct.2010 to Oct.2015, were identified by the morphologic features(specially the S/Rcolony morphology)and sequences analysis based on 16S rRNA and ropB gene.Theantimicrobial susceptibility tests were performed by broth microdilution methodcombining to the S/R colony morphology.Results All of the 21 strains could form visible colonies within 7 days on blood agar,which were acid fast bacillus and lastly identified to the genus Mycobacteria by 16SrRNA gene and ropB gene sequences.To the morphologic features,12 strains weresmooth,7 strains were rough and 2 strains were intermediate type.The wet smearshowed all smooth and intermediate strains could form floating oily substances(possible mycolic acid)in the surface of normal saline liquid.The antimicrobial susceptibility testing showed that rapidly growing Mycobacteria were sensitive to amikacin,cefoxitin and clarithromycin.Moreover,the statistical analysis show that rough colony had higher drug-resistance than smooth colony.Conclusion Rapidly growing mycobacteria can be divided into smooth,rough and intermediate types accoding to the colony morphology.The wet smear with floating oil can used to the rapid identification of the smooth and intermediate colony type of Mycobacteria.