不明原因发热患者骨髓中分离解糖葡萄球菌的实验研究

目的 建立对解糖葡萄球菌的快速分子诊断,为临床药物治疗提供帮助.方法 采用碱裂解法从血培养瓶中提取DNA,用16S rRNA和gap基因分别对细菌进行检测,构建进化树进行同源分析,同时用连续梯度药敏试验(E-test)方法进行药敏试验.结果 16S rRNA序列分析显示,与该细菌＞99.0％相似率的细菌有5种,同源分析显示,该菌与解糖葡萄球菌低度同源为45.0％;gap基因分析显示与该细菌＞99.0％相似率有解糖葡萄球菌1种,具有高度同源为100.0％;E-test试验结果万古霉素1.5μg/ml、青霉素0.002 μg/ml、克林霉素0.023μg/ml、左氧氟沙星0.094 μg/ml和甲硝唑256 μg/ml.结论 gap基因序列分析能够及时准确鉴定解糖葡萄球菌,在数据同源分析方面要优于16S rRNA基因.

Experimental study of bone marrow-derived Staphylococcus saccharolyticus from patient with unknown fever

OBJECTIVE To establish the rapid molecular diagnosis of Staphylococcus saccharolyticus and provide assistance for clinical drug therapy.METHODS Alkaline lysis method was used to extract DNA from positive blood culture bottles.16SrRNA and gap gene sequences were obtained.These bacteria were identified with phylogenetic analysis,meanwhile,E-test method was used for antimicrobial susceptibility testing.RESULTS Analysis of 16SrRNA sequence revealed that there were 5 bacterial species with more than 99.0% of homology as Staphylococcus specie and phylogenetic analysis showed it had low degree homology with S.saccharolyticus(45.0%).In contrast,gap gene sequencing allowed undoubted identification of the isolate as S.saccharolyticus since the maximum of homology was observed with S.saccharolyticus(99.0%) and the confidence was 100.0%.Antimicrobial susceptibility testing by E-test method showed that the MICs of vancomycin,penicillin,clindamycin,levofloxacin and metronidazole were 1.5μg/mL,0.002μg/mL,0.023μg/mL,0.094μg/mL and 256μg/mL,respectively.CONCLUSION Analysis of gap sequence contributes to the timely and accurate identification of S.saccharolyticus,which is superior to 16SrRNA in the analysis of homology.