富西亚分枝杆菌从血液与静脉插管中的分离与鉴定

Identification and characterization of mycobacterium phocaicum from blood and vein

目的对从同一患者血液和静脉插管中分离的两株抗酸阳性细菌B0793、V1948进行菌种鉴定。方法广谱PCR扩增细菌的16S核糖体核糖核酸(16SrRNA)基因与核糖核酸(RNA)聚合酶β亚单位(rpoB)基因,测序其核苷酸序列并与相关菌种进行同源性比对及系统发育分析,以传统的表型实验对基因鉴定的结果进行验证,并参考CLSI M24-A的方法和解释标准进行分离株抗菌药物的药物敏感性试验。结果该2株细菌均为血平板上生长缓慢的革兰染色着色较淡的抗酸阳性杆菌,但2株细菌的菌落形态差别较大,B793在血平板培养4d形成直径1cm、米黄色、圆形、突起、不溶血、易乳化的光滑型菌落,V948则为直径约2cm、米黄色、豆腐渣样、边缘不规则的粗糙型菌落。16SrRNA基因和rpoB基因序列与富西亚分枝杆菌(mycobacterium phocaicum)的同源性均在99%以上,其半定量触酶、68℃触酶试验、5%NaCl耐受试验与脲酶试验阴性,亦符合富亚分枝杆菌的特征。结论该2株抗酸阳性细菌在分类学上属于富西亚分枝杆菌,其光滑型/粗糙型菌落变异为国际上首次发现。

Objective To identify the two acid-fast strains（B0793 and V1948） which were isolated from blood and vein of the same patient. Methods 16S rRNA and rpoB gene of two isolates were amplified by PCR and se- quenced. The rpoB gene sequences of the above isolates were analyzed and phylogenetic tree was constructed. Verifi- cation of isolates was carried out with the traditional phenotype results,interpretation of antibiotic susceptibility with CLSI M24 A reference method. Results The organisms were acid-fast and Gram-positive bacilli. Colonies grow slow- ly on 5 % sheep blood agar. But morphology difference between two strains was bigger,130793 form 1 cm size, rice, round, bumps, no hemolysis, smooth, easy emulsion type colonies, V1948 was about 2 cm in diameter size, rice, shoddy kind,edge irregular rough type colonies. The comparative study of 16S rRNA gone and rpoB showed the strain with above 99 % homology ＋o mycobacterium phocaieum, half quantitative catalase negative, 68 ~C catalaset negative, 5 % NaCI tolerance test negative and urease test negative, also accorded with the characteristics of mycobaeteria phocai- cum. Conclusion The two strains of bacteria are identified as mycobaeterium phocaicum that＇s smooth /rough type var：.ation is found for the first time.