摘要：
目的 探讨结核分枝杆菌L型(MTB-L)实验室培养及鉴定,在涂阳肺结核患者中分离率及耐药性,提高临床对MTB-L的重视.方法 随机选择长沙市中心医院治疗的涂阳肺结核患者222例,进行MGIT 960和改良92-3TB-L液体培养.MGIT 960报阳后,取改良92-3TB-L液体培养基沉淀涂片抗酸染色,进行初步筛查.将疑似L型阳性菌株培养物转种改良TSA-L型固体培养基,观察菌落特征和镜下特征.用抗酸染色、结核DNA扩增实验确认菌株性质.对MTB-L进行常规药敏试验以及耐药基因突变位点分析.结果 MTB-L鉴定:培阳菌株经固体培养,可见“油煎蛋”、“颗粒”、“丝状”样菌落,结核DNA确认为MTB.临床分离率:经过培养,单独细菌型阳性率为50.90％(113/222),细菌型和L型两者同时存在为15.32％(34/222),单独MTB-L型阳性率为2.25％(5/222).耐药性:MTB-L型对链霉素、异烟肼、利福平、乙胺丁醇耐药,耐药基因位点未发生突变.结论 临床实验室应常规开展结核分枝杆菌L型细菌的培养,提高临床对MTB-L型细菌的重视.%Objective To explore the laboratory culture and identification of Mycobacterium tuberculosis L forms (MTB-L),isolation rate and drug resistance in smear-positive tuberculosis patients,and to improve clinical attention to MTB-L.Methods 222 smear-positive pulmonary tuberculosis patients treated in our hospital from September 2017 to December 2017 were randomly selected for MGIT 960 and 92-3TB-L liquid culture.After MGIT 960 was reported positive,acid-fast staining was performed on the precipitated smears of 92-3TB-L liquid medium for preliminary screening.The suspected L-positive strain culture was transformed into improved TSA-L solid medium to observe the colony characteristics and microscopic characteristics.The properties of the strain were confirmed by acid-fast staining and tuberculosis DNA amplification.Drug susceptibility and mutation sites of drug resistance genes were analyzed in MTB-L.Results Ⅰ-dentification of MTB-L:after the positive strain has been cultured,the colonies have the characteristics of "fried egg sample","particle-like" and " filament-like".MTB confirmed by tubercle DNA amplification experiments.Isolation rate:after cultured by MGIT 960 and Modified 92-3TB-L medium,the positive rate of single bacterial type was 50.90％,(113/222) the positive rate of both bacterial type and L type was 15.32％ (34/222),and the positive rate of MTB-L type was 2.25％ (5/222).Drug resistance:MTB-L was resistant to Streptomycin,Isoniazid,Rifampin,and Ethanol butylamine.No mutation was found in the drug resistance gene loci.Conclusions Clinical laboratory should routinely develop the culture of L-form of Mycobacterium tuberculosis bacteria,and increase the clinical attention to MTB-L.
