Study on clinical separation characteristics of L-form of mycobacterium tuberculosis / 中国医师杂志

ABSTRACT

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-Lafter 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 rateafter 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 resistanceMTB-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.