Phenotype and genotype heterogeneous resistance of L-forms of Mycobacterium tuberculosis by magnetic nanoparticle

We studied factors influencing the phenotype and genotype heterogeneous resistance of L-forms of Mycobacterium tuberculosis (MTB-L). Three hundred patients with tuberculosis admitted to the Sixth People's Hospital of Nantong from 2014 to 2016 were selected. MTB-L was cultured and rifampicin (RFP) susceptibility was tested using sputum samples. The magnetic nanoparticle was used to extract the DNA of samples. DNA sequencing was used to detect the mutation of the rpoB gene core region for isolated MTB-L strains and heterogeneous resistance was analyzed. A total of 126 MTB-L strains were isolated from the sputum samples of 300 tuberculosis patients. No mutation in the core region of the rpoB gene was detected in 56 RFP-sensitive MTB-L strains. Among 70 phenotypically resistant strains, 32 had mutations in the core region of the rpoB gene, with amino acid changes at sites 511, 516, 526, and 531. No rpoB gene mutation was found in the other 38 phenotypic drug-resistant strains. The MTB-L phenotype and genotype displayed a certain degree of heterogeneous resistance. Changes in cell membrane structure is one important reason. The duration of disease, medication history, and structural changes of the lung are important factors.