The Study On Infection Caused By Mycobacterium Tuberculosis L-forms And Its Drug-resistance In Cases Of Pneumoconiosis Complicated With Tuberculosis In Huainan Mining District

Objective To study infection caused by Mycobacterium tuberculosis L-forms and its' drug resistance in cases of pneumoconiosis complicated with pulmonary tuberculosis and evaluate its clinical significance.Methods Sputum culture for Mycobacterium tuberculosis and its L-forms was conducted in both research and contrast groups, and IK acid fast smear was used for primary identification, the positive culture sedimentation was subsequently inoculated into identification culture medium to make further identification, PCR assay was also used to detect positive culture sedimentation of L-forms. Finally, reversion trial and drug resistance experiment were carried out to L-forms. Results In research group, of total 60 cases, culture positive rate of Mycobacterium tuberculosis was 23.4% (14 cases), and that of L-forms was 48.3% (29 cases), the difference was quite notable ( x2=7.95, P<0.005). Furthermore, the detected positive rate of L-forms ascended following the increase of pneumoconiosis stage (stage I was 30.0%, stage II was 62.5%, stage HI was 83.3%), the striking difference among various stages was seen( x2-8.88, P<0.05). Of 29 cases of positive culture sedimentation of L-forms, 23 cases were identified positive and 6 cases negative by PCR assay. While in contrast group, none of all 60 cases was found sputum Mycobacterium tuberculosis culture positive, but culture positive rate of its L-forms reach 5.0% (3 cases), which were all identified positive by PCR assay. No typical symptom of tuberculosis was found in patients infected by L-forms. All 32 L-forms were identified to be drug resisitant strains, the drug resistance rates to INH, RFP, EMB, SM were 75.0%, 90.6%, 78.1%, 50.0% respectively, multi-drug resistant strains were 27(84.4%), including 11 strains(34.4%) resisting to 4 kinds of drugs, 13(40.6%) to 3 kinds of drugs, 3(9.4%) to 2 kinds of drugs and 5(15.6%) to single drug.Conclusions The infectious rate of Mycobacterium tuberculosis L-forms in cases of pneumoconiosis complicated with tuberculosis is much high, and the status of drug resistance is pretty bad , most of L-forms own latent ability of reversion to bacterium form which can cause endogenic recurrence of tuberculosis. It is of important significance to carry out detecting Mycobacterium tuberculosis L-forms and its drug resistance, which can diminish mistakes in diagnosis on recurrence of tuberculosis, and facilitate early diagnosis of tuberculosis as well as usage of drugs.