Mycobacterium tuberculosis L-forms(MTB-L), which has a deficient cell wall, shows various forms, various colors by acid-fast stain, osmosis pressure sensitivity and can not grow in normal isotonic culture medium, for all of the characters, misdiagnosis, underdiagnosis, difficulties of cure and recurrence became the crucial problems in the prevention and control of pulmonary tuberculosis. The recent research works on structure, biology, clinic, epidemiology and determination of MTB-L were reviewed in the present paper.

Objectives To explore the associations between drug efflux pump gene expression and phenotypic drug resistance as well as gene mutation patterns related to drug resistance of Mycobacterium tuberculosis.Methods Forty-five Mycobacterium tuberculosis isolates resistant to one or more of drugs including isoniazid, rifampicin, streptomycin and ethambutol, and 26 isolates all sensitive to the above four drugs from Tianjin Tuberculosis Control Institute in 2007 were involved in this study. Direct sequencing was applied to detect the mutations in the corresponding resistance genes(isoniazid:katG, inhA, oxyR-ahpC, ndh, rifampicin:rpoB, streptomycin:rpsL, rrs, and ethambutol:embB, embC and embA). After RNA extration and reverse transcription, real-time PCR was conducted to assess the expressions of putative drug efflux pump genes Rv1410c, Rv2136c, Rv0783c and Rv2136c, and Students' t test and ANOVA analysis were used to analyze the expression differences in Mycobacterium tuberculosis with different phenotypic drug resistance and drug resistance related gene mutation patterns.Results Compared to pan-sensitive isolates[(5.67±3.29)×10-5], Rv1410c showed higher expression in streptomycin[(8.48±6.33)×10-5, t'=2.18, P<0.05], isoniazid[(8.43±6.38)×10-5, t'=2.20, P<0.05], rifampicin[(9.59±7.27)×10-5, t'=2.29, P<0.05], multi-drug[(10.37±7.86)×10-5, t'=2.34, P<0.05] resistant isolates, and in isoniazid + streptomycin resistant isolates[(9.39±6.81)×10-5, t'=2.43, P<0.05];Rv2136c showed higher expression in isoniazid resistant[(3.51±2.43)×10-5, t'=2.03, P<0.05], multidrug-resistant isolates[(4.21±2.94)×10-5, t'=2.22, P<0.05] and resistant to isoniazid+streptomycin[(3.81±2.46)×10-5, t'=2.28, P<0.05] isolates . The expression of Rv0783c in rifampicin resistant isolates with rpoB 531 mutations [(5.41±3.03)×10-6] was higher than those with wild type of rpoB 531[(2.29±1.62)×10-6, t=2.81, P<0.05].Conclusions The expression of Rv1410c and Rv2136c are associated with mutiple-drug resistance of Mycobacterium tuberculosis.The expression of Rv0783c in rifampicin resistant isolates is associated with mutation in rpoB 531.