The emergence of drug-resistant tuberculosis (TB) is a growing problem worldwide. The lack of safe and effective drugs, together with the frequent development of adverse drug reactions can result in worse outcomes. Therefore, new TB drugs able to bolster the current TB treatment regimen are urgently required. Novel drugs that are effective and safe against Mycobacterium tuberculosis are required to reduce the number of drugs and the duration of treatment in both drug-susceptible TB and multi-drug-resistant (MDR)-TB. This review covers promising novel TB drugs and regimens that are currently under development. Bedaquiline and delamanid are the most promising novel drugs for the treatment of MDR-TB, each having a high efficacy and tolerability. However, the best regimen for achieving better outcomes and reducing adverse drug reactions remains yet to be determined, with safety concerns regarding cardiac events due to QT prolongation still to be addressed. Pretomanid is a novel drug that potentially shortens the duration of treatment in both drug-susceptible and drug-resistant TB. Many regimens consisting of injection free drugs with shorter treatment duration compared to the conventional treatment are now undergoing clinical trials. Therefore a simple and short treatment with higher efficacy, and lesser adverse drug reactions and drug-drug interaction is expected for patients with MDR-TB.
Antitubercular Agents ; Drug-Related Side Effects and Adverse Reactions ; Humans ; Mycobacterium tuberculosis ; Tuberculosis ; Tuberculosis, Multidrug-Resistant

Clinical Laboratory Techniques ; Drug Resistance, Bacterial ; Humans ; Microbial Sensitivity Tests ; Mycobacterium tuberculosis ; drug effects ; Tuberculosis ; diagnosis

OBJECTIVETo explore the induction of L-forms of Mycobacterium abscess using isoniazid.

METHODSMycobacterium abscess were cultured in aqueous culture media in the presence or absence of 128 µg/ml isoniazid. The culture media containing isoniazid were filtered with 0.45 µm membrane, and the filtrate was subcultured in nutrient agar media for reversion. The isoniazid-free and isoniazid-containing media and the reversion bacteria were observed for cell wall integrity by cell wall staining and transmission electron microscopy, and the microstructures of the cell surfaces were observed by scanning electron microscopy. The isoniazid-containing culture was subcultured in L-form agar media, and the isoniazid-free culture and the reversed bacteria in nutrient agar media to observe the colony morphology. The reversed and non-induced bacteria were identified for 16S rDNA.

RESULTSThe bacteria induced with 128 µg/ml isoniazid showed cell wall defect, presenting with a spherical cell morphology and typical fried egg-like colonies in L-form agar media, while in isoniazid-free cultures, the cells showed intact cell walls with rod-like shapes and round colony morphologies on nutrient agar. The reversed bacteria, showing also intact cell walls with rod-like shapes and round colonies on nutrient agar, had identical 16S rDNA with the non-induced bacteria.

CONCLUSIONIsoniazid can induce the L-forms of mycobacterium abscess for use in studies of multidrug resistance and treatment of the bacteria.

Cell Wall ; drug effects ; Culture Media ; Isoniazid ; pharmacology ; L Forms ; drug effects ; Mycobacterium tuberculosis ; cytology ; drug effects

Pyrazinamide (PZA) is one of the most important drugs for the treatment of Mycobacterium tuberculosis infection. However, the increasing frequency of PZA-resistant strains limits its effectiveness. In Korea, most PZA-resistant strains also exhibit both isoniazid and rifampin resistance making it essential to identify these resistant strains accurately and rapidly for effective treatment of mycobacterial infection. In this study, the characteristics and frequency of mutations of the pncA gene encoding pyrazinamidase were investigated in PZA-resistant clinical isolates from Korea. Automated DNA sequencing was used to evaluate the usefulness of DNA-based detection of PZA resistance. Among 95 PZA-resistant clinical isolates, 92 (97%) exhibited mutations potentially affecting either the production or the activity of the enzyme. Mutations were found throughout the pncA gene including the upstream region. Single nucleotide replacement appeared to be the major mutational event (69/92), although multiple substitutions as well as insertion and deletion of nucleotides were also identified. The high frequency of pncA mutations observed in this study supports the usefulness of DNA-based detection of PZA-resistant M. tuberculosis. Having verified the scattered and diverse mutational characteristics of the pncA gene, automated DNA sequencing seems to be the best strategy for rapid detection of PZA-resistant M. tuberculosis.
Amidohydrolases/*genetics ; Antitubercular Agents/*pharmacology ; Drug Resistance, Bacterial ; *Mutation ; Mycobacterium tuberculosis/*drug effects/genetics ; Pyrazinamide/*pharmacology

Antitubercular Agents ; pharmacology ; Drug Resistance, Bacterial ; genetics ; Genotype ; Mycobacterium tuberculosis ; classification ; drug effects ; genetics

Aged ; China ; Drug Resistance, Bacterial ; Humans ; L Forms ; drug effects ; Middle Aged ; Mining ; Mutation ; Mycobacterium tuberculosis ; drug effects ; Silicotuberculosis ; microbiology

BACKGROUNDDrug susceptibility assay is very important in tuberculosis therapy. Pyrazinamide is a first line antituberculosis drug and diagnosis of its resistance in Mycobacterium tuberculosis (M. tuberculosis) is difficult and time consuming by conventional methods. In this study, we aimed to evaluate the performance of the microscopic observation drug susceptibility (MODS) assay in the detection of pyrazinamide resistance in M. tuberculosis relative to the conventional Wayne assay and Lowenstein-Jensen (LJ) proportion method.

METHODSM. tuberculosis clinical isolates (n = 132) were tested by the MODS and the Wayne assay: the results were compared with those obtained by the LJ proportion method. Mutations in the gene were identified by direct sequencing of the pncA genes of all isolates in which pyrazinamide resistance was detected by any of the three methods.

RESULTSCompared to the LJ results, the sensitivity and specificity of the MODS assay were 97.8% and 96.5% respectively; the sensitivity and specificity of the Wayne assay were 87.0% and 97.7% respectively. Mutations in the pncA gene were found in 41 of 46 strains that were pyrazinamide resistant (3 tests), in 1 of the 4 strains (LJ only), in 42 of 48 strains (at least 1 test), but no mutations in 1 strain sensitive according to the MODS assay only. The MODS assay, Wayne assay and LJ proportion method provided results in a median time of 6, 7 and 26 days respectively.

CONCLUSIONSMODS assay offers a rapid, simple and reliable method for the detection of pyrazinamide resistance in M. tuberculosis and is an optimal alternative method in resource limited countries.

Antitubercular Agents ; pharmacology ; Microbial Sensitivity Tests ; Microscopy ; methods ; Mycobacterium tuberculosis ; drug effects ; Pyrazinamide ; pharmacology

Anti-Bacterial Agents ; chemistry ; pharmacology ; Drug Resistance, Bacterial ; drug effects ; Humans ; Mycobacterium tuberculosis ; chemistry ; drug effects ; Tuberculosis, Multidrug-Resistant ; drug therapy ; microbiology

Objective: Drug-resistant tuberculosis (TB) may be resistant to one or multiple anti-TB drugs. We used generalized estimation equations to analysis the risk factors of drug-resistant TB and provide information for the establishment of a warning model for these non-independent data. Methods: The drug susceptibility test and questionnaire survey were performed in sputum positive TB patients from 30 anti TB drug-resistance surveillance sites in Zhejiang province. The generalized estimation model was established by the GENMOD module of SAS, with resistance to 13 kinds of anti-TB drugs as dependent variables and possible influencing factors, such as age, having insurance, HBV infection status, and history of anti-TB drug intake, as independent variables. Results: In this study, the probability of drug resistance at baseline level was 20.26%. Age, insurance, whether being co-infected with HBV, and treatment history or treatment withdrawal were statistically significantly correlated with anti-TB drug resistance. The prediction equation was established according to the influence degree of the factors mentioned above on drug resistance. Conclusion: The generalized estimation equations can effectively and robustly analyze the correlated binary outcomes, and thus provide more comprehensive information for drug resistance risk factor evaluation and warning model establishment.
Antitubercular Agents/therapeutic use* ; Drug Resistance, Multiple, Bacterial ; Humans ; Models, Statistical ; Mycobacterium tuberculosis/drug effects* ; Risk Factors ; Sputum/microbiology* ; Surveys and Questionnaires ; Tuberculosis/epidemiology* ; Tuberculosis, Multidrug-Resistant

Antitubercular Agents ; pharmacology ; Drug Resistance, Multiple, Bacterial ; genetics ; Humans ; Microbial Sensitivity Tests ; methods ; Mycobacterium tuberculosis ; drug effects ; genetics