Mycobacterium tuberculosis is a causative agent of tuberculosis (TB). The ability of M. tuberculosis to be quiescent in the cell has caused the emergence of latent infection. A comprehensive proteomic analysis of M. tuberculosis H37Rv over three growth phases, namely mid-log (14-day culture), early stationary (28-day culture), and late stationary (50-day culture), was performed in order to study the change in proteome from the mid-log phase to late-stationary phase. Combination methods of two-dimensional electrophoresis (2-DE) and tandem mass spectrometry were used to generate proteome maps of M. tuberculosis at different growth phases. Ten proteins were detected differentially expressed in the late-stationary phase compared with the other two phases. These proteins were SucD, TrpD, and Rv2161c, which belong to metabolic pathway proteins; FadE5, AccD5, DesA1, and Rv1139c are proteins involved in cell wall or lipid biosynthesis, whereas TB21.7 and Rv3224 are conserved hypothetical proteins with unknown function. A surface antigen protein, DesA1, was not detectable in the late-stationary phase, although present in both log and early-stationary phases. The changes in the expression levels of these proteins were in line with the growth environment changes of the bacteria from mid-log phase to late-stationary phase. The information gathered may be valuable in the intervention against latent TB infection.
Matched MeSH terms: Mycobacterium tuberculosis/growth & development
In this study, the susceptibility of Mycobacterium tuberculosis to isoniazid (INH) was compared with its derivative, 1-isonicotinyl-2-nonanoyl hydrazine (INH-C9), prepared synthetically. The minimum inhibitory concentration (MIC) of the drugs was determined using the 1% proportion method. INH-C9 was found to lower the MIC of INH from 0.05 to 0.025 microg/ml. Further studies on the effects of INH and INH-C9 on M. tuberculosis were assessed by exposing the cells to the above at the MIC level. M. tuberculosis cells grown on Middlebrook 7H10 agar were harvested at different stages of their growth cycle (initial stage, 24 and 72 h), exposed to the MICs of INH and INH-C9, and stained with acid-fast staining. The observations were made for a week. The cellular morphologies and staining characteristics were examined using a Brightfield microscope. The result indicated cells only at the initial stage of growth were most susceptible to the drugs resulting in the loss of acid-fastness and intact cellular morphology in the majority of cells.
Matched MeSH terms: Mycobacterium tuberculosis/growth & development
Indolizines are heteroaromatic compounds, and their synthetic analogues have reportedly showed promising pharmacological properties. In this study, a series of synthetic 7-methoxy-indolizine derivatives were synthesised, characterised and evaluated for in vitro whole-cell anti-tuberculosis (TB) screening against susceptible (H37Rv) and multi-drug-resistant (MDR) strains of Mycobacterium tuberculosis (MTB) using the resazurin microplate assay method. The cytotoxicity was evaluated using the MTT assay. In silico molecular-docking study was conducted for compounds 5a-j against enoyl-[acyl-carrier] protein reductase, a key enzyme of the type II fatty acid synthesis that has attracted much interest for the development of novel anti-TB compounds. Thereafter, molecular dynamic (MD) simulation was undertaken for the most active inhibitors. Compounds 5i and 5j with the methoxy functional group at the meta position of the benzoyl group, which was at the third position of the indolizine nucleus, demonstrated encouraging anti-TB activity against MDR strains of MTB at 16 μg/mL. In silico studies showed binding affinity within the range of 7.07-8.57 kcal/mol, with 5i showing the highest binding affinity. Hydrogen bonding, π-π- interactions, and electrostatic interactions were common with the active site. Most of these interactions occurred with the catalytic amino acids (Pro193, Tyr158, Phe149, and Lys165). MD simulation showed that 5j possessed the highest binding affinity toward the enzyme, according to the two calculation methods (MM/PBSA and MM/GBSA). The single-crystal X-ray studies of compounds 5c and 5d revealed that the molecular arrangements in these two structures were mostly guided by C-H···O hydrogen-bonded dimeric motifs and C-H···N hydrogen bonds, while various secondary interactions (such as π···π and C-H···F) also contributed to crystal formation. Compounds 5a, 5c, 5i, and 5j exhibited no toxicity up to 500 μg/mL. In conclusion, 5i and 5j are promising anti-TB compounds that have shown high affinity based on docking and MD simulation results.
A prospective study was conducted on 510 respiratory specimens for the presence of M. tuberculosis detected by direct acid-fast bacilli (AFB) smear examination, culture in the Manual Mycobacteria Growth Indicator Tube (BBL MGIT, Becton-Dickinson) and culture on Lowenstein-Jensen (LJ) medium. From positive BBL MGIT tubes, Ziehl-Neelsen and Gram stains were performed and subcultures were put up on LJ medium. A total of 101 (19.8%) specimens were positive by the BBL MGIT, 60 (11.8%) by primary LJ medium culture, 31 (6.1%) by direct smear examination and 29 (5.7%) by all three methods. Using primary LJ culture as the gold standard, the sensitivity and specificity of the BBL MGIT were 90% and 89.6% respectively but the sensitivity of AFB smear microscopy was only 48.3%. About half (51.1%) of the BBL MGIT false positives were due to contamination by non-AFB bacteria. The remaining false positives comprised specimens that were AFB microscopy positive but LJ culture negative. Of the AFB isolates obtained on LJ primary and sub-cultures, almost all (93.3%) were identified as Mycobacterium tuberculosis complex. The mean time-to-detection was significantly shorter (p < 0.0001) for the BBL MGIT than for LJ culture. For the former, positive results were available within 14 days for both AFB smear-positive and AFB smear-negative specimens. On the average, positive results were obtained 1.8 days earlier for direct AFB smear-positive samples than for AFB smear-negative samples. On the other hand, positive growth on LJ medium appeared after at least 33 days of incubation. These findings suggest that the BBL MGIT system will be a suitable alternative to LJ culture for the routine diagnosis of pulmonary tuberculosis, but a combination of liquid and solid cultures is still required for the highest diagnostic accuracy.
Matched MeSH terms: Mycobacterium tuberculosis/growth & development
This study was carried out to compare the performance of BACTEC MGIT 960 with the BACTEC 460 TB for growth and detection of Mycobacteria from human clinical specimens. The BACTEC MGIT 960 instrument is a fully automated system that utilizes MGIT tubes containing an oxygen sensor embedded in silicon at the bottom and filled with 7 mL of modified Middlebrook 7H9 broth. Identical samples were inoculated into the two automated systems and incubated for six weeks. Over a period of three months, 279 specimens were decontaminated and processed according to the standard CDC NALC/NaOH method, using the commercial MycoPrep kit. Forty-two specimens (15%) yielded Mycobacterium tuberculosis; 37 (88%) were detected by the fluorescent BACTEC MGIT 960 and 35 (83%) detected by the radiometric BACTEC 460 TB. Fifteen specimens (5%) yielded Mycobacterium Other Than Tuberculosis (MOTT); 10 (66%) were detected by BACTEC MGIT 960 and 11 (73%) detected by BACTEC 460 TB. The average time to detection and contamination rates and the average time to obtain results of antimicrobial susceptibility tests between the two systems were compared. The performance of the BACTEC MGIT 960 was comparable to the BACTEC 460 TB system which has been the "Gold Standard" for automated detection of TB. The former was more rapid, as sensitive and less labour intensive than the BACTEC 460. Our data demonstrates that the BACTEC MGIT 960 system is an accurate, automated and a non-radioactive alternative to the BACTEC 460 TB for the culture and susceptibility testing of M. tuberculosis.
Matched MeSH terms: Mycobacterium tuberculosis/growth & development
Various studies have reported culture conversion at two months as a predictor of successful treatment outcome in multidrug-resistant tuberculosis (MDR-TB).
Matched MeSH terms: Mycobacterium tuberculosis/growth & development
A series of some new bisadducts possessing five, six membered and coumarin subunits were synthesized by the condensation of heterocyclic aldehydes with active methylene compounds and characterized by IR, NMR and X-ray crystallographic studies and were assayed as antitubercular agents. Among the bisadducts, 4-hydroxy-3-[(4-hydroxy-2-oxo-2H-3-chromenyl)(3-thienyl)methyl]-2H-2-chromenone 3a was found to be the most promising compound, active against Mycobacterium tuberculosis (Mtb) H37Rv and isoniazid resistant Mycobacterium tuberculosis (INHR-Mtb) with minimum inhibitory concentration 5.22 and 8.34 microM, respectively.
Matched MeSH terms: Mycobacterium tuberculosis/growth & development
The chemotherapy for tuberculosis (TB) is complicated by its long-term treatment, its frequent drug dosing, and the adverse effects of anti-TB drugs. In this study, we have developed two nanocomposites (A and B) by intercalating the anti-TB drug isoniazid (INH) into Zn/Al-layered double hydroxides. The average size of the nanocomposites was found to bê164 nm. The efficacy of the Zn/Al-layered double hydroxides intercalated INH against Mycobacterium tuberculosis was increased by approximately three times more than free INH. The nanocomposites were also found to be active against Gram-positive and -negative bacteria. Compared to the free INH, the nanodelivery formulation was determined to be three times more biocompatible with human normal lung fibroblast MRC-5 cells and 3T3 fibroblast cells at a very high concentration of 50 µg/mL for up to 72 hours. The in vitro release of INH from the Zn/Al-layered double hydroxides was found to be sustained in human body-simulated buffer solutions of pH 4.8 and 7.4. This research is a step forward in making the TB chemotherapy patient friendly.
Matched MeSH terms: Mycobacterium tuberculosis/growth & development
Tuberculosis (TB) remains an important cause of mortality and morbidity. The TB vaccine, BCG, is not fully protective against the adult form of the disease and is unable to prevent its transmission although it is still useful against severe childhood TB. Hence, the search for new vaccines is of great interest. In a previous study, we have shown that proteoliposomes obtained from Mycobacterium smegmatis (PLMs) induced cross reactive humoral and cellular response against Mycobacterium tuberculosis (Mtb) antigens. With the objective to evaluate the protective capability of PLMs, a murine model of progressive pulmonary TB was used. Animals immunized with PLMs with and without alum (PLMs/PLMsAL respectively) showed protection compared to non-immunized animals. Mice immunized with PLMsAL induced similar protection as that of BCG. Animals immunized with BCG, PLMs and PLMsAL showed a significant decrease in tissue damage (percentage of pneumonic area/lung) compared to non-immunized animals, with a more prominent effect in BCG vaccinated mice. The protective effect of the administration of PLMs in mice supports its future evaluation as experimental vaccine candidate against Mtb.
Matched MeSH terms: Mycobacterium tuberculosis/growth & development