Mycobacterium Tuberculosis Strains Research Articles

A Study of Embryotoxic, Foetotoxic, and Teratogenic Effects of the Original Antituberculosis Agent Thiozonide in Pregnant Rabbits

Several treatment regimens with antituberculosis medicinal products are available for tuberculosis. Thiozonide is a newly developed original antimicrobial agent that exhibits bacteriostatic activity against Mycobacterium tuberculosis strains H37Rv, CN-37, CN-40, and MS-115.The aim of the study was to investigate the embryotoxic, foetotoxic, and teratogenic effects of thiozonide in pregnant rabbits.Materials and methods. The study involved 66 pregnant rabbits (4 groups of 16–17 animals each). The rabbits received oral thiozonide from day 6 to day 19 of gestation at doses of 20.6 mg/kg (1 TD (therapeutic dose)), 103 mg/kg (5 TDs), and 206 mg/kg (10 TDs). The control group received a 1% starch solution. The authors conducted a macroscopic examination of the reproductive organs and a histological evaluation of the placenta in eutha nised pregnant rabbits. Live foetuses underwent a check for developmental abnormalities, a skeletal development evaluation with a modified Dawson’s method, and a histologic examination of the internal organs.Results. The study showed no clinical signs of toxicity and no mortality associated with thiozonide in pregnant rabbits across all dose groups. Macroscopic and histological examinations revealed no pathological changes in the reproductive organs of pregnant rabbits. The evaluation of embryotoxic and foetotoxic effects did not identify any differences between the foetuses of the animals assigned to different doses of thiozonide and the control group. The authors found no developmental abnormalities in the foetuses. Examinations of foetal skeleton development and internal organ condition identified no differences between the groups and no abnormalities. The authors registered the death of all foetuses (late resorption) in one rabbit from the 206 mg/kg group. Therefore, the 103 mg/kg dose (5 TDs) was selected as a reasonable No Observed Adverse Effect Level (NOAEL).Conclusions. Thiozonide has no embryotoxic, foetotoxic, or teratogenic effects.

Tetrahydrobenzo[h]quinoline derivatives as a novel chemotype for dual antileishmanial-antimalarial activity graced with antitubercular activity: Design, synthesis and biological evaluation

Derivatives with tetrahydrobenzo[h]quinoline chemotype were synthesized via one-pot reactions and evaluated for their antileishmanial, antimalarial and antitubercular activities. Based on a structure-guided approach, they were designed to possess antileishmanial activity through antifolate mechanism, via targeting Leishmania major pteridine reductase 1 (Lm-PTR1). The in vitro antipromastigote and antiamastigote activity are promising for all candidates and superior to the reference miltefosine, in a low or sub micromolar range of activity. Their antifolate mechanism was confirmed via the ability of folic and folinic acids to reverse the antileishmanial activity of these compounds, comparably to Lm-PTR1 inhibitor trimethoprim. Molecular dynamics simulations confirmed a stable and high potential binding of the most active candidates against leishmanial PTR1. For the antimalarial activity, most of the compounds exhibited promising antiplasmodial effect against P. berghei with suppression percentage of up to 97.78%. The most active compounds were further screened in vitro against the chloroquine resistant strain P. falciparum, (RKL9) and showed IC50 value range of 0.0198–0.096 μM, compared to IC50 value of 0.19420 μM for chloroquine sulphate. Molecular docking of the most active compounds against the wild-type and quadruple mutant pf DHFR-TS structures rationalized the in vitro antimalarial activity. Some candidates showed good antitubercular activity against sensitive Mycobacterium tuberculosis in a low micromolar range of MIC, compared to 0.875 μM of isoniazid. The top active ones were further tested against a multidrug-resistant strain (MDR) and extensively drug-resistant strain (XDR) of Mycobacterium tuberculosis. Interestingly, the in vitro cytotoxicity test of the best candidates displayed high selectivity indices emphasizing their safety on mammalian cells. Generally, this work introduces a fruitful matrix for new dual acting antileishmanial-antimalarial chemotype graced with antitubercular activity. This would help in tackling drug-resistance issues in treating some Neglected Tropical Diseases.

Metabolomic analysis of Mycobacterium tuberculosis reveals metabolic profiles for identification of drug-resistant tuberculosis

The detection of pre-extensively (pre-XDR) and extensively drug-resistant tuberculosis (XDR-TB) is challenging. Drug-susceptibility tests for some anti-TB drugs, especially ethambutol (ETH) and ethionamide (ETO), are problematic due to overlapping thresholds to differentiate between susceptible and resistant phenotypes. We aimed to identify possible metabolomic markers to detect Mycobacterium tuberculosis (Mtb) strains causing pre-XDR and XDR-TB. The metabolic patterns of ETH- and ETO-resistant Mtb isolates were also investigated. Metabolomics of 150 Mtb isolates (54 pre-XDR, 63 XDR-TB and 33 pan-susceptible; pan-S) were investigated. Metabolomics of ETH and ETO phenotypically resistant subgroups were analyzed using UHPLC-ESI-QTOF-MS/MS. Orthogonal partial least-squares discriminant analysis revealed distinct separation in all pairwise comparisons among groups. Two metabolites (meso-hydroxyheme and itaconic anhydride) were able to differentiate the pre-XDR and XDR-TB groups from the pan-S group with 100% sensitivity and 100% specificity. In comparisons of the ETH and ETO phenotypically resistant subsets, sets of increased (ETH = 15, ETO = 7) and decreased (ETH = 1, ETO = 6) metabolites specific for the resistance phenotype of each drug were found. We demonstrated the potential for metabolomics of Mtb to differentiate among types of DR-TB as well as between isolates that were phenotypically resistant to ETO and ETH. Thus, metabolomics might be further applied for DR-TB diagnosis and patient management.

Synthesis, antitubercular profile and molecular docking studies of quinazolinone-based pyridine derivatives against drug-resistant tuberculosis

The promising quinazolinone-based pyridine derivatives (4a–j) were synthesized and subsequently tested for their antimycobacterial activities against the various drug-sensitive and drug-resistant Mycobacterium tuberculosis (Mtb) strains to combat infectious diseases and address growing concerns about the devastating effects of tuberculosis (TB). Utilizing 1H NMR, 13C NMR, and mass spectra, the structural and molecular confirmation of the synthesized compounds were deciphered. With minimum inhibitory concentration (MIC) values ranging from 0.31 to 19.13 μM, the results showed that compounds 4e and 4f showed promise anti-TB action against both drug-sensitive and drug-resistant TB strains. To study the cytotoxicity of synthesized molecules, normal Vero and mouse macrophage (RAW264.7) cell lines were utilized. Remarkably, it was revealed that at the highest concentration tested, none of the newly synthesized molecules were toxic to the Vero cell line. The binding patterns of the potent compounds 4b, 4e and 4f in the active site of the mycobacterial membrane protein Large 3 (MmpL3) protein are also revealed by molecular docking studies, which has contributed to the development of a structural rationale for Mtb inhibition. The physicochemical characteristics of the compounds were then predicted using theoretical calculations. Overall, the molecular docking results, physiochemical properties, and observed antimycobacterial activity all point to compound 4e with trifluoromethyl and compound 4f with nitro moiety as potential quinazolinone linked pyridine-based MmpL3 inhibitors. Communicated by Ramaswamy H. Sarma

Beneficial or detrimental activity of regulatory T cells, indoleamine 2,3-dioxygenase, and heme oxygenase-1 in the lungs is influenced by the level of virulence of Mycobacterium tuberculosis strain infection.

Tuberculosis (TB) caused by the complex Mycobacterium tuberculosis (Mtb) is the main cause of death by a single bacterial agent. Last year, TB was the second leading infectious killer after SARS-CoV-2. Nevertheless, many biological and immunological aspects of TB are not completely elucidated, such as the complex process of immunoregulation mediated by regulatory T cells (Treg cells) and the enzymes indoleamine 2,3-dioxygenase (IDO) and heme oxygenase 1 (HO-1). In this study, the contribution of these immunoregulatory factors was compared in mice infected with Mtb strains with different levels of virulence. First Balb/c mice were infected by intratracheal route, with a high dose of mild virulence reference strain H37Rv or with a highly virulent clinical isolate (strain 5186). In the lungs of infected mice, the kinetics of Treg cells during the infection were determined by cytofluorometry and the expression of IDO and HO-1 by RT-PCR and immunohistochemistry. Then, the contribution of immune-regulation mediated by Treg cells, IDO and HO-1, was evaluated by treating infected animals with specific cytotoxic monoclonal antibodies for Treg cells depletion anti-CD25 (PC61 clone) or by blocking IDO and HO-1 activity using specific inhibitors (1-methyl-D,L-tryptophan or zinc protoporphyrin-IX, respectively). Mice infected with the mild virulent strain showed a progressive increment of Treg cells, showing this highest number at the beginning of the late phase of the infection (28 days), the same trend was observed in the expression of both enzymes being macrophages the cells that showed the highest immunostaining. Animals infected with the highly virulent strain showed lower survival (34 days) and higher amounts of Treg cells, as well as higher expression of IDO and HO-1 one week before. In comparison with non-treated animals, mice infected with strain H37Rv with depletion of Treg cells or treated with the enzymes blockers during late infection showed a significant decrease of bacilli loads, higher expression of IFN-g and lower IL-4 but with a similar extension of inflammatory lung consolidation determined by automated morphometry. In contrast, the depletion of Treg cells in infected mice with the highly virulent strain 5186 produced diffuse alveolar damage that was similar to severe acute viral pneumonia, lesser survival and increase of bacillary loads, while blocking of both IDO and HO-1 produced high bacillary loads and extensive pneumonia with necrosis. Thus, it seems that Treg cells, IDO and HO-1 activities are detrimental during late pulmonary TB induced by mild virulence Mtb, probably because these factors decrease immune protection mediated by the Th1 response. In contrast, Treg cells, IDO and HO-1 are beneficial when the infection is produced by a highly virulent strain, by regulation of excessive inflammation that produced alveolar damage, pulmonary necrosis, acute respiratory insufficiency, and rapid death.

Genomic characteristics of Mycobacterium tuberculosis isolates of cutaneous tuberculosis.

Cutaneous tuberculosis with various manifestations can be divided into several clinical types according to the host's immune status and infective route. However, the etiological factors of this disease remain unclear. The objective of this study is to investigate the pathogens associated with the occurrence and different types of cutaneous tuberculosis. 58 Mycobacterium tuberculosis strains isolated from cutaneous tuberculosis over the last 20 years were sequenced and analyzed for genomic characteristics including lineage distribution, drug-resistance mutations, and mutations potentially associated with different sites of infection. The M. tuberculosis strains from four major types of cutaneous tuberculosis and pulmonary tuberculosis shared similar genotypes and genomic composition. The strains isolated from cutaneous tuberculosis had a lower rate of drug resistance. Phylogenic analysis showed cutaneous tuberculosis and pulmonary tuberculosis isolates scattered on the three. Several SNPs in metabolism related genes exhibited a strong correlation with different infection sites. The different infection sites of TB may barely be affected by large genomic changes in M. tuberculosis isolates, but the significant difference in SNPs of drug resistance gene and metabolism-related genes still deserves more attention.

Transmission of Mycobacterium tuberculosis in schools: a molecular epidemiological study using whole-genome sequencing in Guangzhou, China.

China is a country with a high burden of tuberculosis (TB). TB outbreaks are frequent in schools. Thus, understanding the transmission patterns is crucial for controlling TB. In this genomic epidemiological study, the conventional epidemiological survey data combined with whole-genome sequencing was used to assess the genotypic distribution and transmission characteristics of Mycobacterium tuberculosis strains isolated from patients with TB attending schools during 2015 to 2019 in Guangzhou, China. The TB incidence was mainly concentrated in regular secondary schools and technical and vocational schools. The incidence of drug resistance among the students was 16.30% (22/135). The phylogenetic tree showed that 79.26% (107/135) and 20.74% (28/135) of the strains belonged to lineage 2 (Beijing genotype) and lineage 4 (Euro-American genotype), respectively. Among the 135 isolates, five clusters with genomic distance within 12 single nucleotide polymorphisms were identified; these clusters included 10 strains, accounting for an overall clustering rate of 7.4% (10/135), which showed a much lower transmission index. The distance between the home or school address and the interval time of symptom onset or diagnosis indicated that campus dissemination and community dissemination may be existed both, and community dissemination is the main. TB cases in Guangzhou schools were mainly disseminated and predominantly originated from community transmission. Accordingly, surveillance needs to be strengthened to stop the spread of TB in schools.

C-1 Substituted isoquinolines potentiate the antimycobacterial activity of rifampicin and ethambutol

IntroductionThe emergence of extensively drug-resistant strains ofMycobacterium tuberculosisthreatens decades of progress in the treatment of a disease which remains one of the leading infectious causes of death worldwide. The development of novel antimycobacterial compounds is therefore essential to reinforce the existing antitubercular drug discovery pipeline. There is also interest in new compounds which can synergize with existing antitubercular drugs and can be deployed as part of a combination therapy. This strategy could serve to delay the emergence of resistance to first-line anti-tuberculosis drugs and increase their efficacy against resistant strains of tuberculosis. Previous research has established that several C-1 substituted tetrahydroisoquinolines have antimycobacterial activity. Here we sought to expand our understanding of their antimycobacterial structure activity relationships and their potential to act as adjunct therapies alongside existing antitubercular drugs.MethodsThree chemical series were synthesised and assayed for their antimycobacterial potency, mammalian cell toxicity, inhibition of whole-cell efflux and synergism with isoniazid, rifampicin, and ethambutol.ResultsSeveral compounds were found to inhibit the growth of mycobacteria. Potent inhibitors of whole-cell efflux were also identified, as well as compounds which exhibited synergism with rifampicin and ethambutol.ConclusionsStructure-activity relationships were identified for antimycobacterial potency, improved selectivity, whole cell efflux inhibition and synergism. Potent whole-cell efflux inhibitors and synergistic compounds were identified, suggesting potential development as adjuncts to existing anti-tuberculosis chemotherapy.

BCG∆BCG1419c and BCG differ in induction of autophagy, c-di-GMP content, proteome, and progression of lung pathology in Mycobacterium tuberculosis HN878-infected male BALB/c mice

The efficacy of BCG vaccines against Mycobacterium tuberculosis (Mtb) strains of lineage 2 (Beijing) in preclinical models and humans has been questioned. We have developed BCG∆BCG1419c, by deletion of BCG1419c in BCG Pasteur, which improved control of tuberculosis (TB) in preclinical models. Here, we compared the capacity of BCG and BCG∆BCG1419c to induce autophagy in murine macrophages, modify c-di-GMP content and transcript levels of BCG1416c, encoding the enzyme responsible for c-di-GMP synthesis/degradation, and of BCG1419c, encoding the phosphodiesterase involved in c-di-GMP degradation. Furthermore, we evaluated proteomic differences in vitro and compared protection against TB produced by a low dose of the HN878-Beijing strain at 3- and 6-months post-infection. We found that BCG∆BCG1419c induced more autophagy and produced different levels of c-di-GMP as well as different transcription of BCG1416c with no expression of BCG1419c. BCG∆BCG1419c differentially produced several proteins, including some involved in interaction with host cells. Vaccination with either BCG strain led to control of bacillary burden in lungs and spleen at 3- but not 6-months post-infection, whereas it reduced pneumonic areas compared with unvaccinated controls at 6 months post-infection. Vaccination with BCG∆BCG1419c delayed progression of lung necrosis as this was observed only at 6 months post-infection. Taken together, compared with BCG, BCG∆BCG1419c increased autophagy, presented different levels of c-di-GMP and transcription of BCG1416c in vitro in a growth-phase dependent manner, modified its proteome and delayed progression of lung pathology produced by a highly virulent Beijing strain.

Isatin-pyrimidine hybrid derivatives as enoyl acyl carrier protein reductase (InhA) inhibitors against Mycobacterium tuberculosis

Tuberculosis is a worldwide problem that impose a burden on the economy due to continuous development of resistant strains. The development of new antitubercular drugs is a need and can be achieved through inhibition of druggable targets. Mycobacterium tuberculosis enoyl acyl carrier protein (ACP) reductase (InhA) is an important enzyme for Mycobacterium tuberculosis survival. In this study, we report the synthesis of isatin derivatives that could treat TB through inhibition of this enzyme. Compound 4l showed IC50 value (0.6 ± 0.94 µM) similar to isoniazid but is also effective against MDR and XDR Mycobacterium tuberculosis strains (MIC of 0.48 and 3.9 µg/mL, respectively). Molecular docking studies suggest that this compound binds through the use of relatively unexplored hydrophobic pocket in the active site. Molecular dynamics was used to investigate and support the stability of 4l complex with the target enzyme. This study paves the way for the design and synthesis of novel antitubercular drugs.

Kinetic and structural studies of Mycobacterium tuberculosis dihydroorotate dehydrogenase reveal new insights into class 2 DHODH inhibition

Tuberculosis (TB) is a leading cause of death worldwide. TB represents a serious public health threat, and it is characterized by high transmission rates, prevalence in impoverished regions, and high co-infection rates with HIV. Moreover, the serious side effects of long-term treatment that decrease patient adherence, and the emergence of multi-resistant strains of Mycobacterium tuberculosis, the causing agent of TBs, pose several challenges for its eradication. The search for a new TB treatment is necessary and urgent. Dihydroorotate dehydrogenase (DHODH) is responsible for the stereospecific oxidation of (S)-dihydroorotate (DHO) to orotate during the fourth and only redox step of the de novo pyrimidine nucleotide biosynthetic pathway. DHODH has been considered an attractive target against infectious diseases. As a first step towards exploiting DHODH as a drug target against TB, we performed a full kinetic characterization of both bacterial MtDHODH and its human ortholog (HsDHDOH) using both substrates coenzyme Q0 (Q0) and vitamin K3 (K3). MtDHODH follows a ping-pong mechanism of catalysis and shares similar catalytic parameters with the human enzyme. Serendipitously, Q0 was found to inhibit MtDHODH (KI (Q0) = 138 ± 31 μM). To the best of our knowledge, Q0 is the first non-orotate like dihydroorotate-competitive inhibitor for class 2 DHODHs ever described. Molecular dynamics simulations along with in silico solvent mapping allowed us to successfully probe protein flexibility and correlate it with the druggability of binding sites. Together, our results provide the starting point for the design of a new generation of potent and selective inhibitors against MtDHODH.

Epidemiological manifestations of tuberculosis infection in the Omsk region: dynamics and trends

Background. Tuberculosis (TB) infection remains relevant as one of the leading public health problems in Russia.The aim. To characterize the dynamics and trends of epidemiological manifestations of TB infection in the Omsk region.Materials and methods. An observational descriptive-evaluative epidemiological study was carried out in the Omsk region from 2009 to 2021. The data available in the Federal statistical observation forms NN 7, 8, and 33, and results of the bacteriological study of patients with respiratory TB were analyzed.Results. In the Omsk region, an improvement in the epidemiological situation was observed from 2009 to 2021. It was associated with a decrease in TB prevalence by 3.7 times (from 325.6 to 86.7), mortality – by 5.8 times (from 21.1 to 3.6), incidence – by 2.7 times (from 130.7 to 48.4 per 100,000). At the same time, proportion of microscopy/culture-positive patients infected with multidrug-resistant Mycobacterium tuberculosis strains increased from 9.2 to 29.8 % among all patients, and from 15.5 to 30.6 % among newly diagnosed patients. There was a trend towards an increase in the number of cases with primary extensive drug resistance of M. tuberculosis. The incidence of tuberculosis associated with HIV infection has increased 10 times and reached 15.6 per 100,000 population.Conclusions. In the Omsk region, there is a change in the structure of M. tuberculosis strains with a predominance of multiple and extensive drug resistance along with decrease in TB incidence and mortality. New approaches are needed to organize the system of epidemiological surveillance and control of TB infection.

The mutational signatures of poor treatment outcomes on the drug-susceptible Mycobacterium tuberculosis genome.

Drug resistance is a known risk factor for poor tuberculosis (TB) treatment outcomes, but the contribution of other bacterial factors to poor outcomes in drug-susceptible TB is less well understood. Here, we generate a population-based dataset of drug-susceptible Mycobacterium tuberculosis (MTB) isolates from China to identify factors associated with poor treatment outcomes. We analyzed whole-genome sequencing (WGS) data of MTB strains from 3196 patients, including 3105 patients with good and 91 patients with poor treatment outcomes, and linked genomes to patient epidemiological data. A genome-wide association study (GWAS) was performed to identify bacterial genomic variants associated with poor outcomes. Risk factors identified by logistic regression analysis were used in clinical models to predict treatment outcomes. GWAS identified fourteen MTB fixed mutations associated with poor treatment outcomes, but only 24.2% (22/91) of strains from patients with poor outcomes carried at least one of these mutations. Isolates from patients with poor outcomes showed a higher ratio of reactive oxygen species (ROS)-associated mutations compared to isolates from patients with good outcomes (26.3% vs 22.9%, t-test, p=0.027). Patient age, sex, and duration of diagnostic delay were also independently associated with poor outcomes. Bacterial factors alone had poor power to predict poor outcomes with an AUC of 0.58. The AUC with host factors alone was 0.70, but increased significantly to 0.74 (DeLong's test, p=0.01) when bacterial factors were also included. In conclusion, although we identified MTB genomic mutations that are significantly associated with poor treatment outcomes in drug-susceptible TB cases, their effects appear to be limited.

The nature of the stimulant differentially impacts the innate memory response of monocytes to Mycobacterium tuberculosis

Abstract Innate immune cells, such as monocytes, can generate a non-specific ‘memory’ response (a.k.a. trained immunity) upon stimulation with an antigen/bacterium (e.g., LPS or BCG), which confers heterologous protection against another infectious agent. However, the association between the nature of stimulants and the corresponding immune correlate of trained immunity is not fully understood. Similarly, the response of macrophages “trained” by various stimulants to subsequent infection by different clinical Mycobacterium tuberculosis(Mtb) strains remains unknown. Here, we report the trained immunity profile of the blood-derived monocytes (BDM) of BCG-vaccinated adults and monocytic THP-1 cells after stimulation with BCG, LPS, Purified Protein Derivative (PPD), heat-killed MtbHN878 or MtbCDC1551 strains. The response of monocytes trained by these agents to subsequent infection with clinical Mtb isolates HN878 and CDC1551, which differ in their virulence potential, was evaluated using standard molecular and cellular immunologic assays. The BCG- and LPS-trained macrophages produced higher proinflammatory, antimicrobial responses, and autophagy induction than unstimulated, PPD, HK-HN878, or CDC1551-stimulated cells. The HN878-infected trained THP-1 cells elicited a more robust inflammatory response than the CDC1551 infection. A significantly reduced intracellular Mtb growth was noted in the BCG and LPS-trained THP-1 cells, which was augmented by adding rapamycin, an autophagy inducer. A similar immunological response was noted in the BDM of BCG-vaccinated adults infected with these Mtb strains. Thus, the nature of the stimulant affects the macrophages’ trained immunity profile and its response to Mtb infection. Supported by grants from NIH (R01 AI161822) and the Bill and Melinda Gates Foundation (INV-009099; formerly OPP1157210).

Comprehensive Drug Resistance Characterization of Pulmonary Tuberculosis in Algeria: Insights on Mycobacterium tuberculosis Strains by Whole-Genome Sequencing.

In this study, we aimed to characterize drug-resistant strains by whole-genome sequencing (WGS), to describe the spreading lineages and the history of transmission. Drug susceptibility testing was performed by 96-well broth microdilution plates. The genomic DNA was extracted and purified; libraries were prepared and run on the Illumina NextSeq500 System. Among 82 isolates, 21 tuberculosis (TB) isolates (25.6%) were drug resistant, including 10 MDR and 4 pre-extensively drug-resistant (XDR)-TB. The mutation Ser315Thr in the katG gene was confirmed in 15 isolates. In rpoB, Ser450Leu and His445Asp mutations were the most common. Asp94Asn and Ala90Val mutations were reported in gyrA. The LAM family, the most TB drug resistant, was widely predominant in the north and the T sublineage in the south of the country. This study provides the first insight on TB drug resistance using WGS in Algeria and clearly describes the first pre-XDR-TB cases and lineage distribution across the country.

The relative transmission fitness of multidrug-resistant Mycobacterium tuberculosis in a drug resistance hotspot

Multidrug-resistant tuberculosis (MDR-TB) is among the most frequent causes of death due to antimicrobial resistance. Although only 3% of global TB cases are MDR, geographical hotspots with up to 40% of MDR-TB have been observed in countries of the former Soviet Union. While the quality of TB control and patient-related factors are known contributors to such hotspots, the role of the pathogen remains unclear. Here we show that in the country of Georgia, a known hotspot of MDR-TB, MDR Mycobacterium tuberculosis strains of lineage 4 (L4) transmit less than their drug-susceptible counterparts, whereas most MDR strains of L2 suffer no such defect. Our findings further indicate that the high transmission fitness of these L2 strains results from epistatic interactions between the rifampicin resistance-conferring mutation RpoB S450L, compensatory mutations in the RNA polymerase, and other pre-existing genetic features of L2/Beijing clones that circulate in Georgia. We conclude that the transmission fitness of MDR M. tuberculosis strains is heterogeneous, but can be as high as drug-susceptible forms, and that such highly drug-resistant and transmissible strains contribute to the emergence and maintenance of hotspots of MDR-TB. As these strains successfully overcome the metabolic burden of drug resistance, and given the ongoing rollout of new treatment regimens against MDR-TB, proper surveillance should be implemented to prevent these strains from acquiring resistance to the additional drugs.

Antimicrobial Peptides: A Promising Strategy for Anti-tuberculosis Therapeutics.

The high global burden of tuberculosis (TB) and the increasing emergence of the drugresistant (DR) strain of Mycobacterium tuberculosis (Mtb) emphasize the urgent need for novel antimycobacterial agents. Antimicrobial peptides (AMPs) are small peptides widely existing in a variety of organisms and usually have amphiphilic cationic structures, which have a selective affinity to the negatively charged bacterial cell wall. Besides direct bactericidal mechanisms, including interacting with the bacterial cell membrane and interfering with the biosynthesis of the cell wall, DNA, or protein, some AMPs are involved in the host's innate immunity. AMPs are promising alternative or complementary agents for the treatment of DR-TB, given their various antibacterial mechanisms and low cytotoxicity. A large number of AMPs, synthetic or natural, from human to bacteriophage sources, have displayed potent anti-mycobacterial activity in vitro and in vivo. In this review, we summarized the features, antimycobacterial activity, and mechanisms of action of the AMPs according to their sources. Although AMPs have not yet met the expectations for clinical application due to their low bioavailabilities, high cost, and difficulties in large-scale production, their potent antimycobacterial activity and action mechanisms, which are different from conventional antibiotics, make them promising antibacterial agents against DR-Mtb in the future.

Molecular detection and phylogeography of the hypervirulent subtype of <i>Mycobacterium tuberculosis</i> Beijing 14717-15

Aim. To develop a method for detecting Mycobacterium tuberculosis strains belonging to highly lethal, hypervirulent, multidrug-resistant Beijing 14717-15-cluster to be applied to screen for M. tuberculosis retrospective collections obtained from various regions of Russia. The collection included M. tuberculosis DNA samples obtained during population studies. Spoligotyping and genotyping of 24 variable number tandem repeats loci were performed according to standard protocols. Phylogenetic analysis was based on the whole genome sequencing data. Polymorphism at the genomic position 2423040 A G, specific for the Beijing 14717-15 cluster, was detected using PCR-RFLP and HhaI restriction enzyme. The bioinformatic and phylogenetic analysis of whole genome sequencing data for 205 strains of the early ancient sublineage of the M. tuberculosis Beijing genotype showed that strains with the VNTR 14717-15 profile (according to MIRU-VNTRplus.org) and those close to it were grouped into one monophyletic cluster of related strains, which we defined as Beijing 14717-15-cluster. Among the SNPs specific for the 14717-15 cluster, we chose a functionally neutral SNP at the genomic position 2423040 A G (Rv2161c Val33Ala) and developed a method for its detection in the PCR-RFLP format. Next, we applied this method to screening DNA collections from the regions of the European and Asian parts of Russia and Asian countries. The data demonstrate the presence of strains of the Beijing 14717-15 cluster only in the Asian region of Russia peaking in Buryatia (18%). We have developed a method for detection of the hypervirulent and highly lethal genetic cluster M. tuberculosis Beijing 14717-15 based on detection of the specific mutation in the Rv2161c gene using PCR followed by HhaI restriction of the PCR product and agarose gel electrophoresis to discriminate between wild-type and mutant alleles. The advantages of the proposed method are the speed, simple and unambiguous data interpretation, opportunity to detect contamination and mixed infection, suitability for efficient analysis of large collections of M. tuberculosis strains.

Strain identification of Mycobacterium tuberculosis in multidrug-resistant tuberculosis (MDR-TB) patients at Undata Hospital, Palu, Central Sulawesi

MDR-TB is a tuberculosis disease resistant to the two most effective anti-TB drugs, rifampin and isoniazid. MDR-TB is a threat to TB control. This study aims to identify the Mycobacterium tuberculosis strain in MDR-TB patients at Undata Hospital in Palu, Central Sulawesi. This type of research is descriptive and observational with a cross-sectional design. The study was conducted in Palu City, Donggala Regency, and Sigi Regency from April–June 2021. The sample in this study consisted of 22 patients who had undergone MDR-TB treatment from 2019 to 2020. The results showed that 55% of the patients with MDR-TB lived in Palu City, 27% in Donggala Regency, and 18% in Sigi Regency. Out of the 22 patients, 13 were men (59%) and nine were women (41%). Based on the results of the examination of Mycobacterium tuberculosis culture, three samples from patients with MDR-TB were positive for M. tuberculosis. The results of the spoligotyping examination showed that the strain belonged to the Beijing family. Identifying the type of M. tuberculosis strain through spoligotyping examination should be carried out in TB patients who have not undergone MDR-TB treatment or those who have failed treatment and are still found to be positive for M. tuberculosis bacteria.

Mutation in the Rifampicin Resistance Region in Mycobacterium Tuberculosis in Guinea

Introduction: In recent years, strains of Mycobacterium tuberculosis resistant to rifampicin have become frequently encountered in Guinea. This fact is regularly notified since the installation of GeneXpert automatons in hospital structures in Conakry and in the capital of the administrative regions as well as the various prefectures of Guinea. Objective: The aim of this present study was to determine the rifampicin resistance profiles of Mycobacterium tuberculosis strains at the Pneumophtisiology Department of the Ignace Deen National Hospital of Conakry. Methods: We conducted a retrospective and analytical study lasting 22 months from January 2017 to June 2018 then from April to July 2019 on the files of patients received at the National Reference Laboratory for Mycobacteria of the Ignace Deen National Hospital of Conakry for examinations of samples on the GeneXpert. Results: In 325 cases of rifampicin resistance, we found mutations associated with region E (42.15%), region D (35.38%), region B (15.08%), region A (1.53%) and that of C (0.92%). We also observed multiple mutations A-B (0.92%), A-D (3.69%), D-E (0.30%). Conclusion: The proportion of E probes was the highest followed by D probes then B probes (512-518). We encountered multiple mutations, like A-B, A-D, D-E.