Forms Of Mycobacterium Tuberculosis Research Articles

Compensatory mutations as a mechanism for preserving virulence and viability of drug-resistant forms of Mycobacterium tuberculosis

Compensatory mutations as a mechanism for preserving virulence and viability of drug-resistant forms of Mycobacterium tuberculosis

Pharmacophore modeling of pretomanid (PA-824) derivatives for antitubercular potency against replicating and non-replicating Mycobacterium tuberculosis

Pretomanid (PA-824) is the recently (2019) approved drug for the treatment of extensively drug-resistant (XDR) TB and the multidrug-resistant (MDR) TB by US FDA. The experimental data of antitubercular activity of 543 pretomanid derivatives (total 6 datasets) against replicating (active) and non-replicating (dormant) forms of Mycobacterium tuberculosis (strain H37Rv) are available in the literature. Such vast experimental data of pretomanid derivatives against both of these endpoints, and recent approval of pretomanid molecule as a drug encouraged us to utilize this existing experimental information for the development of the 3D-pharmacophore models. The developed model (Hypo-1, MABA) showed the three physicochemical features namely, the oxygen atom of nitro group (HBA_1), fused pyran ring of imidazopyran heterocycle (HYAl_2) and the 4-fluorophenyl moiety (HYAr_3) are crucial for the antitubercular activity against replicating M. tb. Subsequently, the pharmacophore model (Hypo-1, LORA) developed against the non-replicating form of M. tb also showed the contribution of three physicochemical features namely, the 4-tri-fluoromethyl group (HYAl_2) and both the phenyl groups (HYAr_3, HYAr_4) of biaryl moiety in increasing the antitubercular activity. Both the pharmacophoric classifier models showed the classification accuracies of 82.98 and 74.42% for the training set compounds, and 63.91 and 61.60% for the test set compounds respectively, for labelling the compounds into higher and lower active classes. Both the models were also found to be retaining the higher active compounds in top 1.00% of the total number of compounds (decoys and actives), after performing the decoy set screening. Communicated by Ramaswamy H. Sarma

Protein Kinases A (PknA), a Good Target for Vaccine Design against Tuberculosis

The tuberculosis (Tb) pandemic continues to rampage despite widespread use of the bacillus Calmette-Guerin vaccine. Novel vaccination strategies are urgently needed to arrest global transmission and prevent the uncontrolled development of multidrug-resistant forms of Mycobacterium tuberculosis.

A Repeating Sulfated Galactan Motif Resuscitates Dormant Micrococcus luteus Bacteria.

Only a small fraction of bacteria can autonomously initiate growth on agar plates. Nongrowing bacteria typically enter a metabolically inactive dormant state and require specific chemical trigger factors or signals to exit this state and to resume growth. Micrococcus luteus has become a model organism for this important yet poorly understood phenomenon. Only a few resuscitation signals have been described to date, and all of them are produced endogenously by bacterial species. We report the discovery of a novel type of resuscitation signal that allows M. luteus to grow on agar but not agarose plates. Fractionation of the agar polysaccharide complex and sulfation of agarose allowed us to identify the signal as highly sulfated saccharides found in agar or carrageenans. Purification of hydrolyzed κ-carrageenan ultimately led to the identification of the signal as a small fragment of a large linear polysaccharide, i.e., an oligosaccharide of five or more sugars with a repeating disaccharide motif containing d-galactose-4-sulfate (G4S) 1,4-linked to 3,6-anhydro-α-d-galactose (DA), G4S-(DA-G4S) n≥2IMPORTANCE Most environmental bacteria cannot initiate growth on agar plates, but they can flourish on the same plates once growth is initiated. While there are a number of names for and manifestations of this phenomenon, the underlying cause appears to be the requirement for a molecular signal indicating safe growing conditions. Micrococcus luteus has become a model organism for studying this growth initiation process, often called resuscitation, because of its apparent connection with the persistent or dormant form of Mycobacterium tuberculosis, an important human pathogen. In this report, we identify a highly sulfated saccharide from agar or carrageenans that robustly resuscitates dormant M. luteus on agarose plates. We identified and characterized the signal as a small repeating disaccharide motif. Our results indicate that signals inherent in or absent from the polysaccharide composition of solid growth media can have major effects on bacterial growth.

Changed immune and miRNA response in RAW264.7 cells infected with cell wall deficient mycobacterium tuberculosis.

Cell wall deficient (CWD) forms of Mycobacterium tuberculosis (Mtb) confers a marked resistance to immune system of the host. However, there is limit data on the effect of intracellular CWD-Mtb infection on macrophages. In the study, effects of CWD-Mtb on cell viability, cytokine response and miRNA expression of macrophages were analyzed. Cell viability was reduced, levels of interleukin-1α(IL-1α), IL-1β, IL-6, IL-10 and interferon-γ (IFN-γ) were also significantly changed after infection of RAW264.7 cells with CWD-Mtb. A total of 105miRNAs were deregulated between CWD-Mtb and wild Mtb group, and among them, miR-29b was upregulated in CWD-Mtb group. Downregulation of miR-29b resulted in significant elevation level of IFN-γ mRNA. Involved signaling pathways of potential target genes of differentially expressed miRNAs mainly focused on Tcell receptor signaling pathway, MAPK signaling pathway, neurotrophin signaling pathway, and regulation of actin cytoskeleton. Taken together, the results showed that cytokine production of CWD-Mtb infected macrophages was altered and many miRNAs were involved in regulation of macrophage response to CWD-Mtb infection, which probably determined the differential outcome following different phenotype Mtb infection. These findings open up a new and interesting avenue for an improved understanding of pathogenesis of CWD-Mtb.

Protocolo de diagnóstico y tratamiento de la artritis séptica sobre una articulación nativa

Septic arthritis is an inflammatory process due to infection that affects the synovial and articular cartilage destruction occurs. The most common etiology of acute septic arthritis is Staphylococcus aureus evolution and chronic forms of Mycobacterium tuberculosis and other atypical mycobacteria, particularly in immunocompromised patients. Leukocyte count, C-reactive protein, erithro-sedimentation rate and obtaining synovial fluid for biochemical study, a Gram stain and culture before starting antibiotic treatment are recommended. Treatment includes drainage of the joint cavity, immobilize the joint in the initial phase and an empirical antibiotic treatment should be based on the result of the Gram stain.

A nonhuman primate toxicology and immunogenicity study evaluating aerosol delivery of AERAS-402/Ad35 vaccine

Bacille Calmette-Guérin (BCG), the only licensed vaccine for the prevention of tuberculosis (TB), provides only limited protection against certain forms of Mycobacterium tuberculosis (Mtb) infection. While infection with Mtb can be treated with antibiotics, the therapy is expensive, toxic, and requires several months for treatment. In addition, the emergence of drug resistant strains limits the impact of antibiotics and underlines the importance of developing a more effective vaccine to control this disease. Given that pulmonary TB is the most common form of the disease, a vaccine capable of inducing lung-resident immunity may be advantageous for combating this infection. New advances in pulmonary delivery make this route of vaccination feasible and affordable. Here, we evaluate the safety and immunogenicity of an aerosolized Ad35-based vaccine, AERAS-402, delivered to the lungs in nonhuman primates as part of a GLP acute and chronic toxicology and safety study. In this study, animals received three high doses (1 x 1011 vp) of AERAS-402 by inhalation via a nebulizer at 1-week intervals. Aerosol delivery of AERAS-402 resulted in an increase in relative lung weights as well as microscopic findings in the lungs, mediastinal lymph nodes, bronchus-associated lymphatic tissue, and the naso-oropharynx that were consistent with the induction of an immune response during the acute phase. These findings resolved by the chronic phase and were considered to be non-adverse. Furthermore, we observed transient vaccine-specific immune responses in the peripheral blood as well as sustained high-level polyfunctional CD4+ and CD8+ T cell responses in the bronchoalveolar lavage fluid of vaccinated nonhuman primates. The data suggest that pulmonary delivery of Ad35-based vaccines can be safe and can induce potent lung-resident immunity.

A Case of Multidrug-Resistant Monoarticular Joint Tuberculosis in a Renal Transplant Recipient

Tuberculosis (TB) is a common opportunistic infection after renal transplantation. The risk of TB in renal transplant recipients is reported to be 20 to 74 times higher than in the general population. Although extrapulmonary TB occurs frequently, isolated ankle joint TB is a rare form of extrapulmonary TB infection. It is often difficult to diagnose because of its atypical presentation; management is complex, especially with multidrug-resistant TB, the need for a prolonged course of therapy, and the risks of drug interactions and drug toxicity. We report herein a case of a 60-year-old female renal allograft recipient who developed multidrug-resistant ankle joint TB 11 months after her deceased donor renal transplantation. She presented to the emergency department with escalating pain and swelling of the left ankle, difficulty in ambulation, and a low-grade fever. An x-ray of the ankle revealed an effusion and soft tissue swelling. A synovial fluid culture was performed which tested positive for acid fast bacilli which grew a multidrug-resistant form of Mycobacterium tuberculosis. She was initially treated with isoniazid, rifampin, ethambutol, and pyrazinamide; then therapy was tailored secondary to the resistant nature of the organism. She received a combination of extensive debridement of the joint and institution of second-line anti-TB therapy with pyrazinamide, ethambutol, moxifloxacin, and ethionamide. To our knowledge, no other cases of multidrug-resistant TB have been reported in the literature after renal transplantation. This case shows both an atypical presentation of TB and the difficulties in managing a transplant patient with this disease.

The PCR-Based Diagnosis of Central Nervous System Tuberculosis: Up to Date

Central nervous system (CNS) tuberculosis, particularly tuberculous meningitis (TBM), is the severest form of Mycobacterium tuberculosis (M.Tb) infection, causing death or severe neurological defects in more than half of those affected, in spite of recent advancements in available anti-tuberculosis treatment. The definitive diagnosis of CNS tuberculosis depends upon the detection of M.Tb bacilli in the cerebrospinal fluid (CSF). At present, the diagnosis of CNS tuberculosis remains a complex issue because the most widely used conventional “gold standard” based on bacteriological detection methods, such as direct smear and culture identification, cannot rapidly detect M.Tb in CSF specimens with sufficient sensitivity in the acute phase of TBM. Recently, instead of the conventional “gold standard”, the various molecular-based methods including nucleic acid amplification (NAA) assay technique, particularly polymerase chain reaction (PCR) assay, has emerged as a promising new method for the diagnosis of CNS tuberculosis because of its rapidity, sensitivity and specificity. In addition, the innovation of nested PCR assay technique is worthy of note given its contribution to improve the diagnosis of CNS tuberculosis. In this review, an overview of recent progress of the NAA methods, mainly highlighting the PCR assay technique, was presented.

CERVICAL MEDIASTINOSCOPY FOR PARATRACHEAL MASSES IN PEDIATRIC PATIENTS

A cytological diagnosis is essential for a definitive diagnosis in children who have paratracheal lesions. Thirteen pediatric patients were biopsied using cervical mediastinoscopy. Age, gender, preoperative diagnosis, and postoperative biopsy results and complications were reviewed. Five patients had mediastinal lesions residuing or recurring after chemotherapy for either Hodgkin disease or non-Hodgkin lymphoma. In 2 of these patients, the diagnosis was recurrent disease. Among the 8 patients presenting with a paratracheal mass or enlarged lymph nodes, histopathologic diagnosis showed tuberculosis in 3 children, Hodgkin disease in 2 children, and histiocytosis X and non-Hodgkin lymphoma 1 patient in each. This study shows that cervical mediastinoscopy gave 100% correct diagnosis for mediastinal residual malignancies or uncommon forms of mycobacterium tuberculosis with paratracheal masses.

Epidemiologic Classics of Carter, Maxcy, Trudeau, and Smith

Four great epidemiologists whose work so concisely linked clinical observations, epidemiologic clues, and logical preventive measures are discussed. Henry Rose Carter set the stage for the Walter Reed successes in Cuba by showing that 9-16 days must elapse after contact before yellow fever develops. This provided the link for the Reed group to allow the "virus" to incubate in the mosquito before becoming infectious. Kenneth Maxcy clarified the controversy between endemic typhus fever and Brill's disease in the southeastern United States. His clinical, epidemiologic, and laboratory findings led him to propose that the causative organism (Rickettsia typhi) was in rodents and the probable vector, fleas. When confirmed, effective control measures were applied. Two other American investigators, Edward L. Trudeau and Theobald Smith, helped prove Robert Koch wrong on three counts: (1) Tuberculin is not an effective therapeutic agent for tuberculosis; (2) there are two distinct types of tubercle bacillus, human and bovine; and (3) the bovine form of Mycobacterium tuberculosis is remarkably pathogenic for humans. The significance of these findings is unlimited.

Stabilization of various forms of mycobacterium tuberculosis

Rapidly growing, spore-bearing, not acid-fast rods, termed Form 2 mycobacteria, were obtained from a strain of Mycobacterium tuberculosis (Form 1) which has been aerated at intervals. Frequent and rapid previous subcultivation of the Form 1 strain prevented the isolation of Form 2 organisms. The development of the Form 2 strains as pseudo-branching filaments which fragmented to form multiplying cocci was also hindered by frequent subcultivation of the Form 2 strain. These results suggest that Form 1 and Form 2 strains can be stabilized under certain conditions of laboratory culture purely as acid-fast bacilli or as spore-forming rods, respectively. Furthermore, the experiments provide evidence that the Form 2 organisms did not arise from contaminants growing on Löwenstein-Jensen medium which had been conditioned by the simultaneous growth of the Form 1 strain.