Latent tuberculosis: interaction of virulence factors in Mycobacterium tuberculosis

Molecular Biology Reports - Tuberculosis (TB) remains a prominent health concern worldwide. Besides extensive research and vaccinations available, attempts to control the pandemic are cumbersome...     

Congenital tuberculosis associated with maternal disseminated miliary tuberculosis

Untreated tuberculosis during pregnancy presents a serious risk for transmission of disease to the newborn and can result in adverse perinatal and obstetrical outcomes. Tuberculosis during pregnancy and congenital tuberculosis are infrequent conditions and are difficult to diagnose due the non-specificity of the symptoms. A case report is presented of a woman who had no children previously with disseminated miliary tuberculosis. Tuberculosis symptoms appeared immediately after birth of the first child, with a clinical diagnosis on the second month after childbirth, whereupon the patient died. The son, a premature infant, showed disease symptoms from the first day, with primary pulmonary complex and persistent atelectasis due to bronchial obstruction. The obstruction was due to thoracic lymphadenitis and coinfection with cytomegalovirus. The infant received standard treatment and his condition improved.     

Electrochemical-based biosensors for detection of Mycobacterium tuberculosis and tuberculosis biomarkers

Abstract

Early detection of tuberculosis (TB) reduces the interval between infection and the beginning of treatment. However, commercially available tests cannot discriminate between BCG-vaccinated healthy persons and patients. Also, they are not suitable to be used for immunocompromised persons. In recent years, biosensors have attracted great attention due to their simple utility, accessibility, and real-time outputs. These sensors are increasingly being considered as pioneering tools for point-of-care diagnostics in communities with a high burden of TB and limited accessibility to reference laboratories. Among other types of biosensors, the electrochemical sensors have the advantages of low-cost operation, fast processing, simultaneous multi-analyte analyzing, operating with turbid samples, comparable sensitivity and readily available miniaturization. Electrochemical biosensors are sub-divided into several categories including: amperometric, impedimetric, potentiometric, and conductometric biosensors. The biorecognition element in electrochemical biosensors is usually based on antibodies (immunosensors), DNAs or PNAs (genosensors), and aptamers (aptasensors). In either case, whether an interaction of the antigen–antibody/aptamer or the hybridization of probe with target mycobacterial DNA is detected, a change in the electrical current occurs that is recorded and displayed as a plot. Therefore, impedimetric-based methods evaluate resistance to electron transfer toward an electrode by a Nyquist plot and amperometric/voltammetric-based methods weigh the electrical current by means of cyclic voltammetry, square wave voltammetry, and differential pulse voltammetry. Electrochemical biosensors provide a promising scope for the new era of diagnostics. As a consequence, they can improve detection of Mycobacterium tuberculosis traces even in attomolar scales.     

The MODS method for diagnosis of tuberculosis and multidrug resistant tuberculosis

Patients with active pulmonary tuberculosis (TB) infect 10-15 other persons per year, making diagnosing active TB essential to both curing the patient and preventing new infections. Furthermore, the emergence of multidrug resistant tuberculosis (MDRTB) means that detection of drug resistance is necessary for stopping the spread of drug-resistant strains. The microscopic-observation drug-susceptibility (MODS) assay is a low-cost, low-tech tool for high-performance detection of TB and MDRTB. The MODS assay is based on three principles: 1) mycobacterium tuberculosis (MTB) grows faster in liquid media than on solid media 2) microscopic MTB growth can be detected earlier in liquid media than waiting for the macroscopic appearance of colonies on solid media, and that growth is characteristic of MTB, allowing it to be distinguished from atypical mycobacteria or fungal or bacterial contamination 3) the drugs isoniazid and rifampicin can be incorporated into the MODS assay to allow for simultaneous direct detection of MDRTB, obviating the need for subculture to perform an indirect drug susceptibility test. Competing current diagnostics are hampered by low sensitivity with sputum smear, long delays until diagnosis with solid media culture, prohibitively high cost with existing liquid media culture methods, and the need to do subculture for indirect drug susceptibility testing to detect MDRTB. In contrast, the non-proprietary MODS method has a high sensitivity for TB and MDRTB, is a relatively rapid culture method, provides simultaneous drug susceptibility testing for MDRTB, and is accessible to resource-limited settings at just under $3 for testing for TB and MDRTB.Download video file.^{(243M, mp4)}     

Live attenuated mutants of Mycobacterium tuberculosis as candidate vaccines against tuberculosis

The recent advances in genetic tools to manipulate Mycobacterium tuberculosis have led to the construction of defined mutants and to the study of their role in the virulence and pathogenesis of tuberculosis. The safety and vaccine potential of a few of these M. tuberculosis mutants as candidate vaccines against tuberculosis are discussed.