Search

Mycobacterium smegmatis strain MC2 155 is an attractive model organism for the study of M. tuberculosis and other mycobacterial pathogens, as it can grow well using cholesterol as a carbon resource. However, its global transcriptomic response remains largely unrevealed. In this study, M. smegmatis MC2 155 cultivated in androstenedione, cholesterol and glycerol supplemented media were collected separately for a RNA-Sequencing study. The results showed that 6004, 6681 and 6348 genes were expressed in androstenedione, cholesterol and glycerol supplemented media, and 5891 genes were expressed in all three conditions, with 237 specially expressed in cholesterol added medium. A total of 1852 and 454 genes were significantly up-regulated by cholesterol compared with the other two supplements. Only occasional changes were observed in basic carbon and nitrogen metabolism, while almost all of the genes involved in cholesterol catabolism and mammalian cell entry (MCE) were up-regulated by cholesterol, but not by androstenedione. Eleven and 16 gene clusters were induced by cholesterol when compared with glycerol or androstenedione, respectively. This study provides a comprehensive analysis of the cholesterol responsive transcriptome of M. smegmatis. Our results indicated that cholesterol induced many more genes and increased the expression of the majority of genes involved in cholesterol degradation and MCE in M. smegmatis, while androstenedione did not have the same effect. [ABSTRACT FROM AUTHOR]

An important prerequisite for the effective control, timely diagnosis, and successful treatment of mycobacterial infections in both humans and animals is a rapid, specific, and sensitive detection technique. Culture is still considered the gold standard in the detection of viable mycobacteria; however, mycobacteria are extremely fastidious and slow-growing microorganisms, and therefore cultivation requires a very long incubation period to obtain results. Polymerase Chain Reaction (PCR) methods are also frequently used in the diagnosis of mycobacterial infections, providing faster and more accurate results, but are unable to distinguish between a viable and non-viable microorganism, which results in an inability to determine the success of tuberculosis patient treatment or to differentiate between an active and passive infection of animals. One suitable technique that overcomes these shortcomings mentioned is the phage amplification assay (PA). PA specifically detects viable mycobacteria present in a sample within 48 h using a lytic bacteriophage isolated from the environment. Nowadays, an alternative approach to PA, a commercial kit called Actiphage™, is also employed, providing the result within 6–8 h. In this approach, the bacteriophage is used to lyse mycobacterial cells present in the sample, and the released DNA is subsequently detected by PCR. The objective of this review is to summarize information based on the PA used for detection of mycobacteria significant in both human and veterinary medicine from various kinds of matrices. [ABSTRACT FROM AUTHOR]

Roughly a third of the world's population is estimated to have latent Mycobacterium tuberculosis infection, being at risk of developing active tuberculosis (TB) during their lifetime. Given the inefficacy of prophylactic measures and the increase of drug-resistant M. tuberculosis strains, there is a clear and urgent need for the development of new and more efficient chemotherapeutic agents, with selective toxicity, to be implemented on patient treatment. The component enzymes of the shikimate pathway, which is essential in mycobacteria and absent in humans, stand as attractive and potential targets for the development of new drugs to treat TB. This review gives an update on published work on the enzymes of the shikimate pathway and some insight on what can be potentially explored towards selective drug development. [ABSTRACT FROM AUTHOR]