ABSTRACT
Objective/Background: Mycobacterium tuberculosis [MTB] causes active tuberculosis [TB] in only a small percentage of infected people. In most cases, the infection is clinically latent, where bacilli can persist in human hosts for years without causing disease. Surprisingly, the biology of such persister cells is largely unknown. This study describes the isolation, identification, and whole-genome sequencing [WGS] of latent TB bacilli after 782 days [26 months] of latency [the ability of MTB bacilli to lie persistent]
Methods: The in vitro double-stress model of latency [oxygen and nutrition] was designed for MTB culture. After 26 months of latency, MTB cells that persisted were isolated and investigated under light and atomic force microscopy. Spoligotyping and WGS were performed to verify the identity of the strain
Results: We established a culture medium in which MTB bacilli arrest their growth, reduce their size [0.3-01 microm], lose their acid fastness [85-90%] and change their shape. Spoligopatterns of latent cells were identical to original H[37]R[v], with differences observed at spacers two and 14. WGS revealed only a few genetic changes relative to the already published H[37]R[v] reference genome. Among these was a large 2064-hp insertion [RvD6], which was originally detected in both H[37]R[a] and CDC1551, but not H[37]R[v]
Subject(s)
In Vitro Techniques , Population , Cell Wall , Genotyping Techniques , Genome-Wide Association StudyABSTRACT
This study was performed in the city of Minsk in Belarus, where a very severe problem with MDR-TB was demonstrated in a recent drug resistant survey. The aim of this study was to use molecular typing of MDR and pan-susceptible clinical isolates of Mycobacterium tuberculosis to increase the understanding of the transmission patterns and possible differences between the strains causing susceptible and drug-resistant tuberculosis. Study population and methods Consecutive isolates from pulmonary TB patients in Minsk were collected at the Belarusian National Reference Laboratory. Isolates found to be either pan-susceptible or MDR were included in the study, which totally comprised 81 MDR and 82 pan-susceptible clinical isolates. All isolates were characterized by spoligotyping. The major clusters were characterized using sequencing of the pncA gene. Three out of four MDR cases were caused by one out of two drug-resistant clones of M. tuberculosis belonging to the Beijing and T1 genotypes, respectively. A single T1 clone, SIT No. 266, found exclusively in the MDR cohort, was shown to cause no less than 30% of all MDR-TB cases. Discussion: The findings indicate that the major cause of MDR-TB in Minsk is an ongoing transmission of certain already resistant M. tuberculosis strains. The significant transmission of MDR-TB in Minsk underlines the urgent need for strengthened infection control measures to limit the transmission in order to better control MDR-TB