Metabolic profiles of multidrug resistant and extensively drug resistant Mycobacterium tuberculosis unveiled by metabolomics.

Although treatable with antibiotics, tuberculosis is a leading cause of death. Mycobacterium tuberculosis antibiotic resistance is becoming increasingly common and disease control is challenging. Conventional drug susceptibility testing takes weeks to produce results, and treatment is often initiated empirically. Therefore, new methods to determine drug susceptibility profiles are urgent. Here, we used mass-spectrometry-based metabolomics to characterize the metabolic landscape of drug-susceptible (DS), multidrug-resistant (MDR) and extensively drug-resistant (XDR) M. tuberculosis. Direct infusion mass spectrometry data showed that DS, MDR, and XDR strains have distinct metabolic profiles, which can be used to predict drug susceptibility and resistance. This was later confirmed by Ultra-High-Performance Liquid Chromatography and High-Resolution Mass Spectrometry, where we found that levels of ions presumptively identified as isoleucine, proline, hercynine, betaine, and pantothenic acid varied significantly between strains with different drug susceptibility profiles. We then confirmed the identification of proline and isoleucine and determined their absolute concentrations in bacterial extracts, and found significantly higher levels of these amino acids in DS strains, as compared to drug-resistant strains (combined MDR and XDR strains). Our results advance the current understanding of the effect of drug resistance on bacterial metabolism and open avenues for the detection of drug resistance biomarkers.

Immunogenicity of a recombinant Mycobacterium smegmatis vaccine expressing the fusion protein CMX in cattle from Goiás State, Brazil.

This study aimed to evaluate the immunogenicity of a recombinant Mycobacterium smegmatis vaccine expressing the CMX fusion protein composed of immunodominant epitopes Ag85C, MPT51 and HspX of Mycobacterium tuberculosis, which are important mycobacteria virulence factors. A group of Nelore heifers that were 10 to 12 months of age and negative for the tuberculin skin test (TST) were immunized with four doses of the recombinant vaccine mc(2)-CMX (M. smegmatis-Ag85C-MPT51-HspX) during a period of one year. Before each immunization, blood was collected to obtain sera for antibody analysis. Serological analysis demonstrated that mc(2)-CMX was able to induce a humoral response with increased levels of specific IgG antibodies against CMX, despite minimum antibody levels being detected for individual Ag85C, MPT51 or HspX recombinant antigens. However, there was no significant increase in specific CD4(+) IFN-γ-positive T cells. Lymphadenomegaly was observed in superficial cervical lymph nodes adjacent to the site of vaccination among mc(2)-CMX-vaccinated bovines, and the histopathological analysis demonstrated follicular hyperplasia without inflammatory infiltrate or granuloma formation. Animals remained negative for the TST until the end of the experiments, showing no cross-reactivity with the recombinant vaccine and tuberculin proteins. We discuss the potential of mc(2)-CMX to induce an immune response in cattle.