Tuberculosis (TB) is currently the number one killer among infectious diseases worldwide. Lipids are abundant molecules during the infectious cycle of Mycobacterium tuberculosis (Mtb) and studies better mimicking its actual metabolic state during pathogenesis are needed. Though most studies have focused on the mycobacterial lipid metabolism under standard culture conditions, little is known about the transcriptome of Mtb in a lipid environment. Here we determined the transcriptome of Mtb H37Rv in a lipid-rich environment (cholesterol and fatty acid) under aerobic and hypoxic conditions, using RNAseq. Lipids significantly induced the expression of 368 genes. A main core lipid response was observed involving efflux systems, iron caption and sulfur reduction. In co-expression with ncRNAs and other genes discussed below, may act coordinately to prepare the machinery conferring drug tolerance and increasing a persistent population. Our findings could be useful to tag relevant pathways for the development of new drugs, vaccines and new strategies to control TB.

Bedaquiline (BDQ) has been proven to be effective in the treatment of multidrug-resistant tuberculosis. We hypothesized that BDQ could be a potential agent to treat nontuberculous mycobacterial (NTM) infection. The objective of this study was to evaluate the in vitro activity of BDQ against rapidly growing mycobacteria by assessing the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against 18 NTM strains. For MIC determination we performed the resazurin microtitre assay broth dilution, and for the MBC the c.f.u. was determined. BDQ exhibited a strong inhibitory effect against most NTM tested; however, for some NTM strains the MBC was significantly higher than the MIC. A new finding is that Mycobacterium flavescens has a mutation in the gene atpE associated with natural resistance to BDQ. These preliminary promising results demonstrate that BDQ could be potentially useful for the treatment of NTM.

Background: Nontuberculous mycobacteria (NTM) are environmental opportunistic pathogens found in natural and human-engineered waters, including drinking water distribution systems and household plumbing. This pilot study examined the frequency of occurrence of NTM in household potable water samples in Mexico City. Potable water samples were collected from the “main house faucet” and kitchen faucet. The presence of aerobic-mesophilic bacteria (AMB), total coliforms (TC), fecal coliforms (FC) and NTM species were determined. Mycobacteria species were identified by PCR restriction enzyme pattern analysis (PRA) of the 65-kDa heat shock protein gene (hsp65) and sequencing of the hypervariable region 2 (V2) of the 16S rRNA gene and of the rpo B gene. Results: AMB (100 CFU/ml). TC and FC were detected in four and one samples, respectively. NTM species were recovered from 16% samples (19/120) and included M. mucogenicum (nine), M. porcinum (three), M. avium (three), M. gordonae (one), M. cosmeticum (one), M. fortuitum (one), and Mycobacterium sp (one). All household water samples that contained NTM complied with the standards required to grade the water as “good quality” potable water. Conclusion: Household potable water may be a potential source of NTM infection in Mexico City.

Adolescent pregnancy is a significant public health concern, with maternal and fetal risks compounded by pregnancy-related anatomical, hormonal, and urinary changes that predispose to urinary tract infections (UTIs). Alterations in the urinary microbiome may further influence infection susceptibility, yet little is known about its role during adolescent pregnancy. This study analyzed the urinary microbiome of adolescent pregnant patients and its association with UTI and recurrent UTI (rUTI) across gestation. Healthy adolescents were enrolled in the first trimester and followed through subsequent trimesters, with urine samples collected at each visit for microbiological diagnosis. Patients were classified as healthy (34 samples), single UTI (22 samples), or rUTI (31 samples), and oxford-nanopore 16S rRNA sequencing was used to assess taxonomic composition, microbial diversity, and operational taxonomic units. Distinct trimester-specific patterns were observed, with Lactobacillus iners progressively increasing and L. kitasatonis emerging as a dominant taxon during adolescent pregnancy. Interestingly, rUTI cases showed persistent E. coli, reduced L. kitasatonis and L. ultunensis in the second trimester, and the appearance of Fannyhessea vaginae (Atopobium vaginae) in the third. These findings suggest a potential microbial signature of rUTI in adolescent pregnancy, underscoring the need for personalized preventive strategies and the establishment of microbiome-based clinical cutoffs.

The general features of the shift to a dormant state in mycobacterial species include several phenotypic changes, reduced metabolic activities, and increased resistance to host and environmental stress conditions. In this study, we aimed to provide novel insights into the viability state and morphological changes in dormant M. smegmatis that contribute to its long-term survival under starvation or hypoxia. To this end, we conducted assays to evaluate cell viability, morphological changes and gene expression. During starvation, M. smegmatis exhibited a reduction in cell length, the presence of viable but non-culturable (VBNC) cells and the formation of anucleated small cells, potentially due to a phenomenon known as reductive cell division. Under hypoxia, a novel population of pleomorphic mycobacteria with a rough surface before the cells reached nonreplicating persistence 1 (NRP1) was identified. This population exhibited VBNC-like behaviour, with a loss of cell wall rigidity and the presence of lipid-body-like structures. Based on dosR and hspX expression, we suggest that M. smegmatis encounters reductive stress conditions during starvation, while lipid storage may induce oxidative stress during hypoxia. These insights into the heterogeneous populations presented here could offer valuable opportunities for developing new therapeutic strategies to control dormant mycobacterial populations.

The first-in-class diarylquinoline (DARQ) bedaquiline (BDQ) is in the medicines list for drug-resistant tuberculosis. TBAJ-587 is a next-generation DARQ with improved anti-Mycobacterium tuberculosis (Mtb) activity and reduced cardiac repolarization abnormalities. Methods. The in-vitro efficacy of TBAJ-587 and its main metabolites (M2, M3 and M12) was analyzed under standard (ST) growth conditions, with cholesterol (CHO), or fatty acids (FA) as alternative carbon sources. Minimal inhibitory concentration (MIC) assays and time-kill assays (TKA) linked to drug measurements in bacterial samples were performed to allow correlation of pharmacodynamics (PD) with actual pharmacokinetics (PK). The most active compounds, TBAJ-587 and its M3 metabolite, exhibited broth media and concentration dependent efficacy showing a bactericidal effect at ≥5x MIC. Bacterial cultures treated with 1x MIC and 2x MIC of TBAJ-587 resumed growth after 28 days and displayed moderate increased MIC values compared to untreated conditions, which were linked to new variants of BDQ resistance mutations in the atpE, atpB, and Rv0678 genes. This study revealed TBAJ-587 and metabolites bind to polystyrene plastic-ware, the most commonly used material in antimicrobial research, being the effective unbound drug concentration dependent on the media composition. PKPD analyses determined that Mtb was killed with lower exposures of TBAJ-587 and M3 than expected in ST and FA broth, suggesting previously underestimated potency in these media. This is the first in-vitro study to precisely link compound activities (PD) to their effective concentration (PK) over time in Mtb cultures, providing improved longitudinal data to feed models for translational research.