Genotypic analysis of nontuberculous mycobacteria isolated from raw milk and human cases in Wisconsin

A young woman with Mycobacterium chelonae complex infection caused by facial stem cell injection

In outpatient settings, Mycobacterium chelonae complex infection brought on by cosmetic injections are rather uncommon. We came across a case of infection brought on by a commercial stem cell injection.

Isolation and identification of nontuberculous mycobacteria from raw milk and traditional cheese based on the 16S rRNA and hsp65 genes, Tehran, Iran

As an important source of human food, milk can be a carrier of human pathogenic bacteria, including tuberculous and nontuberculous mycobacteria (NTM), in its raw and unpasteurized state. In this research, 175 raw milk samples and 175 traditional cheese samples were collected from traditional dairy stores in 22 regions of Tehran in a 9- month period from August 2019 to May 2020. Samples were prepared and transferred to a specialized laboratory, where they were inoculated in Lowenstein-Jensen (LJ) medium containing glycerol or sodium pyruvate, as well as Herrold's egg-yolk with and without Mycobactin J. to determine the sample's identity of samples. The recommended 16S rRNA (1436 bp) and hsp65 (644 bp) gene fragments from the positive isolates identified in Ziehl-Neelsen (Z-N) staining were amplified and sequenced using PCR and compared with the sequences of the gene fragments of reference strains available in the global GenBank database. No mycobacterial species were isolated from traditional cheese samples in microbial culture. In case of raw milk samples, a total of four bacteria were collected, all of which were found in the genetic differential testing to be NTM, including n = 1 Mycobacterium heraklionense, n = 2 Mycolicibacterium fortuitum, and n = 1 Mycobacterium thermoresistibile. The analysis of the results obtained by isolate sequencing using the 16S rRNA gene showed higher discriminatory power and percentage similarities in the identification of the isolates than the hsp65 gene.

Protective RNA nanovaccines against Mycobacterium avium subspecies hominissuis

The induction of an effective immune response is critical for the success of mRNA-based therapeutics. Here, we developed a nanoadjuvant system compromised of Quil-A and DOTAP (dioleoyl 3 trimethylammonium propane), hence named QTAP, for the efficient delivery of mRNA vaccine constructs into cells. Electron microscopy indicated that the complexation of mRNA with QTAP forms nanoparticles with an average size of 75 nm and which have ~90% encapsulation efficiency. The incorporation of pseudouridine-modified mRNA resulted in higher transfection efficiency and protein translation with low cytotoxicity than unmodified mRNA. When QTAP-mRNA or QTAP alone transfected macrophages, pro-inflammatory pathways (e.g., NLRP3, NF-kb, and MyD88) were upregulated, an indication of macrophage activation. In C57Bl/6 mice, QTAP nanovaccines encoding Ag85B and Hsp70 transcripts (QTAP-85B+H70) were able to elicit robust IgG antibody and IFN- ɣ, TNF-α, IL-2, and IL-17 cytokines responses. Following aerosol challenge with a clinical isolate of M. avium ss. hominissuis (M.ah), a significant reduction of mycobacterial counts was observed in lungs and spleens of only immunized animals at both 4- and 8-weeks post-challenge. As expected, reduced levels of M. ah were associated with diminished histological lesions and robust cell-mediated immunity. Interestingly, polyfunctional T-cells expressing IFN- ɣ, IL-2, and TNF- α were detected at 8 but not 4 weeks post-challenge. Overall, our analysis indicated that QTAP is a highly efficient transfection agent and could improve the immunogenicity of mRNA vaccines against pulmonary M. ah, an infection of significant public health importance, especially to the elderly and to those who are immune compromised.

Evidence, Challenges, and Knowledge Gaps Regarding Latent Tuberculosis in Animals

Mycobacterium bovis and other Mycobacterium tuberculosis complex (MTBC) pathogens that cause domestic animal and wildlife tuberculosis have received considerably less attention than M. tuberculosis, the primary cause of human tuberculosis (TB). Human TB studies have shown that different stages of infection can exist, driven by host–pathogen interactions. This results in the emergence of heterogeneous subpopulations of mycobacteria in different phenotypic states, which range from actively replicating (AR) cells to viable but slowly or non-replicating (VBNR), viable but non-culturable (VBNC), and dormant mycobacteria. The VBNR, VBNC, and dormant subpopulations are believed to underlie latent tuberculosis (LTB) in humans; however, it is unclear if a similar phenomenon could be happening in animals. This review discusses the evidence, challenges, and knowledge gaps regarding LTB in animals, and possible host–pathogen differences in the MTBC strains M. tuberculosis and M. bovis during infection. We further consider models that might be adapted from human TB research to investigate how the different phenotypic states of bacteria could influence TB stages in animals. In addition, we explore potential host biomarkers and mycobacterial changes in the DosR regulon, transcriptional sigma factors, and resuscitation-promoting factors that may influence the development of LTB.