Molecular identification of nontuberculous mycobacteria using the rpoB, argH and cya genes analysis

Mechanisms of Staphylococcus aureus Antibiotics Resistance Revealed by Adaptive Laboratory Evolution

Infection caused by drug-resistant Staphylococcus aureus is a serious public health and veterinary concern. Lack of a comprehensive understanding of the mechanisms underlying the emergence of drug-resistant strains, it makes S. aureus one of the most intractable pathogenic bacteria. To identify mutations that confer resistance to anti-S. aureus drugs, we established a laboratory-based adaptive evolution system and performed 10 rounds of evolution experiments against 15 clinically used antibiotics. We discovered a panel of known and novel resistance-associated sites after performing whole-genome sequencing. Furthermore, we found that the resistance evolved at distinct rates. For example, streptomycin, rifampicin, fusidic acid and novobiocin all developed significant resistance quickly in the second round of evolution. Intriguingly, the cross-resistance experiment reveals that nearly all drug-resistant strains have varying degrees of increased sensitivity to fusidic acid, pointing to a novel approach to battle AMR. In addition, the in silico docking analysis shows that the evolved mutants affect the interaction of rifampcin-rpoB, as well as the novobiocin-gyrB. Moreover, for the genes we got in the laboratory evolution, mutant genes of clinical isolates of human had significant differences from the environmental isolates and animal isolates. We believe that the strategy and data set in this research will be helpful for battling AMR issue of S. aureus, and adaptable to other pathogenic microbes.

Dual spatial host-bacterial gene expression in Mycobacterium abscessus respiratory infections

Co-localization of spatial transcriptome information of host and pathogen can revolutionize our understanding of microbial pathogenesis. Here, we aimed to demonstrate that customized bacterial probes can be successfully used to identify host-pathogen interactions in formalin-fixed-paraffin-embedded (FFPE) tissues by probe-based spatial transcriptomics technology. We analyzed the spatial gene expression of bacterial transcripts with the host transcriptomic profile in murine lung tissue chronically infected with Mycobacterium abscessus embedded in agar beads. Customized mycobacterial probes were designed for the constitutively expressed rpoB gene (an RNA polymerase β subunit) and the virulence factor precursor lsr2, modulated by oxidative stress. We found a correlation between the rpoB expression, bacterial abundance in the airways, and an increased expression of lsr2 virulence factor in lung tissue with high oxidative stress. Overall, we demonstrate the potential of dual bacterial and host gene expression assay in FFPE tissues, paving the way for the simultaneous detection of host and bacterial transcriptomes in pathological tissues.

Epidemiology and laboratory detection of non-tuberculous mycobacteria

The global incidence of non-tuberculous mycobacteria (NTM) infections is on the rise. This study systematically searched several databases, including PubMed, Web of Science, Google Scholar, and two Chinese libraries (Chinese National Knowledge Infrastructure and Wanfang) to identify relevant published between 2013 and 2023 related to the isolation of NTM in clinical specimens from various countries and provinces of China. Furthermore, a comprehensive literature review was conducted in PubMed and Google Scholar to identify randomized clinical trials, meta-analyses, systematic reviews, and observational studies that evaluated the diagnostic accuracy and impact of laboratory detection methods on clinical outcomes. This review presented the most recent epidemiological data and species distributions of NTM isolates in several countries and provinces of China. Moreover, it provided insights into laboratory bacteriological detection, including the identified strains, advantages and disadvantages, recent advancements, and the commercial Mycobacterium identification kits available for clinical use. This review aimed to aid healthcare workers in understanding this aspect, enhance the standards of clinical diagnosis and treatment, and enlighten them on the existing gaps and future research priorities.

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.

Trends in the Antibiotic Resistance of Non-Tuberculous Mycobacteria in Iran: A Systematic Review and Meta-Analysis

Background

Non-tuberculous mycobacteria (NTM) infections have been continuously increasing as major concerns of public health in Iran. Because innate resistance of NTM species, the treatment of these infections is difficult task, but until now resistance pattern of NTM and suitable regimens are not determined.

Methods

We systematically searched the relevant studies in PubMed, Scopus, and Embase (Until Dec 2022). All statistical analyses were carried out using the statistical package R.

Results

Eleven studies included in the analysis were performed in 6 provinces and investigated 1223 NTM clinical species. The majority of the studies originated in Tehran. Among the first-line anti-TB drugs, almost all NTM species were highly resistant to first-line anti-TB drugs. No significant difference in the isoniazid resistance rate was found in the slow or rapid-growing species and Runyon's classification of NTM isolates. A decreased in the prevalence of ciprofloxacin, clarithromycin, and moxifloxacin resistance were showed in during 2013-2022 years.

Conclusion

Most investigated antibiotics have a minor effect on NTM species and a steady increase of resistance has been seen in last few years then, need more-effective alternative regimens is clear.