RESUMEN
A breakthrough in molecular biology for the twenty-first century is CRISPR/Cas gene editing, which has been used in a variety of fields due to its simplicity, adaptability, and targeting. Given the current global challenge of severe bacterial resistance, difficulties in detecting antimicrobial resistance, and slow development of antimicrobial drugs, CRISPR/Cas gene-editing technology offers a promising avenue for the development of antibacterial treatments. On the one hand, CRISPR/Cas gene editing technology helps advance the study of bacterial functions and serves as a toolbox. For instance, Cas proteins and exogenous repair systems enable efficient and precise gene editing, nCas proteins and deaminase systems facilitate template-free and single base precision editing, dCas proteins and reverse transcriptase allow for repair-free gene editing, and dCas proteins and modified sgRNA enable gene expression level regulation and gene function analysis. On the other hand, its specific gene recognition and targeted DNA cleavage characteristics can be used for pathogen detection, elimination of drug-resistant bacteria and genes, and hold promise as a new strategy for clinical diagnosis and treatment.
RESUMEN
Polymyxin B and polymyxin E (colistin) are presently considered the last line of defense against human infections caused by multidrug-resistant Gram-negative organisms such as carbapenemase-producer Enterobacterales, Acinetobacter baumannii, and Klebsiella pneumoniae. Yet resistance to this last-line drugs is a major public health threat and is rapidly increasing. Polymyxin S2 (S2) is a polymyxin B analogue previously synthesized in our institute with obviously high antibacterial activity and lower toxicity than polymyxin B and colistin. To predict the possible resistant mechanism of S2 for wide clinical application, we experimentally induced bacterial resistant mutants and studied the preliminary resistance mechanisms. Mut-S, a resistant mutant of K. pneumoniae ATCC BAA-2146 (Kpn2146) induced by S2, was analyzed by whole genome sequencing, transcriptomics, mass spectrometry and complementation experiment. Surprisingly, large-scale genomic inversion (LSGI) of approximately 1.1 Mbp in the chromosome caused by IS26 mediated intramolecular transposition was found in Mut-S, which led to mgrB truncation, lipid A modification and hence S2 resistance. The resistance can be complemented by plasmid carrying intact mgrB. The same mechanism was also found in polymyxin B and colistin induced drug-resistant mutants of Kpn2146 (Mut-B and Mut-E, respectively). This is the first report of polymyxin resistance caused by IS26 intramolecular transposition mediated mgrB truncation in chromosome in K. pneumoniae. The findings broaden our scope of knowledge for polymyxin resistance and enriched our understanding of how bacteria can manage to survive in the presence of antibiotics.
RESUMEN
UHPLC-QTOF-MS was applied to non-targeted metabolomics study of mice infected with K. pneumoniae ATCC® BAA 2146 to discover potential biomarkers and metabolic pathways that are associated with sepsis. Fifty-eight metabolites were identified by principal components analysis (PCA) and partial least-squares discriminant analysis (OPLS-DA), which was combined with variable projection importance (VIP) and nonparametric test. Eighteen of the 58 metabolites were further found to be involved in 8 metabolic pathways, including nicotinate and nicotinamide metabolism, pyrimidine metabolism, vitamin B6 metabolism, taurine and hypotaurine metabolism, arginine and proline metabolism, alanine, aspartate and glutamate metabolism, D-glutamine and D-glutamate metabolism and glycerophospholipid metabolism.
RESUMEN
Objective: To establish the quality standards for Lingyangqingfei capsules. Methods: Microscopic identification of products, TLC identifications of Fructus Gardeniae and Cortex Moutan were carried out.Baicalin was determined by HPLC. Results: Baicalin in Lingyangqingfei capsules was about 1.5mg/capsule. The average recovery was 99.82% and RSD was 0.96%. Conclusion: The result is accurate and the reproducibility is good. This method can be used as the quality control of this preparation.