Objective: To assess the molecular mechanism of rifampin (RMP) resistance in clinical strains of Mycobacterium tuberculosis.
Design: The molecular nature of a part of the rpoB gene in 77 M. tuberculosis clinical strains isolated in Korea was analyzed using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and PCR-sequence analysis.
Results: Among 67 RMP-resistant isolates, 50 showed SSCP profiles different from that of an RMP-sensitive control strain, M. tuberculosis H37Rv, indicating the possible existence of a sequence alteration in this region of the rpoB gene, while 17 resistant isolates displayed SSCP profiles indistinguishable from that of the sensitive control strain. Subsequently, 17 clinical isolates whose SSCP profiles were difficult to distinguish from the control strain were subjected to sequence analysis. The analysis revealed that all 17 isolates did indeed contain mutations in the 81 bp region of the rpoB gene, which is associated with RMP resistance.
Conclusion: The results from our study clearly indicate that the molecular mechanism of RMP resistance in M. tuberculosis isolates from Korea involves alterations in the rpoB gene. In addition, this study suggests that PCR-direct sequence analysis works more efficiently and accurately than PCR-SSCP analysis for rapid screening of RMP-resistant M. tuberculosis clinical isolates.
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Med Microbiol Immunol
January 2025
Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal.
\nKlebsiella pneumoniae is a common pathogen of healthcare-associated infections expressing a plethora of antimicrobial resistance loci, including ADP-ribosyltransferase coding genes (arr), able to mediate rifampicin resistance. The latter has activity against a broad range of microorganisms by inhibiting DNA-dependent RNA polymerases. This study aims to characterise the arr distribution and genetic context in 138 clinical isolates of K.
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International Reference Laboratory of Mycobacteriology, Statens Serum Institut, Copenhagen, Denmark.
Four novel nontuberculous mycobacteria were discovered from a historical strain collection at the International Reference Laboratory of Mycobacteriology at Statens Serum Institut in Copenhagen, Denmark. Phylogenetic analysis combining the 16S , internal transcribed spacer and 23S elements, as well as a single-copy core-gene (, , and ) analysis of these freeze-dried mycobacteria, clinically isolated from gastric lavage samples between 1948 and 1955, showed to be associated with type strains grouping within the Terra and Fortuitum-Vaccae clade. Phenotypic characteristics, biochemical properties and fatty acid and mycolic acid profiles supported the classification as novel strains.
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Shanghai Key Laboratory of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China.
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.
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January 2025
Department of Respiratory Medicine, University of Occupational and Environmental Health, Japan, Japan.
A 69-year-old man with systemic sclerosis and interstitial pneumonia presented with an abnormal shadow in the right upper lung lobe. A thoracoscopic needle biopsy was performed on the right upper lobe lesion, and Mycobacterium malmoense was identified by 16S rRNA and rpoB gene sequencing. Surgical treatment was performed to obtain a radical cure, and lung squamous cell carcinoma and M.
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