Supandy Adeline, Mills Emma G, Fam Kyong T, Shields Ryan K, Hang Howard C, Van Tyne Daria
Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
Department of Immunology and Microbiology, Scripps Research, La Jolla, United States.
bioRxiv. 2025 Aug 4:2025.07.25.666922. doi: 10.1101/2025.07.25.666922.
is a member of the human gut microbiota that has evolved into a problematic nosocomial pathogen and leading cause of infections in hospitalized patients. Treatment of infections is complicated by antibiotic resistance, making it important to understand resistance mechanisms and their broader consequences in this pathogen. Here we explored the collateral effects of rifampin resistance-associated mutations in the RNA polymerase β-subunit (RpoB). Of 14,384 publicly available genomes, nearly one-third carried a mutation in the rifampin resistance-determining region (RRDR) of RpoB. In a local population of 710 clinical isolates collected from patients at a single hospital, we found significant associations between the presence of RRDR mutations and prior exposure to rifamycin antibiotics, as well as associations between RRDR mutations and altered daptomycin susceptibility. To investigate the phenotypic impacts of RRDR mutations, we generated and studied four isogenic strains with distinct RRDR mutations (Q473K, G482D, H486Y, S491L) that overlapped with clinical isolate variants. Transcriptomic and phenotypic analyses revealed allele-specific effects on gene expression, growth dynamics, antibiotic susceptibility, isopropanol tolerance, and cell wall physiology. One frequently observed mutation, H486Y, caused minimal transcriptional changes and enhanced bacterial fitness under antibiotic stress. In contrast, the S491L mutation induced extensive transcriptional changes and slowed bacterial growth, but also conferred increased isopropanol tolerance, potentially enhancing bacterial survival in the hospital. Overall, our findings highlight the multifaceted impacts of RRDR mutations in shaping physiology and antibiotic resistance, two important features of this hospital-associated pathogen.
是人类肠道微生物群的一员，已演变成一种有问题的医院病原体，是住院患者感染的主要原因。感染的治疗因抗生素耐药性而变得复杂，因此了解这种病原体的耐药机制及其更广泛的后果非常重要。在这里，我们探讨了RNA聚合酶β亚基（RpoB）中利福平耐药相关突变的附带效应。在14384个公开可用的基因组中，近三分之一在RpoB的利福平耐药决定区（RRDR）携带突变。在从一家医院的患者中收集的710株临床分离株的本地群体中，我们发现RRDR突变的存在与先前接触利福霉素抗生素之间存在显著关联，以及RRDR突变与达托霉素敏感性改变之间的关联。为了研究RRDR突变的表型影响，我们生成并研究了四种具有不同RRDR突变（Q473K、G482D、H486Y、S491L）的同基因菌株，这些突变与临床分离株变体重叠。转录组学和表型分析揭示了等位基因对基因表达、生长动力学、抗生素敏感性、异丙醇耐受性和细胞壁生理学的特异性影响。一种经常观察到的突变H486Y在抗生素应激下引起最小的转录变化并增强细菌适应性。相比之下，S491L突变诱导广泛的转录变化并减缓细菌生长，但也赋予了更高的异丙醇耐受性，可能增强细菌在医院环境中的生存能力。总体而言，我们的研究结果突出了RRDR突变在塑造生理学和抗生素耐药性方面的多方面影响，这是这种医院相关病原体的两个重要特征。
