Department of Computer Science and Information Engineering, National Chung Cheng University, Chiayi, Taiwan.
Division of Infectious Diseases, Department of Internal Medicine, Taichung Veterans General Hospital, 1650, Section 4, Taiwan Blvd, Xitun District, Taichung, 40705, Taiwan.
Ann Clin Microbiol Antimicrob. 2024 Nov 20;23(1):102. doi: 10.1186/s12941-024-00759-3.
This study elucidates the in vivo genetic mechanisms contributing to the emerging resistance to carbapenem in Shewanella algae through a lens of adaptive microbial evolution. Leveraging PacBio amplification-free sequencing, we tracked the evolution of β-lactam resistance in clinical isolates from a persistent S. algae bacteremia case amidst antimicrobial therapy. Our investigation spotlighted a recurrent G547W mutation in the sensor histidine kinase (pdsS), which was associated with the overexpression of an OmpA-like protein (pdsO) within a proteobacteria-specific sortase system. Intriguingly, we observed a recurrent switch between wild-type and G547W alleles, revealing an adaptive expansion and contraction of underlying cell subpopulations in response to β-lactam exposure. Comparative transcriptome analyses further demonstrated the overexpression of genes pivotal for membrane integrity, biofilm formation, immune evasion, and β-lactamase activation in resistant samples. This underscores the pre-existence of resistant cells at minuscule frequencies even without antibiotic pressure, potentially explaining the within-host emergence of resistance during antibiotic treatments. Our findings provide pivotal insights into the dynamic genetic adaptations of S. algae under therapeutic pressures, unmasking intricate resistance mechanisms and highlighting the critical role of subpopulation dynamics in treatment outcomes.
本研究通过适应性微生物进化的视角，阐明了导致粘细菌对碳青霉烯类抗生素产生获得性耐药的体内遗传机制。利用 PacBio 无扩增测序，我们在抗菌治疗期间追踪了来自持续粘细菌菌血症病例的临床分离株中β-内酰胺类耐药的进化。我们的研究强调了传感器组氨酸激酶（pdsS）中 G547W 突变的反复出现，该突变与一种类似于 OmpA 的蛋白（pdsO）在特定于变形菌的分选酶系统中的过度表达有关。有趣的是，我们观察到野生型和 G547W 等位基因之间反复出现的转换，揭示了对β-内酰胺暴露的细胞亚群的适应性扩展和收缩。比较转录组分析进一步证明了耐药样本中与膜完整性、生物膜形成、免疫逃避和β-内酰胺酶激活相关的关键基因的过度表达。这表明即使没有抗生素压力，耐药细胞也以微小的频率预先存在，这可能解释了抗生素治疗期间体内耐药性的出现。我们的研究结果为治疗压力下粘细菌的动态遗传适应提供了重要的见解，揭示了复杂的耐药机制，并强调了亚群动力学在治疗结果中的关键作用。
