苯唑西林敏感的耐甲氧西林金黄色葡萄球菌(OS-MRSA)的出现对MRSA感染的临床管理提出了进一步的挑战。当暴露于β-内酰胺抗生素时,这些菌株很容易通过染色体突变获得降低的β-内酰胺敏感性,包括RNA聚合酶(RNAP)基因,如rpoBC,这可能会导致治疗失败。尽管此类菌株的流行率越来越高,并且它们对诊断和治疗构成了明显的挑战,关于这种与染色体突变相关的转变为β-内酰胺敏感性降低的实际机制的信息有限。因为它不直接与mecA的表达式相关联。这项研究调查了六种具有降低的苯唑西林敏感性的错义突变体的细胞生理和代谢,每个在RpoBH929P上携带各自的突变,RpoBQ645H,RpoCG950R,RpoCG498D,RpiAA64E,和FruBA211E,使用基于毛细管电泳-质谱的代谢组学分析。我们的结果显示rpoBC突变导致RNAP转录功能障碍,导致核糖核苷酸的细胞内积累。这些突变也导致UDP-Glc/Gal和UDP-GlcNAc的积累,它们是UTP相关肽聚糖和壁磷壁酸的前体。过量的结构单元会导致突变菌株的细胞壁增厚,正如在透射电子显微镜中观察到的那样,并最终导致OS-MRSA对β-内酰胺的敏感性降低。
目的:苯唑西林敏感的耐甲氧西林金黄色葡萄球菌(OS-MRSA)菌株的出现为MRSA感染的治疗带来了新的挑战。这些菌株可以通过染色体突变对β-内酰胺类抗生素产生耐药性,包括RNA聚合酶(RNAP)基因中的那些,如rpoBC,导致治疗失败。这项研究调查了OS-MRSA的四种rpoBC突变体中降低β-内酰胺敏感性的潜在机制。结果表明,rpoBC突变导致RNAP转录功能障碍,导致核糖核苷酸和肽聚糖前体以及壁磷壁酸的细胞内积累。这个,反过来,导致细胞壁增厚,并最终导致OS-MRSA中对β-内酰胺的敏感性降低。这些发现为OS-MRSA中抗生素耐药性的机制提供了见解,并强调了持续研究在开发有效治疗以对抗抗生素耐药性方面的重要性。
The emergence of oxacillin-susceptible methicillin-resistant Staphylococcus aureus (OS-MRSA) has imposed further challenges to the clinical management of MRSA infections. When exposed to β-lactam antibiotics, these strains can easily acquire reduced β-lactam susceptibility through chromosomal mutations, including those in RNA polymerase (RNAP) genes such as rpoBC, which may then lead to treatment failure. Despite the increasing prevalence of such strains and the apparent challenges they pose for diagnosis and treatment, there is limited information available on the actual mechanisms underlying such chromosomal mutation-related transitions to reduced β-lactam susceptibility, as it does not directly associate with the expression of mecA. This study investigated the cellular physiology and metabolism of six missense mutants with reduced oxacillin susceptibility, each carrying respective mutations on RpoBH929P, RpoBQ645H, RpoCG950R, RpoCG498D, RpiAA64E, and FruBA211E, using capillary electrophoresis-mass spectrometry-based metabolomics analysis. Our results showed that rpoBC mutations caused RNAP transcription dysfunction, leading to an intracellular accumulation of ribonucleotides. These mutations also led to the accumulation of UDP-Glc/Gal and UDP-GlcNAc, which are precursors of UTP-associated peptidoglycan and wall teichoic acid. Excessive amounts of building blocks then contributed to the cell wall thickening of mutant strains, as observed in transmission electron microscopy, and ultimately resulted in decreased susceptibility to β-lactam in OS-MRSA.
OBJECTIVE: The emergence of oxacillin-susceptible methicillin-resistant Staphylococcus aureus (OS-MRSA) strains has created new challenges for treating MRSA infections. These strains can become resistant to β-lactam antibiotics through chromosomal mutations, including those in the RNA polymerase (RNAP) genes such as rpoBC, leading to treatment failure. This study investigated the mechanisms underlying reduced β-lactam susceptibility in four rpoBC mutants of OS-MRSA. The results showed that rpoBC mutations caused RNAP transcription dysfunction, leading to an intracellular accumulation of ribonucleotides and precursors of peptidoglycan as well as wall teichoic acid. This, in turn, caused thickening of the cell wall and ultimately resulted in decreased susceptibility to β-lactam in OS-MRSA. These findings provide insights into the mechanisms of antibiotic resistance in OS-MRSA and highlight the importance of continued research in developing effective treatments to combat antibiotic resistance.