Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisiana, USA.
Center for Women's Infectious Disease Research, Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA.
Microbiol Spectr. 2023 Aug 17;11(4):e0536522. doi: 10.1128/spectrum.05365-22. Epub 2023 Jun 28.
Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of complicated urinary tract infection (UTI) associated with the use of indwelling urinary catheters. Previous reports have revealed host and pathogen effectors critical for MRSA uropathogenesis. Here, we sought to determine the significance of specific metabolic pathways during MRSA UTI. First, we identified four mutants from the Nebraska transposon mutant library in the MRSA JE2 background that grew normally in rich medium but displayed significantly reduced growth in pooled human urine (HU). This prompted us to transduce the uropathogenic MRSA 1369 strain with the transposon mutants in and (tricarboxylic acid [TCA] cycle), (mannitol metabolism), and (pyruvate oxidation). Notably, , , and were also significantly upregulated in the MRSA 1369 strain upon exposure to HU. Compared to the WT, the MRSA 1369 mutant was significantly defective for (i) growth in HU, and (ii) colonization of the urinary tract and dissemination to the kidneys and the spleen in the mouse model of catheter-associated UTI (CAUTI), which may be attributed to its increased membrane hydrophobicity and higher susceptibility to killing by human blood. In contrast to their counterparts in the JE2 background, the , , and mutants in the MRSA 1369 background grew normally in HU; however, they displayed significant fitness defects in the CAUTI mouse model. Overall, identification of novel metabolic pathways important for the urinary fitness and survival of MRSA can be used for the development of novel therapeutics. While Staphylococcus aureus has historically not been considered a uropathogen, S. aureus urinary tract infection (UTI) is clinically significant in certain patient populations, including those with chronic indwelling urinary catheters. Moreover, most S. aureus strains causing catheter-associated UTI (CAUTI) are methicillin-resistant S. aureus (MRSA). MRSA is difficult to treat due to limited treatment options and the potential to deteriorate into life-threatening bacteremia, urosepsis, and shock. In this study, we found that pathways involved in pyruvate oxidation, TCA cycle, and mannitol metabolism are important for MRSA fitness and survival in the urinary tract. Improved understanding of the metabolic needs of MRSA in the urinary tract may help us develop novel inhibitors of MRSA metabolism that can be used to treat MRSA-CAUTI more effectively.
耐甲氧西林金黄色葡萄球菌（MRSA）是与留置导尿管相关的复杂尿路感染（UTI）的重要原因。先前的报告揭示了宿主和病原体效应物对 MRSA 尿路致病性至关重要。在这里，我们试图确定特定代谢途径在 MRSA UTI 中的意义。首先，我们从 MRSA JE2 背景下的内布拉斯加转座子突变体文库中鉴定出四个在丰富培养基中正常生长但在混合人尿（HU）中生长明显减少的突变体。这促使我们用转座子突变体转导尿路致病性 MRSA 1369 株 和 （三羧酸循环）， （甘露醇代谢）和 （丙酮酸氧化）。值得注意的是，HU 暴露后，MRSA 1369 株中的 、 和 也显著上调。与 WT 相比，MRSA 1369 突变体在（i）HU 中的生长和（ii）在导管相关尿路感染（CAUTI）小鼠模型中的尿路定植和传播到肾脏和脾脏方面明显缺陷，这可能归因于其增加的膜疏水性和对人血杀伤的更高敏感性。与 JE2 背景中的对应物相比，MRSA 1369 背景中的 、 和 突变体在 HU 中正常生长；然而，它们在 CAUTI 小鼠模型中表现出明显的适应性缺陷。总之，确定对 MRSA 尿路适应性和存活至关重要的新代谢途径可用于开发新的治疗方法。 虽然金黄色葡萄球菌（S. aureus）历来不被认为是尿路病原体，但金黄色葡萄球菌尿路感染（UTI）在某些患者群体中具有临床意义，包括那些长期留置导尿管的患者。此外，引起导管相关尿路感染（CAUTI）的大多数金黄色葡萄球菌（S. aureus）菌株都是耐甲氧西林金黄色葡萄球菌（MRSA）。由于治疗选择有限，以及可能恶化为危及生命的菌血症、尿脓毒症和休克的潜力，MRSA 很难治疗。在这项研究中，我们发现丙酮酸氧化、三羧酸循环和甘露醇代谢途径参与的途径对 MRSA 在泌尿道中的适应性和存活至关重要。更好地了解 MRSA 在泌尿道中的代谢需求可能有助于我们开发可用于更有效地治疗 MRSA-CAUTI 的新型 MRSA 代谢抑制剂。
