Gu Siyao, Fan Bing, Wan Fang, Gao Tong, Qi Yuanyuan, Zhou Jin, Zhang Yaou, Gu Dayong, Xie Weidong
State Key Laboratory of Chemical Oncogenomics, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
Open FIESTA Center, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
Molecules. 2023 Jul 26;28(15):5668. doi: 10.3390/molecules28155668.
Diabetic foot infection (DFI) is a common complication in diabetes patients, with foot infections being the leading cause of amputations. is frequently found in diabetic foot infections, of which methicillin-resistant (MRSA) has become a major clinical and epidemiological challenge. Since MRSA strains are resistant to most β-lactam antibiotics, and also partially resistant to other antibiotics, treatment is difficult and costly. The emergence of drug-resistant bacteria often arises from overuse or misuse of antibiotics. Clinically, canagliflozin is commonly used for the treatment of type 2 diabetes. On this basis, we investigated the antibacterial activity and mechanism of canagliflozin against MRSA, with the aim to discover novel functions of canagliflozin and provide new insights for the treatment of MRSA. Using the microbroth dilution method to determine the half maximal inhibitory concentration of drugs, we found that canagliflozin not only can inhibit the growth of methicillin-sensitive (MSSA) but also exhibits antibacterial activity against MRSA. The IC50 values, at approximately 56.01 μM and 57.60 μM, were almost the same. At 12 h, canagliflozin showed a significant antibacterial effect against MRSA at and above 30 μM. In addition, its combined use with penicillin achieved better antibacterial effects, which were increased by about three times. Additive antibacterial activity (FICI = 0.69) was found between penicillin and canagliflozin, which was better than that of doxycycline and canagliflozin (FICI = 0.95). Canagliflozin also affected bacterial metabolic markers, such as glucose, ATP, and lactic acid. The results of crystal violet staining indicate that canagliflozin disrupted the formation of bacterial biofilm. Our electron microscopy results showed that canagliflozin distorted the bacterial cell wall. The results of RT-PCR suggest that canagliflozin down-regulated the expressions of biofilm-related gene (clfA, cna, agrC, mgrA, hld) and methicillin-resistance gene (mecA), which was related to MRSA. Molecular docking also indicated that canagliflozin affected some interesting targets of MRSA, such as the sarA, crtM and fnbA proteins. In conclusion, canagliflozin exhibits antibacterial activity against MRSA by affecting bacterial metabolism, inhibiting its biofilm formation, distorting the bacterial cell wall, and altering the gene expression of biofilm formation and its virulence. Our study reveals the antibacterial activity of canagliflozin against MRSA, providing a new reference for treating diabetic foot infections.
糖尿病足感染（DFI）是糖尿病患者常见的并发症，足部感染是截肢的主要原因。耐甲氧西林金黄色葡萄球菌（MRSA）在糖尿病足感染中很常见，已成为主要的临床和流行病学挑战。由于MRSA菌株对大多数β-内酰胺类抗生素耐药，且对其他抗生素也部分耐药，治疗困难且成本高昂。耐药菌的出现往往源于抗生素的过度使用或滥用。临床上，卡格列净常用于治疗2型糖尿病。在此基础上，我们研究了卡格列净对MRSA的抗菌活性及其机制，旨在发现卡格列净的新功能，为MRSA的治疗提供新的思路。采用微量肉汤稀释法测定药物的半数最大抑菌浓度，我们发现卡格列净不仅能抑制甲氧西林敏感金黄色葡萄球菌（MSSA）的生长，还对MRSA具有抗菌活性。其IC50值分别约为56.01μM和57.60μM，几乎相同。在12小时时，卡格列净在30μM及以上浓度对MRSA显示出显著的抗菌效果。此外，它与青霉素联合使用具有更好的抗菌效果，抗菌效果提高了约三倍。青霉素和卡格列净之间表现出相加抗菌活性（FICI = 0.69），优于强力霉素和卡格列净（FICI = 0.95）。卡格列净还影响细菌的代谢标志物，如葡萄糖、ATP和乳酸。结晶紫染色结果表明卡格列净破坏了细菌生物膜的形成。我们的电子显微镜结果显示卡格列净使细菌细胞壁变形。RT-PCR结果表明卡格列净下调了与MRSA相关的生物膜相关基因（clfA、cna、agrC、mgrA、hld）和耐甲氧西林基因（mecA）的表达。分子对接也表明卡格列净影响了MRSA的一些有趣靶点，如sarA、crtM和fnbA蛋白。总之，卡格列净通过影响细菌代谢、抑制其生物膜形成、使细菌细胞壁变形以及改变生物膜形成及其毒力的基因表达，对MRSA表现出抗菌活性。我们的研究揭示了卡格列净对MRSA的抗菌活性，为治疗糖尿病足感染提供了新的参考。
