Laboratory of Semi-Arid Bioprospecting (LABSEMA), Department of Biological Chemistry - URCA, Crato, CE, 63105-000, Brazil.
Graduate Program in Biological Sciences, Federal University of Pernambuco - UFPE, Recife, PE, 50740-600, Brazil.
Biol Open. 2022 Oct 15;11(10). doi: 10.1242/bio.059434. Epub 2022 Oct 7.
The Gram-positive bacterium Staphylococcus aureus is responsible for a number of infections and has been described to exhibit resistance to antibacterial drugs through different resistance mechanisms. Among these, active efflux has been shown to be one of the main mechanisms of bacterial resistance associated with S. aureus. In this sense, the aim of the present study was to evaluate the ability of ellagic acid and gallic acid to reverse resistance by inhibiting the efflux pumps present in S. aureus strains IS-58 and K2068, which express the TetK and MepA flux pumps, respectively. In addition, the toxicity of both compounds was verified in Drosophila melanogaster. Broth microdilution assays were performed to obtain the minimum inhibitory concentration (MIC) values of ellagic acid and gallic acid, whereas efflux pump inhibition was tested using a subinhibitory concentration of standard efflux pump inhibitors, gallic acid and ellagic acid (MIC/8), where the ability of these compounds to decrease the MIC of ethidium bromide (EtBr) and antibiotics was verified. Toxicity was evaluated by mortality and negative geotaxis assays in D. melanogaster. Ellagic acid and gallic acid showed no direct antibacterial activity on S. aureus strains carrying the efflux pumps TetK and MepA. However, when we looked at the results for the TetK pump, we saw that when the two acids were associated with the antibiotic tetracycline, a potentiation of the antibacterial effect occurred; this behavior was also observed for the antibiotic ciprofloxacin in the MepA strain. For the efflux pump inhibition results, only the compound gallic acid showed potentiating effect on antibacterial activity when associated with the substrate EtBr for the IS-58 strain carrying the TetK efflux pump. Ellagic acid and gallic acid showed no toxicity on the model arthropod D. melanogaster. These results indicate the possible use of gallic acid as an adjuvant in antibiotic therapy against multidrug-resistant bacteria.
革兰氏阳性菌金黄色葡萄球菌可引起多种感染，并且已被证实通过不同的耐药机制对抗菌药物产生耐药性。其中，主动外排已被证明是与金黄色葡萄球菌相关的细菌耐药的主要机制之一。在这种意义上，本研究的目的是评估鞣花酸和没食子酸抑制金黄色葡萄球菌菌株 IS-58 和 K2068 中表达的 TetK 和 MepA 外排泵来逆转耐药的能力，这两种菌株分别表达 TetK 和 MepA 外排泵。此外，还在黑腹果蝇中验证了这两种化合物的毒性。采用肉汤微量稀释法测定鞣花酸和没食子酸的最低抑菌浓度（MIC）值，并用标准外排泵抑制剂没食子酸和鞣花酸（MIC/8）的亚抑菌浓度测试外排泵抑制作用，验证了这两种化合物降低溴化乙锭（EtBr）和抗生素 MIC 的能力。采用黑腹果蝇的死亡率和负趋地性试验评估毒性。鞣花酸和没食子酸对携带 TetK 和 MepA 外排泵的金黄色葡萄球菌菌株没有直接的抗菌活性。然而，当我们观察 TetK 泵的结果时，我们发现当两种酸与抗生素四环素联合使用时，会增强抗菌作用；在携带 MepA 外排泵的 IS-58 菌株中，这种行为也观察到了对环丙沙星的抗生素作用。对于外排泵抑制结果，只有化合物没食子酸在与 TetK 外排泵携带的底物 EtBr 相关联时，对 IS-58 菌株的抗菌活性表现出增效作用。鞣花酸和没食子酸对模式节肢动物黑腹果蝇没有毒性。这些结果表明，没食子酸可能作为一种辅助抗生素治疗多药耐药菌的方法。
