Amin Muhammad Usman, Khurram Muhammad, Khattak Baharullah, Khan Jafar
Department of Microbiology, Kohat University of Science and Technology, Kohat, KP, Pakistan.
Department of Pharmacy, Shaheed Benazir Bhutto University, Sheringal, Dir Upper, KP, Pakistan.
BMC Complement Altern Med. 2015 Mar 12;15:59. doi: 10.1186/s12906-015-0580-0.
To determine the effect of flavonoids in conjunction with antibiotics in methicillin resistant Staphylococcus aureus (MRSA) a study was designed. The flavonoids included Rutin, Morin, Qurecetin while antibiotics included ampicillin, amoxicillin, cefixime, ceftriaxone, vancomycin, methicillin, cephradine, erythromycin, imipenem, sulphamethoxazole/trimethoprim, ciprofloxacin and levolfloxacin. Test antibiotics were mostly found resistant with only Imipenem and Erythromycin found to be sensitive against 100 MRSA clinical isolates and S. aureus (ATCC 43300). The flavonoids were tested alone and also in different combinations with selected antibiotics.
Antibiotics and flavonoids sensitivity assays were carried using disk diffusion method. The combinations found to be effective were sifted through MIC assays by broth macro dilution method. Exact MICs were determined using an incremental increase approach. Fractional inhibitory concentration indices (FICI) were determined to evaluate relationship between antibiotics and flavonoids is synergistic or additive. Potassium release was measured to determine the effect of antibiotic-flavonoids combinations on the cytoplasmic membrane of test bacteria.
Antibiotic and flavonoids screening assays indicated activity of flavanoids against test bacteria. The inhibitory zones increased when test flavonoids were combined with antibiotics facing resistance. MICs of test antibiotics and flavonoids reduced when they were combined. Quercetin was the most effective flavonoid (MIC 260 μg/ml) while morin + rutin + quercetin combination proved most efficient with MIC of 280 + 280 + 140 μg/ml. Quercetin + morin + rutin with amoxicillin, ampicillin, cephradine, ceftriaxone, imipenem, and methicillin showed synergism, while additive relationship was indicated between morin + rutin and amoxicillin, cephradine, ceftriaxone, imipenem, and methicillin. Quercetin alone had an additive effect with ampicillin, cephradine, ceftriaxone, imipenem, and methicillin. Potassium leakage was highest for morin + rutin + quercetin that improved further in combination with imipenem. Morin and rutin alone had no activity but in combination showed activity against test bacteria.
The flavonoids when used in combination with antibiotics were found to increase each other activity against test bacteria. The relationship between the flavonoids and antibiotics in most of the cases was additive. However in a few cases synergism was also observed. Flavonoids alone or in combinations also damaged bacterial cell membrane.
为了确定黄酮类化合物与抗生素联合使用对耐甲氧西林金黄色葡萄球菌（MRSA）的影响，设计了一项研究。黄酮类化合物包括芦丁、桑色素、槲皮素，而抗生素包括氨苄西林、阿莫西林、头孢克肟、头孢曲松、万古霉素、甲氧西林、头孢拉定、红霉素、亚胺培南、磺胺甲恶唑/甲氧苄啶、环丙沙星和左氧氟沙星。测试的抗生素大多具有耐药性，仅发现亚胺培南和红霉素对100株MRSA临床分离株和金黄色葡萄球菌（ATCC 43300）敏感。黄酮类化合物单独进行了测试，也与选定的抗生素进行了不同组合的测试。
采用纸片扩散法进行抗生素和黄酮类化合物敏感性测定。通过肉汤宏观稀释法的MIC测定筛选出有效的组合。使用增量增加法确定确切的MIC。测定分数抑制浓度指数（FICI）以评估抗生素和黄酮类化合物之间的关系是协同还是相加。测量钾释放以确定抗生素-黄酮类化合物组合对测试细菌细胞质膜的影响。
抗生素和黄酮类化合物筛选测定表明黄酮类化合物对测试细菌有活性。当测试黄酮类化合物与耐药抗生素联合使用时，抑菌圈增大。测试抗生素和黄酮类化合物联合使用时MIC降低。槲皮素是最有效的黄酮类化合物（MIC为260μg/ml），而桑色素+芦丁+槲皮素组合被证明最有效，MIC为280 + 280 + 140μg/ml。槲皮素+桑色素+芦丁与阿莫西林、氨苄西林、头孢拉定、头孢曲松、亚胺培南和甲氧西林显示出协同作用，而桑色素+芦丁与阿莫西林、头孢拉定、头孢曲松、亚胺培南和甲氧西林之间显示出相加关系。单独的槲皮素与氨苄西林、头孢拉定、头孢曲松、亚胺培南和甲氧西林具有相加作用。桑色素+芦丁+槲皮素的钾泄漏最高，与亚胺培南联合使用时进一步增加。单独的桑色素和芦丁没有活性，但联合使用时对测试细菌有活性。
发现黄酮类化合物与抗生素联合使用时会增加彼此对测试细菌的活性。在大多数情况下，黄酮类化合物与抗生素之间的关系是相加的。然而，在少数情况下也观察到了协同作用。单独或组合使用的黄酮类化合物也会损害细菌细胞膜。
