Shahid Sadoughi University of Medical Sciences https://en.ssu.ac.ir/publications/ Advances in Pharmacology and Therapeutics Journal 2783-3445 3 2 2023 08 01 Synergistic Activity of Cressa cretica Extract Combination with Ampicillin against Klebsiella pneumoniae 66 74 327 10.18502/aptj.v3i2.13458 EN Zakaria Bameri Mehdi Fattahi_Bafghie Rahele Zareshahi Mohsen Zabihi Journal Article 2023 04 03 <strong>Aims:</strong> This study was conducted to evaluate the synergistic effect of ethanolic extract of <em>Cressa cretica</em> and ampicillin against the standard and multidrug-resistant (MDR) strains of <em>Klebsiella pneumoniae</em>.<br /><strong>Method:</strong> The chemical composition of the ethanolic extract of <em>C. cretica</em> was determined by high-performance liquid chromatography (HPLC). The minimum inhibitory concentration (MIC) of the extract was used to evaluate the antimicrobial performance of the extract. The checkboard broth method was used to investigate the synergistic effect of the extract with ampicillin.<br /><strong>Results:</strong> The ethanolic extract of <em>C. cretica</em> inhibited the growth of the standard strain of <em>K. pneumoniae</em> with MIC 100 mg/mL and did not affect the MDR strains of <em>K. pneumoniae</em>. The Fractional inhibitory concentration (FIC) showed an additive effect of ampicillin in combination with <em>C. cretica</em> on the standard strain of <em>K. pneumoniae</em>. The MIC of ampicillin in combination with <em>C. cretica</em> was reduced eightfold.<br /><strong>Conclusion:</strong> <em>C. cretica</em> ethanolic extract is containing chlorogenic acid, rutin, and catechin. The extract in combination with ampicillin can reduce the minimum inhibitory concentration of ampicillin. <em>C. cretica</em> ethanolic extract can reduce the ampicillin dosage in the treatment of Klebsiella-induced infections.  https://aptjournal.ssu.ac.ir/article_327_84d4625ec407ee855d9a970dfc811ac5.pdf