Talinum fruticosum (L.) Juss. (Talinaceae), an Edible and Medicinal Plant, Enhances the Activity of Antibiotics Against Multidrug-Resistant Gram-Negative Bacteria

The rapid acquisition of multidrug-resistant (MDR) phenotypes by bacteria creates life-threatening complications in infection control. Accordingly, this study aims to investigate the antibacterial activity of the methanol extract of Talinum fruticosum leaves and its interaction effects with antibiotics against MDR Gram-negative bacteria. The broth microdilution method was used to evaluate the antibacterial activity and antibiotic-resistance modulation effects of the extract. The interaction between antibiotics and T. fruticosum leaf extract (TFLE) was conducted using the checkerboard assay. Phytochemical screening was assessed using standardized qualitative tests. TFLE displayed low antibacterial activity, with MICs ranging from 512 to 2048 µg/mL against the tested bacteria. Interestingly, TFLE at its subinhibitory concentration (MIC/8) enhanced the efficacy of antibiotics by 2-to 64-fold, particularly tetracycline, doxycycline, imipenem, kanamycin, and ciprofloxacin, against at least one of the examined MDR bacteria. In addition, TFLE displayed a synergistic effect (ƩFIC < 0.5) with kanamycin and doxycycline against K. pneumoniae K2 and E. aerogenes EA298. The phytochemical screening indicated that TFLE contained flavonoids, saponins, tannins, terpenoids, phenols, and anthocyanins. Overall, this study shows that T. fruticosum leaf extract could be used in combination with commonly used antibiotics to fight infections involving MDR bacteria. Therefore, further studies are needed to identify in this plant a likely nontoxic antibiotic modulator.