Find in Library

The present study aimed to investigate the antibacterial activity of ethanolic <i>Kaempferia parviflora</i> extracts and the combined effects of the plant’s specific compounds with gentamicin against clinical strains of carbapenem-resistant <i>Klebsiella pneumoniae</i>, <i>Pseudomonas aeruginosa</i>, and <i>Acinetobacter baumannii</i>. The minimal inhibitory concentrations (MIC) of gentamicin and <i>Kaempferia parviflora</i> extracts against the tested bacterial strains were determined by using broth microdilution. The combined effects of <i>Kaempferia parviflora</i> extract and gentamicin were investigated by using a checkerboard assay and expressed as a fractional inhibitory concentration index (FICI). Crude ethanolic extract of <i>Kaempferia parviflora</i> showed the lowest median values of MIC towards the tested isolates (<i>n</i> = 10) of these tested bacteria at doses of 64 µg/mL, compared to those of other <i>Kaempferia extracts</i>. Among the isolated compounds, only three compounds, namely 3,5,7-trimethoxyflavone, 3,5,7,3′4′-pentamethoxyflavone, and 5,7,4′-trimethoxyflavone, were identified by NMR structural analysis. According to their FICIs, the synergistic effects of gentamicin combined with 3,5,7,3′4′-pentamethoxyflavone were approximately 90%, 90%, and 80% of tested carbapenem-resistant <i>Klebsiella pneumoniae</i> (CRKP), <i>Pseudomonas aeruginosa</i> (CRPA), and <i>Acinetobacter baumannii</i> (CRAB), respectively. The present study concluded that 3,5,7,3′4′-pentamethoxyflavone extracted from <i>Kaempferia parviflora</i> potentiated the antibacterial action of gentamicin to combat bacterial resistance against the tested bacteria.