Enhanced Antibacterial Activity of Meropenem against Extensively Drug-Resistant Acinetobacter baumannii by Myrtaceae Plant Extracts


  • Dennapa SAELOH Faculty of Medical Technology, Prince of Songkla University, Songkhla 90110, Thailand
  • Monton VISUTTHI Biology Program, Faculty of Science and Technology, Nakhon Ratchasima Rajabhat University, Nakhon Ratchasima 30000, Thailand
  • Marisa LEEHA Division of Health and Applied Sciences, Faculty of Science, Prince of Songkla University, Songkhla 90110, Thailand
  • Surasak LIMSUWAN Faculty of Traditional Thai Medicine, Prince of Songkla University, Songkhla 90110, Thailand
  • Supayang Piyawan VORAVUTHIKUNCHAI Natural Product Research Center of Excellence, Prince of Songkla University, Songkhla 90110, Thailand




Acinetobacter baumannii, Combination, Meropenem, Myrtaceae


Acinetobacter baumannii (A. baumannii) has been known as a major cause of nosocomial bacterial infections worldwide. The bacteria are increasingly associated with a broad spectrum of antibiotic resistance, and this has become a widespread concern in a variety of hospitals.Antibiotic development and alternative treatment have become priorities for the treatment of bacterial infections.This study investigated the efficacy of meropenem in combination with five ethanolic extracts of plants in Myrtaceae against extensively drug-resistant (XDR) A. baumannii. The resistant phenotype was previously determined by microdilution method. XDR-A. baumannii strains showed resistance to meropenem with the minimum inhibitory concentration (MIC) in a range of 16 - 128 µg/mL, whereas the MIC value of all extracts, including Calistemon lancealatus, Eucalyptus citridora, Rhodomytus tomentasa, Syzygium cumini, and Xanthortemon chrysanthus, was over 1,000 µg/mL. Interestingly, all extracts potentiated the activity of the antibiotic by reducing the MIC values of the antibiotic. Xanthortemon chrysanthus extract displayed excellent synergism against the bacteria by decreasing the MIC value of the drug greater than 8-fold. In addition, the extract, at concentrations of 31.25, 62.5, 125, 250, 500, and 1,000 µg/mL, obviously increased the inhibitory effect of meropenem (1/4´MIC) against A. baumannii. The percentage of bacterial growth inhibition by combination was 87.9, 88.8, 91.8, 93.6, 99.9, and 100, respectively. The results supported that the extract could improve the activity of ineffective antibiotics against drug-resistant pathogens.Therefore, the findings may serve as therapeutic options for XDR-A. baumannii infections in the future.


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How to Cite

SAELOH, D. ., VISUTTHI, M. ., LEEHA, M. ., LIMSUWAN, S. ., & VORAVUTHIKUNCHAI, S. P. . (2020). Enhanced Antibacterial Activity of Meropenem against Extensively Drug-Resistant Acinetobacter baumannii by Myrtaceae Plant Extracts. Walailak Journal of Science and Technology (WJST), 17(11), 1168–1176. https://doi.org/10.48048/wjst.2020.10714