Ann Clin Microbiol.  2020 Mar;23(1):11-20. 10.5145/ACM.2020.23.1.11.

Evaluation of Synergistic Effect of Combined Treatment with Linalool and Colistin on Multidrug-Resistant Acinetobacter baumannii to Expand Candidate for Therapeutic Option

Affiliations
  • 1Department of Laboratory Medicine, College of Medicine, Chosun University, Gwangju, Republic of Korea. sjbjang@chosun.ac.kr
  • 2Premedical Science, College of Medicine, Chosun University, Gwangju, Republic of Korea.
  • 3Department of Laboratory Medicine and Research Institute of Antimicrobial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea.
  • 4Department of Internal Medicine, College of Medicine, Chosun University, Gwangju, Republic of Korea.
  • 5Department of Medical Education, College of Medicine, Chosun University, Gwangju, Republic of Korea.
  • 6Department of Urology, College of Medicine, Chosun University, Gwangju, Republic of Korea.
  • 7Korean Collection for Oral Microbiology and Department of Oral Biochemistry, College of Dentistry, Chosun University, Gwang-Ju, Republic of Korea.

Abstract

BACKGROUND
Acinetobacter baumannii infection is a significant health problem worldwide due to increased drug resistance. The limited antimicrobial alternatives for the treatment of severe infections by multidrug-resistant A. baumannii (MDRAB) make the search for other therapeutic options more urgent. Linalool, the major oil compound in Coriandrum sativum, was recently found to have high antibacterial activity against A. baumannii. The purpose of this study was to investigate the synergistic effect of linalool and colistin combinations against MDRAB and extensively drug-resistant A. baumannii (XDRAB).
METHODS
A total of 51 strains of A. baumannii clinical isolates, consisting of 10 MDRAB and 41 XDRAB were tested. We determined the minimum inhibitory concentration (MIC) of linalool for the test strains using the broth microdilution method and searched for interactions using the time-kill assay.
RESULTS
The time-kill assay showed that the linalool and colistin combination displayed a high rate of synergy (92.1%) (by synergy criteria 2), low rate of indifference (7.8%), and a high rate of bactericidal activity (74.5%) in the 51 clinical isolates of A. baumannii. The synergy rates for the linalool and colistin combination against MDRAB and XDRAB were 96% and 92.1%, respectively. No antagonism was observed for the linalool and colistin combination.
CONCLUSION
The combination of linalool and colistin showed a high synergy rate, which may be beneficial for controlling MDRAB infections. Therefore, this combination is a good candidate for in vivo studies to assess its efficacy in the treatment of MDRAB infections.

Keyword

Time-kill assay; Synergy; Linalool; Colistin; Acinetobacter baumannii
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