Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology

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pISSN 2288-0585 eISSN 2288-6850

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

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2020 March, Volume 23, Issue 1, pages 11-20.

https://doi.org/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

Ung-Jun Kim1, Choon-Mee Kim2, Sook-Jin Jang1, Seul-Bi Lee1, Seong-Sik Cho1, Seok-Hoon Jeong3, Young-Jin Ko1, Seong-Ho Kang1, Geon Park1, Dong-Min Kim4, Na-Ra Yoon4, Young-Joon Ahn5, Donghoon Lim6, Joong-Ki Kook7
1Department of Laboratory Medicine, 2Premedical Science, College of Medicine, Chosun University, Gwangju, 3Department of Laboratory Medicine and Research Institute of Antimicrobial Resistance, Yonsei University College of Medicine, Seoul, Department of 4Internal Medicine, 5Medical Education, 6Urology, College of Medicine, Chosun University, Gwangju, 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.

Conclusions: 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.

Keywords

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