Original ArtIcle

Evaluation of Synergistic Effect of Combined Treatment with Linalool and Colistin on Multidrug-ResistantAcinetobacter 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
3Department of Laboratory Medicine and Research Institute of Antimicrobial Resistance,Yonsei University College of Medicine
4Department of Internal Medicine
5Medical Education
6Urology College of Medicine, Chosun University
7Korean Collection for Oral Microbiology and Department of Oral Biochemistry, College of Dentistry, Chosun University


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. baumanniiA. baumannii 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. baumanniiA. baumannii A. baumannii(XDRAB).

A total of 51 strains of A. baumanniiA. baumannii A. baumanniiclinical 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.

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.

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.

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