Ann Clin Microbiol.  2020 Mar;23(1):45-54. 10.5145/ACM.2020.23.1.45.

Role of Efflux Pump Gene adeIJK to Multidrug Resistance in Acinetobacter baumannii Clinical Isolates

  • 1Division of Antimicrobial Resistance, Center for Infectious Diseases Research, Korea National Institute of Health, KCDC, Cheongju, Republic of Korea.
  • 2Premedical Science, College of Medicine, Chosun University Hospital, Gwangju, Republic of Korea.
  • 3Department of Laboratory Medicine, College of Medicine, Chosun University Hospital, Gwangju, Republic of Korea.
  • 4Department of Laboratory Medicine, Chosun University Hospital, Gwangju, Republic of Korea.
  • 5Department of Otolaryngology, Chonnam National University Medical School, Gwangju, Republic of Korea.


The emergence of multidrug-resistant Acinetobacter baumannii as a nosocomial pathogen is one of the major public health problems. The aim of this study was to evaluate the role of an efflux pump gene adeJ for the multidrug resistance of A. baumannii clinical isolates.
Two groups (MDRAB and SAB) of A. baumannii clinical isolates were studied. The SAB group consisted of strains that did not meet the criteria of MDRAB and were susceptible to more categories of antibiotics than MDRAB. Antimicrobial susceptibility results obtained by VITEKII system were used in data analysis and bacterial group allocation. We performed real-time reverse transcription PCR to determine relative expression of adeJ. We compared relative expression of adeJ in comparison groups by considering two viewpoints: i) MDRAB and SAB groups and ii) susceptible and non-susceptible groups for each antibiotic used in this study.
The mean value of relative expression of adeJ of MDRAB and SAB groups was 1.4 and 0.92, respectively, and showed significant difference (P=0.002). The mean values of relative expression of adeJ of susceptible and non-susceptible groups to the antibiotics cefepime, ceftazidime, ciprofloxacin, imipenem, meropenem, tigecycline, piperacillin/tazobactam, ticarcillin/clavulanic acid, trimethoprim/sulfamethoxazole, piperacillin, and gentamicin showed statistically significant differences.
The overexpression of adeIJK might contribute to the multi-drug resistance in A. baumannii clinical isolates. Further, the overexpression of adeIJK might be one of the factors contributing to the resistance to numerous antibiotics.


Multidrug resistance; Efflux; adeJ gene; Acinetobacter baumannii

MeSH Terms

Acinetobacter baumannii*
Anti-Bacterial Agents
Drug Resistance, Multiple*
Polymerase Chain Reaction
Public Health
Reverse Transcription
Statistics as Topic
Anti-Bacterial Agents


  • Fig. 1. Relative expression of the adeJ efflux pump gene determined by real-time reverse transcriptase PCR in A. baumannii type strain (ATCC19606), multidrug resistant A. baumannii AYE strain, 70 strains of multidrug resistant A. baumannii (MDRAB) and 30 strains of non-MDRAB clinical isolates. The normalized expression of adeJ was calibrated with the expression of A. baumannii ATCC 19606. The error bars represent the standard error of the mean. *P < 0.05.

  • Fig. 2. Relationship between adeJ pump gene expression and resistance to each antibiotics. Relative expression of adeJ efflux pump gene in non-susceptible (NS) group was higher than that of susceptible (S) group to each antibiotics in general. The statistically significant difference was found between S and NS groups to cefepime, cefotaxime, ceftazidime, ciprofloxacin, gentamicin, imipenem, meropenem, piperacillin, piperacillin/tazobactam, ticarcillin/clavulanic acid, tigecycline, and trimethoprim/sulfamethoxazole, respectively. *P < 0.05, **P < 0.001. The error bars represent the standard error of the mean.



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