Original ArtIcle

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

Ji Ae  Choi1   Choon-Mee  Kim2   Sook-Jin  Jang3 *   Seong-Sik  Cho4   Chul Ho  Jang5   Young-Jin  Ko3   Kang Seong-Ho3   Park Geon 3   

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


The emergence of multidrug-resistant Acinetobacter baumanniias 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. baumanniiclinical isolates.

Two groups (MDRAB and SAB) of A. baumanniiclinical 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. baumanniiclinical isolates. Further, the overexpression of adeIJK might be one of the factors contributing to the resistance to numerous antibiotics.

Figures & Tables

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. baumanniiATCC 19606. The error bars represent the standard error of the mean. *P < 0.05.