Association between mutations in gyrA and parC genes of Acinetobacter baumannii clinical isolates and ciprofloxacin resistance


1 Department of Microbiology, Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran

2 Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran

3 Department of Microbiology, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran

4 Department of Science and Environment, Faculty of Science, Technology and Communication, Luxembourg University and Faculty of Science and Environment University of Liege, Liege, Belgium


Objective(s): We investigated the contribution of gyrA and parC mutational mechanism in decreased ciprofloxacin susceptibility of Acinetobacter baumannii isolated from burn wound infections.
Materials and Methods: Ciprofloxacin susceptibility of 50 A. baumannii isolates was evaluated by disk diffusion and agar dilution methods. PCR and sequencing were performed for detection of mutation in gyrA and parC genes.
Results: The 44 and 4 isolates of A. baumannii exhibited full and intermediate-resistant to ciprofloxacin, respectively. Overall, the 42 isolates with double mutations of gyrA and parC genes showed a higher level of ciprofloxacin resistance than the 3 isolates with single mutations of gyrA or parC.
Conclusion: Simultaneous mutations in gyrA and parC genes are expected to play a major role in high-level fluoroquinolone resistance in A. baumannii; albeit a single mutation in DNA topoisomerase IV could occasionally be associated with intermediate-resistance to these antimicrobials.


1.  Boucher  HW,  Talbot  GH,  Bradley  JS,  Edwards  JE,  Gilbert  D,  Rice  LB, et al. Bad bugs, no drugs:  no ESKAPE! An update from the Infectious Diseases Society of America. Clin Infect Dis 2009; 48:1-12.

2. Towner KJ, Levi K, Vlassiadi M. Genetic diversity of carbapenem-resistant isolates of Acinetobacterbaumannii in Europe. Clin Microbiol Infect 2008; 14:161-167.

3.  Ardebili A, Talebi M, Azimi L, Lari AR.  Effect  of  efflux  pump  inhibitor  CCCP  on  the  MIC  of  ciprofloxacin  in  Acinetobacter  baumannii  clinical  isolates. Jundishapur J Microbiol 2014; 7:doi:10.5812/jjm.8691.

4. Valentine SC, Contreras D, Tan S, Real LJ, Chu  S, Xu HH. Phenotypic and molecular characterization of Acinetobacter baumannii clinical isolates from nosocomial outbreaks in Los Angeles County,  California.  J  Clin Microbiol 2008; 46:2499-2507.

5. Jacoby GA. Mechanisms of resistance to quinolones. Clin Infect Dis 2005; 41:120-126.

6. Fàbrega A, Madurga S, Giralt E, Vila J. Mechanism of action of and resistance to quinolones. Microbial Biotech 2009; 2:40-61.

7. Lee JK, Lee YS, Park YK, Kim BS. Mutations in the gyrA and parC genes in ciprofloxacin-resistant clinical isolates of Acinetobacter baumannii in Korea. MicrobiolImmunol 2005; 49:647-653.

8. Mostofi S, Mirnejad R, Masjedian F.Multi-drug resistance in Acinetobacter baumannii strains isolated from clinical specimens from three hospitals in Tehran, Iran. Afr J Microbiol Res 2011; 5:3579-3582.

9. Rahbar M, Mehrgan H, Negar HA. Prevalence of antibiotic-resistant Acinetobacter baumannii in a 1000-bed tertiary care hospital in Tehran, Iran. Ind J Pathol Microbiol  2010; 53:290-293.

10. Turton JF, Woodford N, Glover J, Yarde S, Kaufmann ME, Pitt TL. Identification of Acinetobacter baumannii by detection of the blaOXA-51-like carbapenemase gene intrinsic to this species. J Clin Microbiol 2006; 44:2974-2976.

11. CLSI, Performance standards for antimicrobial susceptibility testing:twentieth informational supplement. Clinical Laboratory Standards Institute, Wayne:PA,2013.CLSI document  p. M100-S20.

12. Leonov Y, Schlaeffer F, Karpuch  J, Bourvin A, Shemesh Y, Lewinson G. Ciprofloxacin  in  the  treatment  of  nosocomial  multiply  resistant  Acinetobacter  calcoaceticus  bacteremia.  Infection 1990; 18:234-236.

13. Prashanth K, Badrinath S. In vitro susceptibility pattern of Acinetobacter species to commonly used cephalosporins, quinolones, and aminoglycosides. Indian J Med Microbiol 2004; 22:97-103.

14. Pachon J, Vila J. Treatment of multiresistant Acinetobacter baumannii infections. Curr Opin Investig Drugs 2009; 10:150-156.

15. Park S, Lee KM, Yoo YS, Yoo JS, Yoo J, Kim HS, et al. Alterations of gyrA, gyrB, and parC and activity     of efflux pump in fluoroquinolone-resistant Acinetobacter baumannii. Public Health Res Perspect 2011; 2:164-170.

16. Vila J, Ruiz J, Goni P, Marcos A, Jimenez de Anta T.  Mutation in the gyrA gene of quinolone-resistant clinical isolates of Acinetobacter baumannii. Antimicrob Agents Chemother  1995; 39:1201-1203.

17. Ardebili A,  Rastegar Lari  A, Talebi M. Correlation  of  ciprofloxacin  resistance  with  the  AdeABC efflux system in Acinetobacter baumannii clinical isolates. Ann Lab Med 2014; 34:433-438.