Quinolone resistance associated with efllux pumps mexAB-oprM in clinical isolates of Pseudomonas aeruginosa

Subject Areas : Medical Microbiology

Mitra  Salehi ¹ (Assistant Professor, Department of Microbiology, Faculty of Bioscience, Islamic Azad University, North Tehran Branch, Tehran, Iran.)
Mina  Hekmatdoost ² (MS.c., Department of Microbiology, Faculty of Bioscience, Islamic Azad University, North Tehran Branch, Tehran, Iran.)
Farzaneh  Hosseini ³ (Assistant Professor, Department of Microbiology, Faculty of Bioscience, Islamic Azad University, North Tehran Branch, Tehran, Iran.)

Received: 2013-10-07 Accepted : 2013-12-13 Published : 2014-03-01

Keywords: Pseudomonas aeruginosa, mexB, Quinolone resistance, Multidrug efllux pumps,

Abstract :

Background and Objectives: Pseudomonas aeruginosa is one of the most common antibiotic resistant bacteria and, therefore, treatments of Pseudomonad-caused infections are complicated. MexAB-OprM pump exports many antimicrobial compounds regardless of their structural and functional similarities. The mexB gene encodes a proton-drug antiporter in MexAB-OprM pump. The present study was aimed to evaluate and detect the quinolone resistance associated with efllux pumps mexAB-oprM in P. aeruginosa isolated from clinical specimens. Materials and Methods: This cross-sectional study was performed on 104 P. aeruginosa isolated from patients hospitalized in Trauma and Burn Intensive Care Unit (TBICU). The Genera and strains were identified primarily based on biochemical tests. The evaluation of antibiotic resistance pattern was carried out using disk diffusion method for 11 common antibiotics and microdilution broth method for 4 antibiotics. The presence of mexB gene was investigated using PCR method. Results: According to the results, the most antibiotic resistance pattern were seen through treatment with nalidixic acid (86.54%), ceftazidime (82.2%) and ofloxacin (81.78%). Furthermore, the minimum antibiotic resistance were observed through treatment with imipenem (40.91%), piperacillin (44.9%) and tetracycline (48.03%). Based on MIC, the highest and lowest antibiotic sensitivity was recorded for tetracycline and ceftriaxone, respectively. Based on the PCR method, 27% of the clinical isolates harbor the mexAB-oprM operon. Conclusion: Based on the results, there is a significant association between presence of mexB gene and mexAB-oprM pump and antibiotic resistance in P. aeruginosa. Regarding the importance of antibiotic resistance, the study of other efllux pumps, comparison of antibiotic resistance profile and the relationship between efllux pumps and clinical origin of the strains are recommended.