Distribution of Plasmid-Mediated Quinolone Resistance, Integrons and AdeABC Efflux Pump Genes in Nosocomial Isolates of Acinetobacter baumannii

Abstract

Background: Acinetobacter baumannii is an opportunistic pathogen associated with nosocomial infections. Extensive use of quinolones has resulted in an increase of resistance in this organism worldwide. Aim and Objectives: To study the association between PMQR genes, integron carriage as well as the possible role of AdeABC efflux pump in ciprofloxacin resistance as well as multidrug resistance in clinical isolates of A. baumannii. We studied the presence of Plasmid-Mediated-Quinolone Resistance (PMQR); AdeABC efflux pump genes and integron carriage in Intensive Care Unit (ICU) isolates of A. baumannii. Material and Methods: Fifty six non-duplicate clinical isolates of A. baumannii were obtained from two hospital ICUs in Tehran from March 5th 2014 to July 20th 2015. Susceptibility to 10 antibiotics was determined by disc diffusion. Presence of PMQR (aac(6')-Ib-cr, qnrA, qnrB, qnrC, qnrD and qnrS), adeABC efflux and class I and II integron genes were detected by Polymerase Chain Reaction (PCR). Results: All isolates were Multidrug-Resistant (MDR) among which, qnrB and aac(6')-Ib-cr were detected in 7.1% and 26.8% of the isolates, respectively. However, qnrA, qnrC, qnrD and qnrS were not observed. Presence of adeA and adeB was observed in 100% and adeC in 73.2% of the isolates. Overall, integron carriage was observed in (94.6%) of the isolates including qnrB positive and 73.3% of the aac(6')-Ib-cr carrying isolates. Conclusion: Our results show that quinolone resistance is not associated with PMQR genes. On the other hand, the AdeABC efflux pump is clearly responsible for MDR in our A. baumannii isolates including resistance to quinolones. No association was found between PMQR and integron carriage.

Keywords

• Acinetobacter baumannii
• Quinolone
• Nosocomial Infections
• Integron