Molapour Azam, Peymani Amir, Saffarain Parvaneh, Habibollah-Pourzereshki Narges, Rashvand Pooya
Department of Microbiology, Science and Research Branch, Islamic Azad University, Tehran, Iran.
Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran.
Infect Disord Drug Targets. 2020;20(1):49-55. doi: 10.2174/1871526519666190206205521.
Plasmid-induced quinolone resistance has raised a great concern in the treatment of serious infections worldwide. The aims of this study were to determine the antibiotic susceptibility, the frequency of qepA, aac(6')-Ib and qnr genes by PCR and sequencing, and typing of the resistant isolates using repetitive extragenic palindromic sequence-based PCR (REPPCR) in Pseudomonas aeruginosa isolated from burn wound infections.
In the current cross-sectional study, 149 P. aeruginosa were isolated from the burn wound samples of patients admitted to Motahari hospital in Tehran, Iran, from February to December 2016. The bacterial isolates were identified using standard laboratory methods and their antibiotic susceptibility to quinolones was evaluated using the standard Kirby-Bauer method, according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The presence of aac(6')-Ib, qepA, qnrA, qnrB4, qnrB and qnrS genes was assessed using PCR and sequencing methods and clonal relationship of the resistant isolates was evaluated using REP-PCR method.
All (100%) isolates showed complete resistance to used quinolone compounds in this study. The qnr and qepA genes were not found, but all (100%) isolates were positive for the presence of aac(6')-Ib gene and the sequencing revealed that all (100%) belong to the aac(6')-Ib-cr variant. REP-PCR showed that the studied isolates belonged to three distinct clones of A (77.9%), B (18.1%), and C (4%).
The findings of the present study indicated the presence of aac(6')-Ib-cr variant and lack of the contribution of qnr and qepA in the emergence of resistance to quinolones in P. aeruginosa isolated from burn patients. Considering the importance of clonal spread of these resistant isolates and their significant role in the development of clinical infections, especially in patients with burns, more attention should be paid to the prevention of the dissemination of these resistant isolates.
质粒介导的喹诺酮耐药性在全球严重感染的治疗中引起了极大关注。本研究的目的是确定从烧伤创面感染分离的铜绿假单胞菌的抗生素敏感性，通过聚合酶链反应（PCR）和测序确定qepA、aac(6')-Ib和qnr基因的频率，并使用基于重复外显子回文序列的PCR（REP-PCR）对耐药菌株进行分型。
在本次横断面研究中，于2016年2月至12月从伊朗德黑兰莫塔哈里医院收治患者的烧伤创面样本中分离出149株铜绿假单胞菌。使用标准实验室方法鉴定细菌分离株，并根据临床和实验室标准协会（CLSI）指南，采用标准 Kirby-Bauer 方法评估其对喹诺酮类药物的抗生素敏感性。使用PCR和测序方法评估aac(6')-Ib、qepA、qnrA、qnrB4、qnrB和qnrS基因的存在情况，并使用REP-PCR方法评估耐药菌株的克隆关系。
本研究中所有（100%）分离株对所用喹诺酮类化合物均表现出完全耐药。未发现qnr和qepA基因，但所有（100%）分离株的aac(6')-Ib基因均呈阳性，测序显示所有（100%）均属于aac(6')-Ib-cr变体。REP-PCR表明，所研究的分离株属于三个不同的克隆，分别为A（77.9%）、B（18.1%）和C（4%）。
本研究结果表明，从烧伤患者分离的铜绿假单胞菌中存在aac(6')-Ib-cr变体，且qnr和qepA在喹诺酮耐药性的产生中不起作用。考虑到这些耐药菌株克隆传播的重要性及其在临床感染发展中的重要作用，尤其是在烧伤患者中，应更加重视预防这些耐药菌株的传播。
