Eftekhar Fereshteh, Seyedpour Seyed Mohsen
Department of Microbiology, Faculty of Biological Sciences, Shahid Beheshti University, Tehran, Iran.
Iran J Med Sci. 2015 Nov;40(6):515-21.
Plasmid mediated quinolone resistance (PMQR) has been shown to play an important role in resistance not only to quinolones, but also β-lactams and aminoglycosides. In fact, qnr genes are frequently carried along with β-lactamase determinants on the same plasmids. We studied the prevalence of qnrA, qnrB, qnrS and aac(6')-Ib-cr genes among quinolone and cephalosporin resistant clinical isolates of Klebsiella pneumoniae (K. pneumoniae), as well as the association between PMQR genes with resistance to quinolones, cephalosporins and aminoglycosides.
The study was conducted on 79 K. pneumoniae clinical isolates collected from Imam Hussein hospital in Tehran between July 2010 and January 2011, based on their resistance to quinilones and cephalosporins. Antibacterial susceptibility was determined to 15 antibiotics by disc diffusion. Presence of qnrA, qnrB, qnrS and aac(6')-Ib-cr genes were investigated using specific primers and PCR.
Of the 79 K. pneumoniae isolates, 47 (59.5%) carried the PMQR determinants. Among these, 42 (89.4%) carried aac(6')-Ib-cr of which, 21 (50%) also harbored qnrB. Three isolates carried qnrB alone, two (4.2%) harbored qnrS and none had qnrA. Resistance to aminoglycosides and cephalosporins was significantly higher in the isolates carrying both qnrB and aac(6')-Ib-cr genes compared to aac(6')-Ib-cr alone.
This study showed a high prevalence of aac(6')-Ib-cr and qnrB genes among the Iranian K. pneumoniae clinical isolates as well as co-carriage of the two genes. There was a significant association between qnrB gene carriage and resistance to quinolones, cephalosporins, and aminoglycosides.
质粒介导的喹诺酮耐药性（PMQR）已被证明不仅在对喹诺酮类药物的耐药性中起重要作用，而且在对β-内酰胺类和氨基糖苷类药物的耐药性中也起重要作用。事实上，qnr基因经常与β-内酰胺酶决定簇存在于同一质粒上。我们研究了肺炎克雷伯菌（K. pneumoniae）对喹诺酮类和头孢菌素耐药的临床分离株中qnrA、qnrB、qnrS和aac(6')-Ib-cr基因的流行情况，以及PMQR基因与对喹诺酮类、头孢菌素类和氨基糖苷类药物耐药性之间的关联。
本研究基于对喹诺酮类和头孢菌素类药物的耐药性，对2010年7月至2011年1月期间从德黑兰伊玛目侯赛因医院收集的79株肺炎克雷伯菌临床分离株进行了研究。采用纸片扩散法测定了对15种抗生素的抗菌敏感性。使用特异性引物和PCR检测qnrA、qnrB、qnrS和aac(6')-Ib-cr基因的存在情况。
在79株肺炎克雷伯菌分离株中，47株（59.5%）携带PMQR决定簇。其中，42株（89.4%）携带aac(6')-Ib-cr，其中21株（50%）还携带qnrB。3株分离株单独携带qnrB，2株（4.2%）携带qnrS，无一株携带qnrA。与仅携带aac(6')-Ib-cr基因的分离株相比，同时携带qnrB和aac(6')-Ib-cr基因的分离株对氨基糖苷类和头孢菌素类药物的耐药性显著更高。
本研究表明，伊朗肺炎克雷伯菌临床分离株中aac(6')-Ib-cr和qnrB基因的流行率较高，且这两个基因存在共携带情况。qnrB基因携带与对喹诺酮类、头孢菌素类和氨基糖苷类药物的耐药性之间存在显著关联。
