Domokos Judit, Damjanova Ivelina, Kristof Katalin, Ligeti Balazs, Kocsis Bela, Szabo Dora
Institute of Medical Microbiology, Semmelweis University, Budapest, Hungary.
National Public Health Institute, Budapest, Hungary.
Front Microbiol. 2019 Feb 12;10:157. doi: 10.3389/fmicb.2019.00157. eCollection 2019.
International high-risk clones of are among the most common nosocomial pathogens. Increased diversity of plasmid-encoded antimicrobial resistance genes facilitates spread of these clones causing significant therapeutic difficulties. The purpose of our study was to investigate fluoroquinolone resistance in extended-spectrum beta-lactamase (ESBL)-producing strains, including four and a single , isolated from blood cultures in Hungary. Whole-genome sequencing and molecular typing including multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) were performed in selected strains. Gene expression of plasmid-mediated quinolone resistance determinants (PMQR) was investigated by quantitative-PCR. MLST revealed that three strains belonged to ST11 and one to ST307 whereas . belonged to ST52. The isolates harbored different β-lactamase genes, however, all uniformly carried . The isolates exhibited resistance to fluoroquinolones and carried various PMQR genes namely, two ST11 strains harbored , the ST307 strain harbored and all harbored efflux pump. Levofloxacin and moxifloxacin MIC values of ST11 and ST307 clones correlated with and expression levels. The carrying ST52 exhibited reduced susceptibility to fluoroquinolones. The maintained expression of genes in parallel with chromosomal mutations indicate an additional protective role of Qnr proteins that can support dissemination of high-risk clones. During development of high-level fluoroquinolone resistance, high-risk clones retain fitness thus, enabling them for dissemination in hospital environment. Based on our knowledge this is the first report of ST307 clone in Hungary, that is emerging as a potential high-risk clone worldwide. High-level fluoroquinolone resistance in parallel with upregulated PMQR gene expression are linked to high-risk clones.
国际高风险克隆株是最常见的医院病原体之一。质粒编码的抗菌耐药基因多样性增加促进了这些克隆株的传播，造成了严重的治疗困难。我们研究的目的是调查从匈牙利血培养物中分离出的产超广谱β-内酰胺酶（ESBL）菌株中的氟喹诺酮耐药性，其中包括4株肺炎克雷伯菌和1株大肠埃希菌。对选定菌株进行了全基因组测序和分子分型，包括多位点序列分型（MLST）和脉冲场凝胶电泳（PFGE）。通过定量PCR研究质粒介导的喹诺酮耐药决定簇（PMQR）的基因表达。MLST显示，3株肺炎克雷伯菌菌株属于ST11，1株属于ST307，而大肠埃希菌属于ST52。分离株携带不同的β-内酰胺酶基因，然而，所有肺炎克雷伯菌均一致携带blaCTX-M-15。肺炎克雷伯菌分离株对氟喹诺酮类药物耐药，并携带各种PMQR基因，即2株ST11菌株携带qnrS，ST307菌株携带qnrD，所有大肠埃希菌均携带qepA外排泵。ST11和ST307克隆株的左氧氟沙星和莫西沙星MIC值与qnrS和qepA表达水平相关。携带qnrB4的ST52大肠埃希菌对氟喹诺酮类药物的敏感性降低。qnr基因与染色体突变同时维持表达表明Qnr蛋白具有额外的保护作用，可支持高风险克隆株的传播。在高水平氟喹诺酮耐药性发展过程中，高风险克隆株保持适应性，从而使其能够在医院环境中传播。据我们所知，这是匈牙利首次报道ST307克隆株，该克隆株正在成为全球潜在的高风险克隆株。高水平氟喹诺酮耐药性与上调的PMQR基因表达与高风险肺炎克雷伯菌克隆株有关。
