School of Pharmaceutical Sciences of Ribeirão Preto, São Paulo University (USP), Ribeirão Preto, SP 14040-903, Brazil.
School of Agricultural and Veterinary Sciences, São Paulo State University (UNESP), Jaboticabal, SP 14884-900, Brazil.
Infect Genet Evol. 2018 Jun;60:66-70. doi: 10.1016/j.meegid.2018.02.003. Epub 2018 Feb 7.
The expression of plasmid-mediated quinolone resistance (PMQR) genes confers low-level quinolone and fluoroquinolones resistance alone. However, the association to chromosomal resistance mechanisms determines an expressively higher resistance in Enterobacteriaceae. These mechanisms are horizontally disseminated within plasmids and have contributed to the emergence of bacteria with reduced susceptibility or resistant to therapies worldwide. The epidemiological characterization of PMQR dissemination is highly relevant in the scientific and medical context, to investigate the dissemination within enterobacteria, from different populations, including humans and food-producing animals. In the present study, 200 Enterobacteriaceae isolates were harvested from poultry with cloacal swabs and identified as Escherichia coli (90.5%), Escherichia fergusonii (5.5%), Klebsiella oxytoca (2.5%) and Klebsiella pneumoniae (1.5%). Among isolates evaluated, 46 (23%) harboured PMQR genes including qnrB (43/200), qnrS (2/200) and aac(6')-Ib-cr (1/200). All isolates carrying PMQR genes showed multidrug-resistance phenotype. The 36 E. coli isolates showed 18 different PFGE types. All E. fergusonii isolates showed the same PFGE type. The two Klebsiella oxytoca belonged to two different PFGE types. The phylogenetic groups A, B1, and D were found among the E. coli harboring PMQR genes. Based on the phylogenetic analysis and PFGE, the population structure of E. coli isolates was diverse, even within the same farm. All isolates carrying qnrB and qnrS genes also harboured ColE-like plasmids. The Southern blot hybridization using the S1-PFGE revealed that the qnrB genes were located on low molecular weight plasmids, smaller than 10Kb. Resistance plasmids were sequenced and showed 100% identity with plasmid pPAB19-3. The association of PMQR genes with mobile genetic elements, such as transferable plasmids, favours the selection and dissemination of (fluoro) quinolones resistant bacteria among food-producing animals, and may play an important role in the current increased prevalence of resistant bacteria in different environments reported worldwide.
质粒介导的喹诺酮类耐药（PMQR）基因的表达单独赋予了低水平的喹诺酮类和氟喹诺酮类耐药性。然而，与染色体耐药机制的关联决定了肠杆菌科的耐药性显著增加。这些机制在质粒中水平传播，并导致了全球范围内对治疗药物敏感性降低或耐药的细菌的出现。PMQR 传播的流行病学特征在科学和医学领域非常重要，可用于研究不同人群（包括人类和食用动物）中肠杆菌内的传播。在本研究中，从禽类的泄殖腔拭子中采集了 200 株肠杆菌，并鉴定为大肠杆菌（90.5%）、弗格森埃希氏菌（5.5%）、产酸克雷伯菌（2.5%）和肺炎克雷伯菌（1.5%）。在所评估的分离株中，有 46 株（23%）携带 PMQR 基因，包括 qnrB（43/200）、qnrS（2/200）和 aac(6')-Ib-cr（1/200）。所有携带 PMQR 基因的分离株均表现出多药耐药表型。36 株大肠杆菌分离株显示 18 种不同的 PFGE 型。所有弗格森埃希氏菌分离株显示相同的 PFGE 型。两种产酸克雷伯菌属于两种不同的 PFGE 型。携带 PMQR 基因的大肠杆菌中存在 A、B1 和 D 组进化群。基于系统发育分析和 PFGE，大肠杆菌分离株的种群结构多样，即使在同一农场内也是如此。携带 qnrB 和 qnrS 基因的所有分离株还携带 ColE 样质粒。使用 S1-PFGE 的 Southern blot 杂交显示，qnrB 基因位于小于 10Kb 的低分子量质粒上。抗性质粒测序显示与质粒 pPAB19-3 完全一致。PMQR 基因与移动遗传元件（如可转移质粒）的关联，有利于（氟）喹诺酮类耐药菌在食用动物中的选择和传播，并可能在当前全球不同环境中报告的耐药菌流行率增加方面发挥重要作用。
