Center of Pharmaceutical Studies, University of Coimbra, Coimbra, Portugal.
J Water Health. 2012 Jun;10(2):288-94. doi: 10.2166/wh.2012.153.
This work aimed to investigate the association of the carriage of plasmid-mediated quinolone resistance (PMQR) genes, the virulence potential encoded in pathogenicity islands (PAIs) and the phylogenetic background in Escherichia coli strains isolated from waters of diverse origin. Antimicrobial susceptibilities were determined by the disc diffusion method. Screening for PMQR (qnr, aac(6')-Ib-variant and qepA) genes, PAIs and the determination of phylogroup was performed by PCR. Nineteen percent of strains were resistant to nalidixic acid, 11% to ciprofloxacin and 5% to gentamicin. qnrA was the only PMQR detected in 16% of strains, susceptible to quinolones and grouped in phylogenetic lineage B1. Sixty-seven percent of the isolates were assigned to the less-virulent groups A and B1. PAIs IV(536) and II(CFT073) were detected in 16 and 3% of the isolates, respectively. All PAIs were detected in the phylogroups D and B1. The presence of PAIs in isolates from waters may represent an increased risk for public health, as they were isolated from samples collected from surface and drinking waters. As E. coli is an important indicator of microbiological water quality, and also a potential pathogen, routine analysis for its detection could be complemented by screening for virulence factors and antimicrobial genes.
本研究旨在探讨质粒介导的喹诺酮类耐药（PMQR）基因、毒力岛（PAIs）编码的毒力潜力以及分离自不同来源水源的大肠杆菌菌株的系统发育背景之间的关联。采用纸片扩散法测定抗菌药物敏感性。通过 PCR 筛选 PMQR（qnr、aac(6')-Ib-variant 和 qepA）基因、PAIs 和确定系统发育群。19%的菌株对萘啶酸耐药，11%对环丙沙星耐药，5%对庆大霉素耐药。qnrA 是唯一在 16%的菌株中检测到的 PMQR，对喹诺酮类药物敏感，归属于系统发育谱系 B1。67%的分离株被归为毒力较弱的 A 组和 B1 组。IV(536)和 II(CFT073)型 PAIs 分别在 16%和 3%的分离株中检出。所有 PAIs 均在 D 组和 B1 组的分离株中检出。水源中分离出的携带 PAIs 的菌株可能对公共健康构成更大的风险，因为它们是从地表水和饮用水样本中分离出来的。由于大肠杆菌是水质微生物学的重要指示菌，也是一种潜在的病原体，因此在常规检测的基础上，增加对其毒力因子和抗生素耐药基因的筛选，可能有助于提高检测的准确性。
