Gdansk University of Technology, ul, G, Narutowicza 11/12, Gdansk 80-952, Poland.
BMC Microbiol. 2014 Mar 14;14:66. doi: 10.1186/1471-2180-14-66.
Enterococci, ubiquitous colonizers of humans and other animals, play an increasingly important role in health-care associated infections (HAIs). It is believed that the recent evolution of two clinically relevant species, Enterococcus faecalis and Enterococcus faecium occurred in a big part in a hospital environment, leading to formation of high-risk enterococcal clonal complexes (HiRECCs), which combine multidrug resistance with increased pathogenicity and epidemicity. The aim of this study was to establish the species composition in wastewater, its marine recipient as well as a river estuary and to investigate the antimicrobial susceptibility of collected isolates. Molecular methods were additionally applied to test the presence of HiRRECC-related E. faecium.
Two wastewater treatment plants (WWTPs), their marine outfalls and Vistula river that influence significantly the quality of waters in Gulf of Gdansk were sampled to investigate the presence of Enterococcus spp. Four-hundred-twenty-eight isolates were obtained, including E. faecium (244 isolates, 57.0%), E. hirae (113 isolates, 26.4%) and E. faecalis (63 isolates, 14.7%); other species (E. gallinarum/casseliflavus, E. durans and E. avium) accounted for 1.9%. Antimicrobial susceptibility testing revealed the presence of isolates resistant to erythromycin, tetracycline, amipicillin, fluoroquinolones and aminoglycosides (high-level resistance), especially among E. faecium, where such isolates were usually characterized by multilocus sequence types associated with nosocomial lineages 17, 18 and 78 of this species representing HiRECC, formerly called CC17. These isolates not only carried several resistance determinants but were also enriched in genes encoding pathogenicity factors (Esp, pili) and genes associated with mobile genetic elements (MGE), a feature also typical for nosocomial HiRECC.
Our data show that WWTPs constitute an important source of enterococcal strains carrying antimicrobial resistance determinants, often associated with the presence of MGE, for the recipient water environment, thus increasing a pool of such genes for other organisms. The presence of HiRECCs in wastewaters and marine/river environment may indicate that adaptations gained in hospitals may be also beneficial for survival of such clones in other settings. There is an obvious need to monitor the release and spread of such strains in order to elucidate better ways to curb their dissemination.
肠球菌是人类和其他动物的普遍定植者，在与医疗保健相关的感染（HAIs）中发挥着越来越重要的作用。据信，两种临床相关的物种，粪肠球菌和屎肠球菌，最近的进化很大程度上发生在医院环境中，导致形成高风险肠球菌克隆复合体（HiRECCs），这些复合体结合了多种药物耐药性和增加的致病性和流行性。本研究的目的是确定废水中的物种组成、其海洋接收体以及河流入海口，并研究收集的分离物的抗菌药敏性。此外，还应用分子方法检测 HiRRECC 相关屎肠球菌的存在。
对两个污水处理厂（WWTP）、其海洋排放口和影响加里宁格勒湾水质的维斯图拉河进行了采样，以调查肠球菌属的存在。共获得 428 株分离物，包括屎肠球菌（244 株，57.0%）、海氏肠球菌（113 株，26.4%）和粪肠球菌（63 株，14.7%）；其他种（鸟肠球菌/鹑鸡肠球菌、耐久肠球菌和鸡肠球菌）占 1.9%。抗菌药敏试验显示，分离物对红霉素、四环素、氨苄西林、氟喹诺酮类和氨基糖苷类药物（高水平耐药）具有耐药性，特别是屎肠球菌，其中此类分离物通常具有与该物种的医院谱系 17、18 和 78 相关的多位点序列类型，代表以前称为 CC17 的 HiRECC。这些分离物不仅携带几种耐药决定因素，而且还富含编码致病性因子（Esp、菌毛）和与移动遗传元件（MGE）相关的基因，这也是医院性 HiRECC 的一个典型特征。
我们的数据表明，污水处理厂是携带抗菌耐药决定因素的肠球菌菌株的重要来源，这些菌株通常与 MGE 的存在有关，为受纳水环境增加了此类基因的库。HiRECC 在废水和海洋/河流环境中的存在表明，在医院获得的适应可能也有利于此类克隆在其他环境中的生存。显然需要监测此类菌株的释放和传播，以更好地阐明遏制其传播的方法。
