Service de Bactériologie et Hygiène, Centre Hospitalier Régional Universitaire Tours, France ; UMR 1282, Infectiologie et Santé Publique, Université Francois Rabelais Tours, France.
Genomic Research Laboratory, University of Geneva Hospitals Geneva, Switzerland.
Front Microbiol. 2014 Dec 5;5:652. doi: 10.3389/fmicb.2014.00652. eCollection 2014.
Until recently, Staphylococcus aureus from clonal complex (CC)398 were mostly described as colonizing asymptomatic raised pigs and pig-farmers. Currently, the epidemiology of the CC398 lineage is becoming more complex. CC398 human-adapted isolates are increasingly being identified in bloodstream infections in humans living in animal-free environments. In addition, CC398 isolates are increasingly responsible for invasive infections in various animals. CC398 isolates that colonize asymptomatic pigs and the isolates that infect humans living in animal-free environments (human-adapted isolates) both lack several clinically important S. aureus-associated virulence factors but differ on the basis of their prophage content. Recent findings have provided insight into the influence of a φMR11-like helper prophage on the ability of CC398 isolates to infect humans. To assess the recent spread of the CC398 lineage to various animal species and to investigate the links between the φMR11-like prophage and the emergence of CC398 isolates infecting animals, we studied 277 isolates causing infections in unrelated animals. The prevalence of CC398 isolates increased significantly between 2007 and 2013 (p < 0.001); 31.8% of the animal isolates harbored the φMR11-like prophage. High-density DNA microarray experiments with 37 representative infected-animal isolates positive for φMR11-like DNA established that most infected-animal isolates carried many genetic elements related to antimicrobial resistance and virulence genes, and a φ3 prophage encoding immune-modulating proteins and associated with animal-to-human jumps. Our findings suggest recent clonal expansion and dissemination of a new subpopulation of CC398 isolates, responsible for invasive infections in various animals, with a considerable potential to colonize and infect humans, probably greater than that of human-adapted CC398 isolates, justifying active surveillance.
直到最近，来自克隆复合体 (CC)398 的金黄色葡萄球菌大多被描述为定植于无症状的凸起猪和养猪户。目前，CC398 谱系的流行病学变得更加复杂。越来越多的在无动物环境中生活的人类血流感染中发现了适应人类的 CC398 分离株。此外，CC398 分离株越来越多地导致各种动物的侵袭性感染。定植于无症状猪的 CC398 分离株和感染无动物环境中人类的分离株（适应人类的分离株）均缺乏几种与临床相关的金黄色葡萄球菌相关毒力因子，但在其噬菌体含量的基础上有所不同。最近的研究结果提供了对 φMR11 样辅助噬菌体影响 CC398 分离株感染人类能力的深入了解。为了评估 CC398 谱系最近在各种动物物种中的传播，并调查 φMR11 样噬菌体与感染动物的 CC398 分离株出现之间的联系，我们研究了 277 株引起无关动物感染的分离株。2007 年至 2013 年期间，CC398 分离株的流行率显著增加（p<0.001）；31.8%的动物分离株携带 φMR11 样噬菌体。对 37 株携带 φMR11 样 DNA 的代表性感染动物分离株进行高密度 DNA 微阵列实验表明，大多数感染动物分离株携带许多与抗菌药物耐药性和毒力基因相关的遗传元件，以及编码免疫调节蛋白的 φ3 噬菌体，并与动物到人类的跳跃有关。我们的研究结果表明，最近 CC398 分离株的新亚群发生了克隆扩张和传播，导致各种动物的侵袭性感染，具有定植和感染人类的相当大的潜力，可能大于适应人类的 CC398 分离株，因此需要积极监测。
