Department of Life Sciences, Manchester Metropolitan University, Manchester, United Kingdom.
Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom.
Front Cell Infect Microbiol. 2021 Jul 6;11:698909. doi: 10.3389/fcimb.2021.698909. eCollection 2021.
Phage therapy recently passed a key milestone with success of the first regulated clinical trial using systemic administration. In this single-arm non-comparative safety study, phages were administered intravenously to patients with invasive infections with no adverse reactions reported. Here, we examined features of 78 lytic phages, most of which were propagated using a host modified to be broadly susceptible to staphylococcal phage infection. Use of this host eliminates the threat of contamination with staphylococcal prophage - the main vector of horizontal gene transfer. We determined the host range of these phages against an international collection of 185 isolates with 56 different multilocus sequence types that included multiple representatives of all epidemic MRSA and MSSA clonal complexes. Forty of our 78 phages were able to infect > 90% of study isolates, 15 were able to infect > 95%, and two could infect all 184 clinical isolates, but not a phage-resistant mutant generated in a previous study. We selected the 10 phages with the widest host range for characterization by planktonic culture time-kill analysis against four isolates:- modified strain TM300H, methicillin-sensitive isolates D329 and 15981, and MRSA isolate 252. Six of these 10 phages were able to rapidly kill, reducing cell numbers of at least three isolates. The four best-performing phages, in this assay, were further shown to be highly effective in reducing 48 h biofilms on polystyrene formed by eight ST22 and eight ST36 MRSA isolates. Genomes of 22 of the widest host-range phages showed they belonged to the subfamily of the order in three main groups corresponding to , and two distinct groups of . These genomes assembled as single-linear dsDNAs with an average length of 140 kb and a GC content of 30%. Phages that could infect > 96% of isolates were found in all three groups, and these have great potential as therapeutic candidates if, in future studies, they can be formulated to maximize their efficacy and eliminate emergence of phage resistance by using appropriate combinations.
噬菌体疗法最近取得了一个关键的里程碑，首次成功进行了全身性给药的监管临床试验。在这项单臂非对照安全性研究中，噬菌体被静脉内给药给患有侵袭性感染的患者，没有报告不良反应。在这里，我们检查了 78 种溶菌噬菌体的特征，其中大多数是使用一种被广泛易感于葡萄球菌噬菌体感染的宿主进行繁殖的。使用这种宿主消除了带有葡萄球菌原噬菌体的污染威胁——水平基因转移的主要载体。我们针对一个包含 185 个分离株的国际集合，使用这些噬菌体来确定它们的宿主范围，这些分离株具有 56 种不同的多位点序列类型，其中包括所有流行的 MRSA 和 MSSA 克隆复合体的多个代表。我们的 78 种噬菌体中有 40 种能够感染>90%的研究分离株，15 种能够感染>95%，两种能够感染所有 184 种临床分离株，但不能感染以前研究中产生的抗噬菌体突变体。我们选择了 10 种宿主范围最广的噬菌体进行浮游培养时间杀伤分析，针对四个分离株进行了表征：-修饰菌株 TM300H、甲氧西林敏感的分离株 D329 和 15981 以及 MRSA 分离株 252。这 10 种噬菌体中有 6 种能够快速杀死，减少至少三种分离株的细胞数量。在这项测定中，这四种表现最好的噬菌体进一步被证明能够有效减少由 8 个 ST22 和 8 个 ST36 MRSA 分离株形成的 48 小时聚苯乙烯生物膜。22 种宿主范围最广的噬菌体的基因组表明它们属于目科的亚科，分为三个主要组，对应于 、和两个不同的组。这些基因组组装为单一线性 dsDNA，平均长度为 140kb，GC 含量为 30%。能够感染>96%的分离株的噬菌体在所有三个组中都有发现，如果在未来的研究中，通过适当的组合来最大限度地提高它们的疗效并消除噬菌体耐药性的出现，那么这些噬菌体具有很大的治疗潜力。
