Peng Shih-Yi, Chen Li-Kuang, Wu Wen-Jui, Paramita Prajna, Yang Po-Wei, Li Yun-Zhong, Lai Meng-Jiun, Chang Kai-Chih
Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien, Taiwan.
Department of Biochemistry, Tzu Chi University, Hualien, Taiwan.
Front Microbiol. 2020 May 13;11:728. doi: 10.3389/fmicb.2020.00728. eCollection 2020.
spp. are a group of non-fermentative, Gram-negative, catalase-positive, and non-motile bacilli. They can cause meningitis in neonates and immunosuppressed patients, and lead to high mortality. Considering the rising trend of drug resistance among bacteria pathogens, bacteriophage (phage) therapy is a potential alternative to antibiotics for treating multidrug-resistant bacterial infections. However, so far, no phages specific for spp. have been reported. Using a clinically isolated as the host, the phage TCUEAP1 was isolated from wastewater of Hualien Tzu Chi hospital. The phage particle of TCUEAP1 under electron microscopy was revealed to belong to the siphoviridae family, with a head size of 47 nm, and a tail dimension 12 nm in diameter and 172 nm in length. The one-step growth analysis showed that the latent period of TCUEAP1 was about 40 min with a rise period lasting about 20 min, yielding a burst size of approximately 10 PFU/cell. The adsorption rate of TCUEAP1 reached about 70% in 20 min. Using 20 isolates of spp. to test the host range of TCUEAP1, it displayed narrow spectrum infecting three strains of , but forming spot lysis on 16 strains. The sequence result showed that the genome of TCUEAP1 is a double-stranded DNA of 49,816 bp, containing 73 predicted open reading frames. Further genomic analysis showed TCUEAP1 to be a new phage with no resemblance to publicly available phage genomes. Finally, in a mouse intraperitoneal infection model, at 6 h after the bacterial injection, TCUEAP1 decreased the bacterial load by fivefold in blood. Also, TCUEAP1 rescued 80% of mice heavily infected with from lethal bacteremia. We hope that the isolation and characterization of TCUEAP1, the first phage infecting spp., can promote more studies of the phages targeting this newly emerging bacterial pathogen.
某菌属是一组非发酵、革兰氏阴性、过氧化氢酶阳性且无运动性的杆菌。它们可导致新生儿和免疫抑制患者发生脑膜炎，并导致高死亡率。鉴于细菌病原体耐药性的上升趋势，噬菌体疗法是治疗多重耐药细菌感染的一种潜在抗生素替代方法。然而，到目前为止，尚未报道有针对某菌属的特异性噬菌体。以临床分离的某菌作为宿主，从花莲慈济医院的废水中分离出噬菌体TCUEAP1。电子显微镜下显示TCUEAP1的噬菌体颗粒属于长尾噬菌体科，头部大小为47纳米，尾部直径12纳米，长度172纳米。一步生长分析表明，TCUEAP1的潜伏期约为40分钟，上升期持续约20分钟，裂解量约为每细胞10个噬菌斑形成单位。TCUEAP1在20分钟内的吸附率达到约70%。用20株某菌属菌株测试TCUEAP1的宿主范围，它显示出窄谱感染三株某菌，但对16株菌株形成斑点裂解。序列结果表明，TCUEAP1的基因组是一个49,816碱基对的双链DNA，包含73个预测的开放阅读框。进一步的基因组分析表明，TCUEAP1是一种新型噬菌体，与公开可用的噬菌体基因组没有相似之处。最后，在小鼠腹腔感染模型中，在注射细菌后6小时，TCUEAP1使血液中的细菌载量降低了五倍。此外，TCUEAP1挽救了80%严重感染某菌的小鼠免于致死性菌血症。我们希望，首例感染某菌属的噬菌体TCUEAP1的分离和特性鉴定能够促进针对这种新出现的细菌病原体的噬菌体的更多研究。
