Sun Xu, Pu Bingchun, Qin Jinhong, Xiang Jun
Department of Burn, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
Pathogens. 2023 Nov 28;12(12):1396. doi: 10.3390/pathogens12121396.
Infections caused by (CRKP) are becoming increasingly common within clinical settings, requiring the development of alternative therapies. In this study, we isolated, characterized, and sequenced the genome of a CRKP phage, Phage168. The total genomic DNA of Phage168 was 40,222 bp in length, encoding 49 predicted proteins. Among these proteins, Dep40, the gene product of ORF40, is a putative tail fiber protein that exhibits depolymerase activity based on the result of bioinformatics analyses. In vitro, we confirmed that the molecular weight of the Phage168 depolymerase protein was about 110 kDa, the concentration of the produced phage 168 depolymerase protein was quantified as being 1.2 mg/mL, and the depolymerase activity was still detectable after the dilution of 1.2 µg/mL. This recombinant depolymerase exhibited enzyme activity during the depolymerization of the formed CRKP biofilms. We also found that depolymerase, when combined with polymyxin B, was able to enhance the bactericidal effect of polymyxin B on CRKP strains by disrupting their biofilm. When recombinant depolymerase was used in combination with human serum, it enhanced the sensitivity of the CRKP strain UA168 to human serum, and the synergistic bactericidal effect reached the strongest level when the ratio of depolymerase to human serum was 3:1. Our results indicated that depolymerase encoded by Phage168 may be a promising strategy for combating infections caused by drug-resistant CRKP formed within the biofilm.
耐碳青霉烯类肺炎克雷伯菌（CRKP）引起的感染在临床环境中越来越普遍，需要开发替代疗法。在本研究中，我们分离、鉴定并测序了一株CRKP噬菌体Phage168的基因组。Phage168的基因组DNA全长40222 bp，编码49个预测蛋白。在这些蛋白中，ORF40的基因产物Dep40是一种假定的尾丝蛋白，基于生物信息学分析结果显示其具有解聚酶活性。在体外，我们证实Phage168解聚酶蛋白的分子量约为110 kDa，所产生的噬菌体168解聚酶蛋白浓度经定量为1.2 mg/mL，在稀释至1.2 μg/mL后仍可检测到解聚酶活性。这种重组解聚酶在形成的CRKP生物膜解聚过程中表现出酶活性。我们还发现，解聚酶与多粘菌素B联合使用时，能够通过破坏CRKP菌株的生物膜来增强多粘菌素B对其的杀菌效果。当重组解聚酶与人类血清联合使用时，它增强了CRKP菌株UA168对人类血清的敏感性，并且当解聚酶与人类血清的比例为3:1时，协同杀菌效果达到最强水平。我们的结果表明，Phage168编码的解聚酶可能是对抗生物膜内形成的耐药CRKP引起的感染的一种有前景的策略。
