Department of Microbiology and Immunology, Faculty of Pharmacy, Ahram Canadian University, Giza, Egypt.
Microbiology and Immunology Department, Faculty of Pharmacy, Ain Shams University, African Union Organization St, Abbassia, 11566, Cairo, Egypt.
Ann Clin Microbiol Antimicrob. 2024 Feb 15;23(1):17. doi: 10.1186/s12941-024-00678-3.
Salmonella infections continue to be one of the essential public health issues threatening millions of people. With the increasing occurrence of resistance against conventionally used antibiotics, the search for alternatives has become crucial. In this study, we aimed to isolate, characterize, and evaluate two lytic bacteriophages against clinically isolated multidrug-resistant (MDR) Salmonella serovars.
Screening for the phage lytic activity was performed using a spot test. Characterization of the isolated phages was done by determining the host range, longevity test, and the effect of temperature, pH, organic solvents, and morphological characterization using a transmission electron microscope. Genomic analysis was performed using Oxford nanopore sequencing. The lytic activities of the free phage lysates and formulated phage as microencapsulated were evaluated both in vitro and in vivo.
Two phages (VB_ST_E15 and VB_ST_SPNIS2) were successfully isolated and showed lytic strong activities against MDR Salmonella (S.) Typhimurium ATCC 14,028, S. Paratyphi A, and S. Typhi. The two phages survived at the tested temperatures, maintained their infectivity for 90 days, and retained their activity until 60 °C with thermal inactivation at 65 °C. They were lytic at a pH range from 3 to 11 but lost their activities at extremely acidic or alkaline pH. The phages could withstand the organic solvents but were completely inactivated by 100% ethanol. Both phages were classified under the order Caudoviricetes, and Genus: Uetakevirus. Their genomic sequences were assembled, annotated, and submitted to the NCBI GenBank database (OR757455 and OR757456). The preclinical evaluation using the murine animal model revealed that the two-phage cocktail managed MDR Salmonella infection as evidenced by the reduction in the bacterial burden, increased animal weight, and histopathological examination.
The two encapsulated phage formulas could be considered promising candidates for the management of MDR Salmonella-associated infections and clinical analysis should be undertaken to evaluate their potential use in humans.
沙门氏菌感染仍是威胁数百万人的重要公共卫生问题之一。由于传统抗生素耐药性的不断增加，寻找替代品变得至关重要。在这项研究中，我们旨在分离、鉴定和评估两种针对临床分离的多药耐药（MDR）沙门氏菌血清型的溶菌噬菌体。
使用点测试筛选噬菌体的溶菌活性。通过确定宿主范围、寿命测试以及温度、pH 值、有机溶剂和透射电子显微镜下的形态特征来对分离的噬菌体进行特征描述。使用牛津纳米孔测序进行基因组分析。评估游离噬菌体裂解物和微囊化制剂噬菌体的裂解活性，分别在体外和体内进行。
成功分离出两种噬菌体（VB_ST_E15 和 VB_ST_SPNIS2），它们对 MDR 沙门氏菌（鼠伤寒沙门氏菌 ATCC 14,028、副伤寒 A 沙门氏菌和伤寒沙门氏菌）具有强烈的溶菌活性。两种噬菌体在测试温度下存活，在 90 天内保持感染性，并在 60°C 下保持活性，65°C 时热失活。它们在 pH 值 3 到 11 的范围内具有溶菌活性，但在极酸性或碱性 pH 值下失去活性。噬菌体能耐受有机溶剂，但 100%乙醇可完全使噬菌体失活。两种噬菌体均属于长尾病毒目，属 Uetakevirus。它们的基因组序列被组装、注释，并提交给 NCBI GenBank 数据库（OR757455 和 OR757456）。使用小鼠动物模型进行的临床前评估表明，两种噬菌体鸡尾酒可控制 MDR 沙门氏菌感染，表现为细菌负荷减少、动物体重增加和组织病理学检查。
两种封装噬菌体配方可被视为治疗 MDR 沙门氏菌相关感染的有前途的候选药物，应进行临床分析以评估其在人类中的潜在用途。
