Advanced Drug Delivery Group, Faculty of Medicine and Health, Sydney Pharmacy School, The University of Sydney, Sydney, New South Wales, Australia.
Phage Consulting, Sydney, New South Wales, Australia.
Clin Microbiol Infect. 2022 Jul;28(7):983-989. doi: 10.1016/j.cmi.2022.01.006. Epub 2022 Feb 3.
Inhaled phage therapy has been revisited as a potential treatment option for respiratory infections caused by multidrug-resistant Pseudomonas aeruginosa; however, there is a distinct gap in understanding the dose-response effect. The aim of this study was to investigate the dose-response effect of Pseudomonas-targeting phage PEV31 delivered by the pulmonary route in a mouse lung infection model.
Neutropenic BALB/c mice were infected with multidrug-resistant P. aeruginosa (2 × 10 colony-forming units) through the intratracheal route and then treated with PEV31 at three different doses of 7.5 × 10 (Group A), 5 × 10 (Group B), and 5 × 10 (Group C) plaque-forming units, or phosphate-buffered saline at 2 hours postinoculation. Mice (n = 5-7) were euthanized at 2 hours and 24 hours postinfection, and lungs, kidneys, spleen, liver, bronchoalveolar lavage fluid, and blood were collected for bacteria and phage enumeration.
At 24 hours postinfection, all phage-treated groups exhibited a significant reduction in pulmonary bacterial load by 1.3-1.9 log, independent of the delivered phage dose. The extent of phage replication was negatively correlated with the dose administered, with log titre increases of 6.2, 2.7, and 9 for Groups A, B, and C, respectively. Phage-resistant bacterial subpopulations in the lung homogenate samples harvested at 24 hours postinfection increased with the treatment dose (i.e. 30%, 74%, and 91% in respective Groups A-C). However, the mutants showed increased susceptibility to ciprofloxacin, impaired twitching motility, and reduced blue-green pigment production. The expression of the inflammatory cytokines (IL-1ß and IL-6, and TNF-α) was suppressed with increasing PEV31 treatment dose.
This study provides the dose-response effect of inhaled phage therapy that may guide dose selection for treating P. aeruginosa respiratory infections in humans.
吸入噬菌体疗法作为治疗多重耐药铜绿假单胞菌引起的呼吸道感染的潜在治疗选择已重新受到关注；然而，人们对剂量反应效应的理解存在明显差距。本研究旨在调查肺部途径给予靶向铜绿假单胞菌噬菌体 PEV31 在小鼠肺部感染模型中的剂量反应效应。
通过气管内途径将中性粒细胞减少的 BALB/c 小鼠感染多重耐药铜绿假单胞菌（2×10 个菌落形成单位），然后在接种后 2 小时用 PEV31 以 7.5×10（A 组）、5×10（B 组）和 5×10（C 组）噬菌斑形成单位的三种不同剂量或磷酸盐缓冲盐水进行治疗。在感染后 2 小时和 24 小时处死小鼠（n=5-7），收集肺、肾、脾、肝、支气管肺泡灌洗液和血液进行细菌和噬菌体计数。
在感染后 24 小时，所有噬菌体治疗组的肺部细菌负荷均显著降低 1.3-1.9 log，与所给予的噬菌体剂量无关。噬菌体复制的程度与给药剂量呈负相关，A、B 和 C 组的对数滴度分别增加 6.2、2.7 和 9。在感染后 24 小时收获的肺匀浆样本中，噬菌体耐药细菌亚群随着治疗剂量的增加而增加（分别为 A-C 组的 30%、74%和 91%）。然而，突变体对环丙沙星的敏感性增加，扭动运动受损，蓝绿色色素产生减少。随着 PEV31 治疗剂量的增加，炎症细胞因子（IL-1ß、IL-6 和 TNF-α）的表达受到抑制。
本研究提供了吸入噬菌体治疗的剂量反应效应，可能指导治疗铜绿假单胞菌呼吸道感染的剂量选择。
