The effects of different doses of inhaled bacteriophage therapy for Pseudomonas aeruginosa pulmonary infections in mice

Rachel Yoon Kyung Chang; Michael Y T Chow; Yuncheng Wang; Chengxi Liu; Qixuan Hong; Sandra Morales; Andrew J McLachlan; Elizabeth Kutter; Jian Li; Hak-Kim Chan

doi:10.1016/j.cmi.2022.01.006

The effects of different doses of inhaled bacteriophage therapy for Pseudomonas aeruginosa pulmonary infections in mice

Clin Microbiol Infect. 2022 Jul;28(7):983-989. doi: 10.1016/j.cmi.2022.01.006. Epub 2022 Feb 3.

Authors

Affiliations

¹ Advanced Drug Delivery Group, Faculty of Medicine and Health, Sydney Pharmacy School, The University of Sydney, Sydney, New South Wales, Australia.
² Phage Consulting, Sydney, New South Wales, Australia.
³ Faculty of Medicine and Health, Sydney Pharmacy School, The University of Sydney, Sydney, New South Wales, Australia.
⁴ The Evergreen State College, Olympia, WA, USA.
⁵ Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia; Department of Microbiology, Monash University, Clayton, Victoria, Australia.
⁶ Advanced Drug Delivery Group, Faculty of Medicine and Health, Sydney Pharmacy School, The University of Sydney, Sydney, New South Wales, Australia. Electronic address: kim.chan@sydney.edu.au.

PMID: 35123053
DOI: 10.1016/j.cmi.2022.01.006

Abstract

Objectives: 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.

Methods: Neutropenic BALB/c mice were infected with multidrug-resistant P. aeruginosa (2 × 10⁴ colony-forming units) through the intratracheal route and then treated with PEV31 at three different doses of 7.5 × 10⁴ (Group A), 5 × 10⁶ (Group B), and 5 × 10⁸ (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.

Results: At 24 hours postinfection, all phage-treated groups exhibited a significant reduction in pulmonary bacterial load by 1.3-1.9 log₁₀, independent of the delivered phage dose. The extent of phage replication was negatively correlated with the dose administered, with log₁₀ 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.

Discussion: This study provides the dose-response effect of inhaled phage therapy that may guide dose selection for treating P. aeruginosa respiratory infections in humans.

Keywords: Bacteriophage (or phage); Dose–response; Inhaled therapy; Intratracheal administration; Pseudomonas aeruginosa; Pulmonary infection.

MeSH terms

Animals
Bacteriophages*
Disease Models, Animal
Humans
Lung / microbiology
Mice
Mice, Inbred BALB C
Phage Therapy*
Pseudomonas Infections* / drug therapy
Pseudomonas aeruginosa
Respiratory Tract Infections* / therapy