Hyperbaric Oxygen Reduces Aspergillus fumigatus Proliferation In Vitro and
Influences In Vivo Disease Outcomes
Souabh Dhingra, Jay C Buckey, Robert A Cramer Published: March 2018
ABSTRACT: Recent estimates suggest that more than 3 million people have chronic or invasive fungal infections, causing more than 600,000deaths every year.
Aspergillus fumigatus causes invasive pulmonary aspergillosis (IPA) in patients with compromised immune systems and is a primary contributor to increases in human fungal infections. Thus,the development of new clinical modalities as stand-alone or adjunctive therapy for improving IPA patient outcomes is critically needed.
Here we tested the in vitro and in vivo impacts of hyperbaric oxygen (HBO)(100% oxygen,>1atmosphere absolute [ATA]) on A.fumiga-tus proliferation and murine IPA outcomes.
Our findings indicate that HBO reduces established fungal biofilm proliferation in vitro by over 50%.
The effect of HBO under the treatment conditions was transient and fungistatic,with A. fumiga-tus metabolic actvity rebounding within 6 h of HBO treatment being removed.
In vivo,daily HBO provides a dose-dependent but modest improvement in murine IPA disease outcomes as measured by survival analysis.Intriguingly,no synergy was observed between subtherapeutic voriconazole or amphotericin B and HBO in vitro or in vivo with daily HBO dos-ing,though the loss of fungal superoxide dis-mutase genes enhanced HBO antifungal activity.Further studies are needed to optimize the HBO treatment regimen and better understand the effects of HBO on both the host and the pathogen during a pulmonary invasive fungal infection.