A new study reveals that oxygen support may cause harm to the lung due to its microbiome. A study from Michigan Medicine, University of Medicine, was recently published in the journal Science Translational Medicine describing how the shortness of breath affects lung and gut bacteria.
Hypoxemia, or shortness of breath, is one of the prominent symptoms for those with mild or severe coronavirus. Patients with severe cases are typically given a ventilation machine to help them breathe to bring oxygen level back up.
Previously, it was assumed that the lungs are free of bacteria, explained Shanna Ashley from the school's Division of Pulmonary and Critical Care Medicine. Now, they know 'that the balance of bacteria inside the lungs matters much as it does in the gut.
Lung Microbiome
They discovered that oxygen affects the balance of lung microbiome and disease, which can lead to lung injury or pulmonary disease. Pure oxygen is a potent lung toxin, says Dr. Robert Dickson of the Pulmonary & Critical Care Medicine and Microbiology and Immunology. Inducing mice with 100% oxygen will cause them to die in less than a week, 'and they'll have the same kind of severe lung injury that patients with COVID-19 or other lung damage have.'
Since patients in intensive care are typically treated with oxygen for extended periods, the team analyzed how therapeutic oxygen may be affecting the lung microbiome. In the study, they analyzed bacteria samples from patients who were critically ill and was on oxygen support for over 24 hours.
Bacteria species varied depending on the level of oxygen concentrations patients received. Staphylococcus aureus was commonly found in the lungs of patients who received high oxygen concentrations.
"Different types of bacteria vary quite a bit from each other in how well they can handle oxygen," Dickson said, "So we wondered if the oxygen we give our patients might be influencing the bacterial communities in their respiratory tract."
READ MORE: Coronavirus Survivors May Have Reduced Lung Function, Hong Kong Doctors Say
Oxygen Causing Lung Injury
The team observed how quickly lung bacteria changed when healthy mice were given high concentrations of oxygen. Oxygen-intolerant bacteria increased as oxygen-tolerant bacteria decreased, explained Ashley.
Three days later, Staphylococcus was the most common bacteria found in the lungs. It was also only after 72 hours the signs of lung injury was present.
In another experiment, they exposed germ-free mice to therapeutic oxygen. The mice with no microbiome had no traces of lung injury. Lung bacteria, therefore, must play a crucial role in lung injury, said Ashley.
The scientists believe that the microbiome should be a target for antibiotic therapy for patients who are using a ventilator to reduce the risk of lung damage. One antibiotic that doctors can administer is Vancomycin, which targets bacteria such as Staphylococcus without damaging the lungs.
Dickson and the team still need to do further research so they can figure out how to manipulate the lung microbiome for patients that need oxygen support. Randomized controlled trials need to be conducted to help doctors decide more accurate doses of oxygen for critically ill patients.
READ NEXT: Traces of Lung Damage Found in Asymptomatic People
Check out more news and information on COVID-19 on Science Times.
