Vape mouthpieces could be swarming with fungi that harm airways

An array of fungi, some of which have been linked to lung complications, have been collected from e-cigarette mouthpieces.

The use of vapes is generally recommended as a way to transition away from smoking, but their long-term health impacts are poorly understood.

In vapes, a battery-powered coil heats a liquid that typically contains nicotine, producing vapour that is inhaled by users. Health concerns have largely centred on the toxicity of the liquid’s chemical constituents, so no one has tried to understand which microbes may make their way from the devices into users’ airways.

To learn more, Borna Mehrad and his colleagues at the University of Florida recruited 25 people who used disposable vapes every day. The researchers cultured the microbes from the mouthpieces of their devices, comparing them to those in the volunteers’ mouths.

Only a small number of the vapes contained bacteria. But according to the researchers, more than half were “abundantly colonized” with fungi species that were distinct from those in the volunteers’ mouths – and 80 per cent of them are capable of causing ill health in people.

The most common of these species was Cystobasidium minutum, which has been linked to blood infections among people with suppressed immune systems. To understand how it could affect the lungs, the team had mice inhale C. minutum, mimicking the entry method of vaping.

“We found that the fungus that was most prevalent in the vape samples caused features of chronic bronchitis in mice,” says Mehrad. This is defined as inflammation of the airways, which can cause flu-like symptoms.

As to where these fungi came from, some are present in the air and on our hands, but team member Jason Smith says they may have already been in the vape liquids when purchased, though the researchers didn’t test them for this. “The residues left behind inside the vape device may provide a food source for moulds to grow,” he adds.

Ian Musgrave at the University of Adelaide in Australia says fungi have been found in shisha, also known as hookahs or waterpipes, and there is evidence that this method of smoking has contributed to microbial-induced lung disease. “What is interesting is that the microbiota found in this study were dominated by potentially pathogenic fungi, which are rare in the mouth microbiome,” he says.

Team member Katy Deitz says she wasn’t surprised by the findings given that most participants – around a third of whom reported having respiratory symptoms, such as coughing – didn’t clean their vapes.

Musgrave recommends vapes be cleaned regularly, but stresses that there isn’t enough evidence to conclude that these fungal species exist in high enough numbers on vape mouthpieces to cause ill health.