E-cigarette vapor makes people more vulnerable to superbugs, scientists have revealed.

A new study claims e-cigarettes are toxic to human airway cells, suppress immune defenses and cause inflammation in the body.

Furthermore, the vapor from e-cigarettes also boosts the capacity of the bacteria to cause disease, according to researchers from University of California, San Diego.

Senior study author Dr Laura Crotty Alexander said: ‘This study shows that e-cigarette vapor is not benign – at high doses it can directly kill lung cells, which is frightening.

E-cigarette vapor is toxic to human airway cells and suppresses immune defenses - which makes people vulnerable to superbugs, scientists have revealed

‘We already knew that inhaling headed chemicals, including the e-liquid ingredients nicotine and propylene glycol, couldn’t possibly be good for you.

‘This work confirms that inhalation of e-cigarette vapor daily leads to changes in the inflammatory milieu inside the airways.’

An estimated 2.6 million adults in the UK use e-cigarettes – often in an attempt to cut down on tobacco smoking.

That equates to nearly 17.6 per cent of all smokers.

Meanwhile, the Centers for Disease Control revealed 12.6 per cent of US adults said in 2014 that they had tried an e-cigarette in their lifetime.

This study shows e-cigarette vapor is not benign – at high doses it can directly kill lung cells, which is frightening Dr Laura Crotty Alexander, of University of California, San Diego

And, among those who are trying to quit smoking, nearly 20 percent are current e-cigarette users.

The study exposed mice to e-cigarette vapor.

The scientists found that inflammatory markers in mice – which inhaled vapor for an hour a day, five days a week for four weeks – were elevated 10 per cent, as compared to unexposed mice.

Dr Crotty Alexander said the inflammatory changes were likely to cause disease eventually.

‘We don’t know specifically which lung and systemic diseases will be caused by the inflammatory changes induced by e-cigarette vapor inhalation, but based on clinical reports of acute toxicities and what we have found in the lab, we believe that they will cause disease in the end,' she said.

‘Some of the changes we found in mice are also found in the airways and blood of conventional cigarette smokers, while others are found in humans with cancer of inflammatory lung diseases.’

However, the study found that bacterial pathogens exposed to e-cigarette vapor benefited.

The antibiotic-resistant bacteria staphylococcus aureus (pictured) were found to be better able to adhere to and invade airway cells after e-cigarette vapor exposure, according to the study

Staphylococcus aureus bacteria were better able to form biofilms, adhere to and invade airway cells and resist human antimicrobial peptides after exposure.

The study also found that e-cigarette vapor extract-bacteria were more virulent in a mouse model of pneumonia.

Mice infected with normal methicllinin-resistant S.aureus (MRSA) – with is an antibiotic-resistant superbug – survived.

However, mice infected with MRSA that were pre-exposed to e-cigarette vapor died.

The scientists said the results were consistent with e-liquids from seven different manufacturers – showing that the findings were not limited to one formula or brand.