Known as the Jekyll and Hyde bacteria, it can cause big problems if it "switches character", but scientists appear to have found a way to stop it.
The research team found they were able to deactivate a protein critical to the survival of the bacteria, which colonises the respiratory tract from early childhood.
Associate Professor Ulrike Kappler said the bacteria was an example of the classic 'Dr Jekyll and Mr Hyde' story, causing problems if it 'switched character'.
"Most of the time, these bacteria are harmless inhabitants of the respiratory tract, but they have the potential to shift their behaviour and cause diseases such as pneumonia and middle ear infections," Dr Kappler said.
"More sinisterly, these bacteria can worsen asthma and bronchiectasis and slow recovery from viruses including COVID-19.
"In people with cystic fibrosis, Haemophilus can promote colonisation of the lungs by other disease-causing bacteria..."
Dr Kappler said the team found the bacteria relied heavily on the LldD protein, found in the bacterial cell membrane, for nutrition and survival.
"By deactivating the 'LldD' protein in Haemophilus to starve the bacteria of key nutrients, the population of damaging bacteria present during infection collapsed, with more than 99.9 per cent eliminated," Dr Kappler said.
PhD candidate Jennifer Hosmer said the findings were an important first step, which would inform future research into how to treat patients who had developed serious infections due to the bacteria.
"It's a really exciting time, and we feel we're another step closer to solving the puzzle of how to treat respiratory diseases and infections that afflict millions of people across the globe," she said.
She said researchers also learned that the bacteria did not compete with human cells for the use of glucose to generate energy, but actually fed off waste products such as lactate.
"Surprisingly, Haemophilus also use the human cellular waste products against us by converting them into a form that tricks our immune system to ignore them, meaning our body is unable to keep their numbers in check."
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