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Harmless No More? Bacteria Prevalent in Respiratory Tract Identified as Key Factor in the Worsening of Lung Disease

In a breakthrough by an international team of researchers, with researchers from Nanyang Technological University’s Lee Kong Chian School of Medicine in the lead, Neisseria subflava has been identified as the key factor behind the worsening of bronchiectasis, and may also cause infections with pre-existing asthma and chronic obstructive pulmonary disease (COPD).

Nanyang Technological University’s Lee Kong Chian School of Medicine has found that the Neisseria genus of bacteria is more harmful than expected, and is responsible for infections in patients with pre-existing conditions like asthma, bronchiectasis, and chronic obstructive pulmonary disease (COPD). Their findings were published in Cell Host & Microbe.

The team found conclusive evidence that Neisseria bacteria can cause lung disease and can worsen pre-existing bronchiectasis (another type of lung disease). Previously, this species has only been acknowledged as the cause behind gonorrhoea, a common sexually transmitted infection (STI), as well as meningitis, the inflammation of the protective membranes around the brain and spinal cord.

Bronchiectasis is a chronic disease in which a patient’s airways become abnormally enlarged. The cause of this condition remains largely unknown for up to half of Singaporean patients. It is more prevalent among Asians and may also occur during recovery from tuberculosis. It occurs in 10.6 out of 100,000 people and its risk increases with age, often arising out of the blue.

To figure out why bronchiectasis worsens at a faster rate in older Asians, the international team of researchers compared and analysed disease and infection data on bronchiectasis from Asian patients with data from their European counterparts. Through their intensive efforts, they found that Neisseria bacteria was predominantly found in the microbiome of Asian patients that experienced the worsening of their bronchiectasis.

In particular, the species of bacteria present in worsening cases of bronchiectasis, as well as exacerbations (repeat cases), was identified to be Neisseria subflava (N. subflava). Before this, N. subflava had not been linked to lung infections and was only known for its prevalence in the oral mucosa, throat, and upper airways of humans.

After further tests, the scientists confirmed that N. subflava is responsible for cell disruption, causing inflammation and immune dysfunction in bronchiectasis patients afflicted by it.

This is the first time that Neisseria has been determined to be a factor behind lung infection and worsening of disease in bronchiectasis patients.

The lead investigator, Associate Professor Sanjay Chotirmall of NTU’s Lee Kong Chian School of Medicine, reflected on the importance of his team’s discovery for the treatment of bronchiectasis patients, saying that it opens more avenues for personalised therapy of patients with consistently worsening bronchiectasis symptoms, for greater rates of recovery.

Moving forward, the researchers are considering conducting further studies and clinical trials for therapies that allow for the elimination of Neisseria from the microbiome. They seek to develop a treatment plan to target Neisseria with antibiotics upon its identification and hope that such a treatment will improve lung infection patient outcomes. [APBN]

Source: Li et al. (2022). Neisseria species as pathobionts in bronchiectasis. Cell Host & Microbe, 30(9), 1311-1327.