Air Pollution May Cause Bacteria Changes in Respiratory Tract

 The WHO says air pollution is the largest environmental risk factor for human disease. The WHO says air pollution is the largest environmental risk factor for human disease.

New research suggests that air pollution may have an effect on human health by altering bacteria. It shows that black carbon, a major component of air pollution, dramatically changes how bacteria grow and form biofilms, which can affect their survival in the lining of airways and their resistance to antibiotics.

The study - by researchers from the University of Leicester in the United Kingdom - is published in the journal Environmental Microbiology.

The team suggests that the work may have important implications for the treatment of infectious diseases, which are known to occur more frequently in places with high levels of air pollution.

First author Julie Morrissey, associate professor in microbial genetics, says that the findings show “that the bacteria which cause respiratory infections are affected by air pollution, possibly increasing the risk of infection and the effectiveness of antibiotic treatment of these illnesses.”

According to the World Health Organization (WHO), air pollution is the largest environmental risk factor for human disease. In 2012, around 1 in 8 deaths worldwide were due to exposure to air pollution.

A recent analysis also confirms that 92% of the world’s population lives in places where air quality levels exceed WHO limits.

Particulate matter, such as black carbon, is thought to be one of the main components of air pollution, and its effects on human health are well established. Black carbon is produced through the burning of fossil fuels including diesel, biomass, and biofuels.

For example, studies have shown that exposure to black carbon is linked with cardiopulmonary disease and deaths, and that black carbon may also cause disease by carrying a wide range of chemicals, varying in toxicity, into the human body.

  Poorly Understood

However, as Morrissey and colleagues note, the effects of black carbon on bacteria, “organisms central to ecosystems in humans and in the natural environment, are poorly understood.”

For their study, they investigated how black carbon affects bacteria living in the respiratory tract - that is, the nose, the throat, and the lungs.

They focused on two bacteria that are major causes of respiratory disease in humans and show high levels of resistance to antibiotics: Staphylococcus aureus and Streptococcus pneumoniae. Both of these bacteria are in the WHO’s global list of 12 priority pathogens.

Researchers found that black carbon alters the antibiotic tolerance of S. aureus biofilms and increased the ability of S. pneumoniae biofilms to resist penicillin, the front-line drug for treating bacterial pneumonia.

Biofilms form when bacteria cells stick to surfaces and form communities held together by a slimy, glue-like substance that they excrete and surround themselves with. These surfaces can include living tissue, such as of the heart and lungs.

The findings show that “exposure to black carbon induces structural, compositional, and functional changes in the biofilms of both S. pneumoniae and S. aureus.”

They conclude that their study “highlights that air pollution has a significant effect on bacteria that has been largely overlooked.”

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