The interdisciplinary study, published in the journal Environmental Microbiology , has important implications for the treatment of infectious diseases, which are known to be increased in areas with high levels of air pollution. The study looked into how air pollution—specifically black carbon—affects the bacteria living in the respiratory tract—the nose, throat and lungs. Black carbon, a major component of particulate matter, is produced through the burning of fossil fuels such as diesel, biofuels, and biomass.

Researchers from the University of Leicester (UK) have shown for the first time that black carbon, a major component of air pollution, directly affects bacteria that cause respiratory infections— Streptococcus pneumoniae and Staphylococcus aureus —thereby increasing the potential for infection and changing the effectiveness of antibiotic treatment. S. pneumoniae is the leading bacterial cause of pneumonia, and S. aureus is a significant cause of respiratory and skin and tissue disease.

Data from the study shows that black carbon induces changes in biofilm formation, structure, and function. The research team found that black carbon alters the antibiotic tolerance of Staphylococcus aureus communities and importantly increases the resistance of communities of Streptococcus pneumoniae to penicillin, the front line treatment of bacterial pneumonia.

(BC differentially alters the tolerance of biofilms to proteolytic degradation and multiple antibiotics, increasing S. pneumoniae survival against penicillin.)



The effect of black carbon on S. pneumoniae biofilm structure. Biofilms of S. pneumoniae were cultured in the presence or absence of 30 - 100 μg/ml BC. Biofilms were imaged by Scanning Electron Microscopy (SEM) at increasing resolutions (a-d). Hussey et al. Click to enlarge.

Furthermore, it was found that black carbon caused Streptococcus pneumoniae to spread from the nose to the lower respiratory tract (from nasopharynx to lungs), which is essential for subsequent infection.

This work increases our understanding of how air pollution affects human health. It shows 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. Our research could initiate an entirely new understanding of how air pollution affects human health. It will lead to enhancement of research to understand how air pollution leads to severe respiratory problems and perturbs the environmental cycles essential for life. —Dr Julie Morrissey, Associate Professor in Microbial Genetics in the University of Leicester’s Department of Genetics and corresponding author

The World Health Organization describes air pollution as the “largest single environmental health risk”. Air pollution is thought to be responsible for at least 7 million deaths per year, which equates to an eighth of all global deaths. The UK and many other countries around the world continue to breach the recommended pollution limits set by the World Health Organization.

Europe and North America only account for about 13% of global BC emissions, whereas developing countries are responsible for ~80 %, with the biggest global contributors to BC being China and India.

The four-year study was conducted by a University of Leicester’s College of Medicine, Biological Sciences and Psychology PhD studentship, and research grants from The Leverhulme Trust and the Natural Environment Research Council (NERC).

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