Study highlights hidden hazards of airborne antibiotic-resistance genes

People are often notified about poor air quality by weather apps, and this happens frequently in urban areas, where levels of outdoor pollution containing particulates and soot are high. But now scientists are reporting in ACS' Environmental Science & Technology that there is another type of air contaminant that they say isn't receiving enough attention: antibiotic-resistance genes.

According to the U.S. Centers for Disease Control and Prevention, at least 2 million people in the U.S. become infected with antibiotic-resistant bacteria every year. Research has shown that antibiotic resistant genes (ARGs) can move from bacteria to bacteria, or even from bacteria to the environment. For example, tetracycline-resistance genes have been found near animal feed operations, and β-lactam-resistance genes have been found in urban parks in California. These studies indicated that airborne transmission could be a factor in the spreading and exposure of ARGs. But current air pollution investigations typically don't take ARGs into account. So, Maosheng Yao and colleagues wanted to examine airborne ARGs on a global scale.

The team performed a survey of 30 ARGs across 19 cities around the world, including San Francisco, Beijing and Paris. The group studied ARGs resistant to seven common classes of antibiotics: quinolones, β-lactams, macrolides, tetracyclines, sulfonamides, aminoglycosides and vancomycins. Beijing had the most diverse group of airborne ARGs, with 18 different subtypes detected, while San Francisco had the highest overall level of airborne ARGs. Genes resistant to β-lactams and quinolones were the two most abundant types of ARGs in all the cities studied. Low levels of ARGs resistant to vancomycin, an antibiotic of last resort for MRSA treatment, were found in the air of six cities.