By Tobias Bolli, Junior Project Manager Academic Relations
Humans are experts at detecting and reacting to visible dangers around them. We have no trouble making out a car racing towards us and speeding up to get out of its way; we are experts at picking up on body language and deducing (for instance) that this guy at the bar has had a few beers too many. We might, in other words, be very aware of all the dangers encountered on a macro-scale. What doesn’t announce itself to our eyes, however, quite often goes unnoticed.
Our very first installment of the Connected series (June 9, 2020) zoomed in on what cannot be seen: airborne pathogens with SARS-CoV-2 (the virus causing COVID-19) featuring as a prominent example. Prof. Dr. Jing Wang, associate professor at the Institute of Environmental Engineering at ETH Zurich, started out by talking about indicators of air quality in general. Many people may be familiar with PM10 and PM2.5 as a way of measuring air quality. PM stands for particle matter and the number following it for the size of the particles (PM10 designating particles between 2.5 and 10 micrometers (one millionth of a meter), and PM2.5 standing for particles measuring 2.5 micrometers or less).
A slide by Prof. Dr. Wang comparing the concentration of pathogens in cities all around the globe.
While these numbers can provide a good indication of air quality, they don’t provide the full picture. Prof. Dr. Wang underscored that it is just as important to know what the particles actually consist of, since some pose a significantly greater risk than others. Generally speaking, we find organic as well as inorganic matter in the air, heavy metals being an example for inorganic compounds, with bacteria, fungi, viruses as well as pollens constituting examples for organic particles. These so called bioaerosols all have biological origins, stemming from plants, animals or humans.
Prof. Dr. Wang presented a global survey which compared the prevalence of antibiotic resistant genes (ARGs) in cities around the world. It showed that high amounts of PM10 and PM2.5 don’t necessarily correlate with high amounts of ARGs, with San Francisco having relatively low amounts of particle matters, but still a pretty high concentration of ARGs. He pointed out that there is a clear correlation between the use of antibiotics and the amount of antibiotic resistant bacteria in the air. Simply put, the more antibiotics one uses, the higher the concentration of ARGs in the urban air.
A slide showing parts of the measuring instruments used by Prof. Dr. Wang.
As Prof. Dr. Wang showed, there are a host of different methods to measure airborne pathogens. Going beyond traditional methods, he presented an innovative approach which relies on electromagnetic fields to detect surface features. Incoming lights interact with nanoparticles on the target material; this leads to characteristic electromagnetic fields which can be enhanced to get a meaningful signal. For his novel approach to detecting SARS-CoV-2, Prof. Dr. Wang made use of temperature effects to be able to distinguish between this virus and related ones such as the original SARS virus (SARS-CoV). Importantly, he was able to use this method as an alternative way of diagnosing the disease - and is on course to making this instrument capable of detecting SARS-CoV-2 in ambient air as well.
The second presentation revolved around antibiotic resistant bacteria related to animal farming. Prof. Dr. Min Gao pointed out that, according to WHO, at least 700´000 people die each year due to drug resistant bacteria. A number that could rise to 10 million by 2050 if no action is taken. To further drive home the scale and severity of the problem, Prof. Dr. Gao quoted the WHO which considered a post-antibiotic world - a world in which minor injuries can have lethal effects because there aren’t any effective antibiotics anymore to treat infections - not an apocalyptic fantasy but a very real scenario. The driver behind increased antibiotic resistance is the use of antibiotics which leads to selection pressure and bacteria adapting to that pressure. Importantly, around 73% of antibiotics are used in animal farming which can thus be considered the main contributor to this trend.
Our two panelists from top left to right: Prof. Dr. Jing Wang, Prof. Dr. Min Gao as well as our moderator Gu Libing in bottom center.
As Prof. Dr. Gao made clear, antibiotic resistant genes and bacteria aren’t staying inside animal farms. Rather, ARGs are abundant in urban air as well and have an astounding ability of traveling huge distances. Thus, ARGs can attach themselves to other particles and be transported from Asia all the way over the Pacific to the West of the United States. Similarly, sandstorms can transport ARGs from African countries all the way to Europe. Even if one lives far away from animal farms, one still might be affected by their output then. As part of her research project, Prof. Dr. Gao collected particle samples inside and outside of Chinese animal farms. She found almost 2000 ARGs which are resistant to 15 major antibiotics inside of animal farms, and 800 such pathogens in the urban air. All of them, it turned out, are resistant to penicillin. Luckily, however, she couldn’t find a pathogen resistant to vancomycin, which can thus still be used as an effective treatment in many cases.
A slide illustrating some of the results of Prof. Dr. Gao’s research.
During the Q&A session Prof. Dr. Wang clarified that the SARS-CoV-2 measuring instrument he developed is still very much a lab-instrument, requiring manual input and a number of steps until a result is generated. He is optimistic, however, that the first units can be deployed in 10 months with further improvements on the horizon. Prof. Dr. Gao said that the source of bioaerosol in animal farms is not so much the coughing of animals (although that is a source too) as the manure which leads to a spread of these pathogens. Asked about whether she is worried about her research results, she said that at this moment in time we still have some back-up antibiotics which work and that a “super bug” is not inevitable. To keep the situation from deteriorating, Prof. Dr. Gao suggested that we decrease the use of antibiotics, which would naturally result in a decrease of antibiotic resistance as well.
Suffice it to say, we like to thank both our speakers for giving us a glimpse into their fascinating research and for their generous interaction with the audience!
Please find a link to the slides and webinar recording below:
