Scientists discover bacteria found in armpits and groins in Earth’s atmosphere

Scientists from Spain and Japan have discovered a whole host of bacteria and fungi in a layer of Earth's atmosphere known as the planetary boundary layer or troposphere – including E. coli and one particular organism commonly found in the most unusual of places.

Samples were taken at altitudes of up to 3,000 metres (more than 9,800 feet – commercial flights tend to cruise from 30,000 feet, for comparison) across 10 flights over Japan, with the scientists finding that the bacteria and fungi discovered in the samples had travelled more than 2,000 kilometres from its original location.

Xavier Rodó of the Barcelona Institute for Global Health, which led the study, said: “Our findings uncover a rich and unprecedented diversity of microbes that are dispersed by wind currents thousands of kilometres away from their sources by intense tunnels of wind that form high in the troposphere.

“They represent a paradigm shift in our understanding of how human health can be affected by pathogens thriving in the environment, particularly in the air.”

The study, published in Proceedings of the National Academy of Sciences on Monday, ‘unearthed’ (pun very much intended) more than 266 fungi and 305 bacteria, with some potentially pathogenic for plants and animals – including humans.

Some were even found to be resistant to common antibiotics - such as micrococcus luteus, which can cause infections in immunocompromised people.

Organisms listed by the study authors include Cutibacterium acnes (which, as the name suggests, can cause acne), Clostridium botulinum (which produces a neurotoxin which can cause the rare but life-threatening condition called botulism) and Staphylococcus haemolyticus.

That last one is particularly bizarre, because it is found among our “normal skin flora” (that is, microorganisms on the skin) – and “commonly isolated from the axillae, perineum, and inguinal areas of humans”, as a study from 2005 puts it.

In general terms, this means the “usually harmless” bacteria – which can cause wound infections, conjunctivitis and catheter-related urinary tract infections – can be found in a person’s armpits, that bit between their anus and scrotum/vulva, and/or the groin respectively.

Lovely.

The academics stress that their study “does not prove a causal link between the presence of known human pathogens in aerosols and health effects”, though.

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