Bacteria 'clouds' traceable to individuals

Friday September 25th, 2015

Humans emit a personal microbial cloud, traceable to each individual, researchers have reported.

So called "human-associated bacteria" are known to disperse into the environment via direct contact with surfaces and particle emission from our breath, clothes, skin and hair.

Recent studies have mainly focused on direct human contact with surfaces, explain researchers led by Dr James Meadow at the University of Oregon, USA. These studies have shown that people leave behind bacterial signatures indicative of particular body parts and types of bodily contact.

Now, the team can demonstrate that "humans emit a detectible microbial cloud into surrounding indoor air". They used gene sequencing to link back airborne bacteria to 11 participants sitting in sanitised climate chambers.

"Most occupants could be clearly detected by their airborne bacterial emissions, as well as their contribution to settled particles, within 90 minutes to four hours," the team writes in the journal PeerJ.

"Our results demonstrate for the first time that individuals release their own personalised microbial cloud," they conclude.

Several groups of bacteria were present at different levels and combinations in the participants' microbial clouds. For example, one group is Streptococcus, commonly found in the mouth. Another is Propionibacterium, commonly found on the skin, as is Corynebacterium.

The team say this research may help understand of how infectious diseases spread throughout buildings, and might contribute towards new methods for tracing an individual's past presence in an indoor space.

They add that their findings suggest that increasing air flow rates from one to three Air Changes per Hour "nearly eliminates the detectible human microbial cloud".

Meadow, J. F. et al. Humans differ in their personal microbial cloud. PeerJ 22 September 2015 doi.org/10.7717/peerj.1258 [abstract]

Tags: General Health | North America

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