How many bacterial species can live on human hands?

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Bacteria A scanning electron micrograph of gram-positive *Mycobacterium tuberculosis* bacteria, the cause of tuberculosis and scrofula.

Research indicates that a typical palm surface of a human hand can harbor more than 150 different bacterial species.1

This microbial population is highly diverse, with significant variation observed between individuals and even between the right and left hands of the same person. Studies have shown that only about 17 percent of the bacterial species found on one hand are common to the other hand of the same individual, and only 13 percent are shared between different people. This diversity is a component of the broader human microbiome, which consists of a vast array of microorganisms living on and in the human body.1