Which bacterial species predominantly colonizes human skin?

Staphylococcus epidermidis is the bacterial species that predominantly colonizes human skin. This organism is a type of coagulase-negative staphylococci and is a natural inhabitant of the skin and mucous membranes in humans. It plays a significant role in the skin's normal flora and contributes to the maintenance of skin health by inhibiting the growth of more pathogenic microorganisms through competition for resources and production of antimicrobial substances.

The presence of Staphylococcus epidermidis is beneficial under normal circumstances as it can help prevent infections. However, it can also be an opportunistic pathogen, particularly in individuals with compromised immune systems or in cases where invasive procedures introduce it into deeper tissues.

In contrast, Lactobacillus primarily inhabits the gastrointestinal tract and female reproductive system, where it plays a role in maintaining a healthy microbiome, but it is not a predominant skin inhabitant. Candida albicans is a yeast that can also be found in the human microbiota, particularly in areas like the mouth and genital region, but it is not a dominant skin colonizer. Streptococcus pneumoniae is a bacterium commonly associated with respiratory infections and does not typically colonize the skin.

Thus, Staphylococcus epidermidis is the correct choice as it is specifically