About superficial skin infections (SSIs)

Superficial skin infections (SSIs) are infections that appear on the skin’s surface and can be caused by numerous external factors, such as viruses, bacteria, fungi or parasites.

These infections lead to a variety of conditions and severities, depending on the location and extent of the infection. Types of SSI include impetigo, folliculitis, furuncles (boils) and carbuncles.

The two most common bacterial infections leading to SSIs are caused by the bacteria Staphylococcus aureus and Streptococcus. These bacteria are commonly found on the skin and nose but a break in the skin, such as a cut, scratch or insect bite, can allow these bacteria to enter the body, leading to an SSI. Risk factors for primary SSIs (i.e. infections of healthy skin) include excessive heat or sweat, friction from tight clothing or shaving, or ingrown hairs. Alternatively, secondary SSIs can occur when bacteria enter areas of skin that are already wounded, diseased, or that have experienced a recent trauma.


Aly R. Chapter 98. Microbial Infections of Skin and Nails. Medical Microbiology (4th ed). Galveston (TX): University of Texas Medical Branch at Galveston; 1996.

Mayo Clinic. 2019. Boils and carbuncles. [ONLINE] Avalible at: https://www.mayoclinic.org/diseases-conditions/boils-and-carbuncles/symptoms-causes/syc-20353770[Accessed Oct 2019]

Mayo Clinic. 2019. Folliculitis. [ONLINE] Avalible at: https://www.mayoclinic.org/diseases-conditions/folliculitis/symptoms-causes/syc-20361634 [Accessed Oct 2019].

Medline Plus. 2016. Impetigo. [ONLINE] Avalible at: https://medlineplus.gov/impetigo.html# [Accessed Oct 2019].