This article needs additional citations for verification. (September 2019)
A skin infection is an infection of the skin in humans and other animals, that can also affect the associated soft tissues such as loose connective tissue and mucous membranes. They comprise a category of infections termed skin and skin structure infections (SSSIs), or skin and soft tissue infections (SSTIs), and acute bacterial SSSIs (ABSSSIs). They are distinguished from dermatitis (inflammation of the skin), although skin infections can result in skin inflammation.
Bacterial skin infections affected about 155 million people and cellulitis occurred in about 600 million people in 2013. Bacterial skin infections include:
- Cellulitis, a diffuse inflammation of connective tissue with severe inflammation of dermal and subcutaneous layers of the skin. Further, cellulitis can be classified based into purulent and non-purulent cellulitis, based on the most likely causative agent and the symptoms presentation. Purulent cellulitis is often caused by Staphylococcus aureus, including both methicillin-sensitive (MSSA) and methicillin-resistant S. aureus (MRSA). Non-purulent cellulitis is most often associated with group A beta-hemolytic streptococci, such as Streptococcus pyogenes. In rare cases, the infection can progress into necrotizing fasciitis, a serious and potentially fatal infection.
- Erysipelas, is a bacterial infection which primarily effects superficial dermis, and often involves superficial lymphatics. Unlike cellulitis, it does not effect deeper layers of the skin. It is primarily caused by the Group A beta-hemolytic streptococci, with Streptococcus pyogenes being the most common pathogen.
- Folliculitis, is a skin condition in which hair follicle, located in the dermal layer of the skin, becomes infected and inflamed. It is predominantly caused by bacterial infections, especially Staphylococcus aureus, leading to superficial bacterial folliculitis. Other causative agents of folliculitis include fungi (most commonly Malassezia species), viruses (such as herpes simplex virus), and mites (Demodex species).
- Impetigo, a highly contagious ABSSSI (acute bacterial skin and skin structure infection) common among pre-school children, primarily associated with the pathogens S. aureus and S. pyogenes. Impetigo has a characteristic appearance with yellow (honey-coloured), crusted lesions occurring around mouth, nose, and chin. It is estimated, that at any given time, it effects 140 million people globally. Impetigo can be further classified into bullous and nonbullous forms. Nonbullous impetigo is the most common form, representing approximately 70% of diagnosed cases. The remaining 30% of cases represent bullous form, which is primarily caused by S. aureus.  In rare instances, bullous impetigo can spread and lead to Staphylococcal Scalded Skin Syndrome (SSSS), a potentially life-threatening infection.
Fungal skin infections may present as either a superficial or deep infection of the skin, hair, and/or nails. Mycetoma are a broad group of fungal infections that characteristically originate in the skin and subcutaneous tissues of the foot. If not treated appropriately and in a timely fashion mycetoma infections can extend to deeper tissues like bones and joints causing osteomyelitis. Extensive osteomyelitis can necessitate surgical bone resections and even lower limb amputation. As of 2010, they affect about one billion people globally. Some examples of common fungal skin infections include:
- Dermatophytosis, also known as ringworm, is a superficial fungal infection of the skin caused by several different species of fungi. The fungal genera which cause skin infections in humans include Trichophyton, Epidermophyton, and Microsporum. Although dermatophytosis is fairly common fungal skin infection worldwide, it is more prevalent in areas with high humidity and environmental temperature. It is estimated that approximately 20-25% of world population are effected by superficial fungal infections, with dermatophytosis predominating.
- Oral candidiasis, also commonly referred to as oral thrush, is a fungal infection caused mainly by Candida albicans, which effects mucosal membranes of the oral cavity and the tongue. C. albicans accounts for approximately 95% of oral thrush cases. The fungus is part of the normal oral flora and only causes an infection when host immune and microbiota barriers are impaired, providing C. albicans with an opportunity to overgrow. It is estimated that oral candidiasis effects approximately 2 million people every year worldwide.
- Onychomycosis, is a fungal infection which predominantly effects toenails. Two most common causative agents of onychomycosis are Trichophyton mentagrophytes and Trichophyton rubrum. Common signs and symptoms include nail discolouration and thickening, nail separation from nail bed, and nail brittleness. Estimated prevalence of onychomycosis in North America is between 8.7% to 13.8%.
Parasitic infestations of the skin are caused by several phyla of organisms, including Annelida, Arthropoda, Bryozoa, Chordata, Cnidaria, Cyanobacteria, Echinodermata, Nemathelminthes, Platyhelminthes, and Protozoa.
- Warts, are benign proliferative skin lesions that are caused by human papilloma virus (HPV). Warts vary in shape, size, appearance, and location on the body where they occur. For example, plantar warts (verrucae plantaris), occur on the soles of the feet and appear as thick calluses. Other types of warts include genital warts, flat warts, mosaic warts, and periungual warts. Common treatment options include salicylic acid and cryotherapy with liquid nitrogen.
- Chickenpox, is a highly contagious skin disease caused by the varicella-zoster virus (VZV). It is characterized by pruritic blister-like rash which may cover entire body, affecting all age groups. Rates of chickenpox are higher in countries which lack adequate immunization programs. In 2014, it has been estimated that global incidence of serious chickenpox infections requiring hospitalizations was 4.2 million.
- Hand, foot, and mouth disease (HFMD), is a common, often self-limiting viral illness which typically affects infants and children, however, it may also occur in adults. It is characterized by low grade fever and maculopapular rash on palms of the hands, soles of the feet, and around mouth. It is caused by the human enteroviruses and coxsackieviruses, a positive-sense single-stranded RNA viruses.
- Stevens DL, Bisno AL, Chambers HF, Dellinger EP, Goldstein EJ, Gorbach SL, et al. (July 2014). "Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the infectious diseases society of America". Clinical Infectious Diseases. 59 (2): 147–159. doi:10.1093/cid/ciu296. PMID 24947530.
- "Guidance Compliance Regulatory Information" (PDF). www.fda.gov. Retrieved 2019-09-15.
- "International Statistical Classification of Diseases and Related Health Problems 10th Revision". apps.who.int. Retrieved 2019-09-15.
- In the WHO classification, it is noted that the infection classification "Excludes:... infective dermatitis...". See the WHO classification, op. cit.
- Skin inflammation due to skin infection is called "infective dermatitis". See the WHO classifications, op. cit.
- Vos, Theo; et al. (Global Burden of Disease Study 2013 Collaborators) (August 2015). "Global, regional, and national incidence, prevalence, and years lived with disability for 301 acute and chronic diseases and injuries in 188 countries, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013". Lancet. 386 (9995): 743–800. doi:10.1016/s0140-6736(15)60692-4. PMC 4561509. PMID 26063472.
- Raff AB, Kroshinsky D (July 2016). "Cellulitis: A Review". JAMA. 316 (3): 325–337. doi:10.1001/jama.2016.8825. PMID 27434444. S2CID 241077983.
- Breyre A, Frazee BW (November 2018). "Skin and Soft Tissue Infections in the Emergency Department". Emergency Medicine Clinics of North America. 36 (4): 723–750. doi:10.1016/j.emc.2018.06.005. PMID 30297001. S2CID 52942182.
- Chen LL, Fasolka B, Treacy C (September 2020). "Necrotizing fasciitis: A comprehensive review". Nursing. 50 (9): 34–40. doi:10.1097/01.NURSE.0000694752.85118.62. PMC 8828282. PMID 32826674.
- Clebak KT, Malone MA (September 2018). "Skin Infections". Primary Care. Infectious Disease. 45 (3): 433–454. doi:10.1016/j.pop.2018.05.004. PMID 30115333. S2CID 52022225.
- Winters R, Mitchell M (2021). "Folliculitis". StatPearls. Treasure Island (FL): StatPearls Publishing. PMID 31613534. Retrieved 2021-12-03.
- Henning MA, Jemec GB, Saunte DM (November 2020). "[Malassezia folliculitis]". Ugeskrift for Laeger. 182 (47): V08200572. PMID 33215579.
- "Impetigo". nhs.uk. October 19, 2017.
- Kumar V, Abbas AK, Fausto N, Mitchell RN (2007). Robbins Basic Pathology (8th ed.). Saunders Elsevier. p. 843. ISBN 978-1-4160-2973-1.
- Johnson MK (2020). "Impetigo". Advanced Emergency Nursing Journal. 42 (4): 262–269. doi:10.1097/TME.0000000000000320. PMID 33105179. S2CID 225081229.
- Dollani LC, Marathe KS (April 2020). "Impetigo/Staphylococcal Scalded Skin Disease". Pediatrics in Review. 41 (4): 210–212. doi:10.1542/pir.2018-0206. PMID 32238552. S2CID 214768670.
- Brazel M, Desai A, Are A, Motaparthi K (October 2021). "Staphylococcal Scalded Skin Syndrome and Bullous Impetigo". Medicina. 57 (11): 1157. doi:10.3390/medicina57111157. PMC 8623226. PMID 34833375.
- Verma P, Jha A (March 2019). "Mycetoma: reviewing a neglected disease". Clinical and Experimental Dermatology. 44 (2): 123–129. doi:10.1111/ced.13642. PMID 29808607. S2CID 44123860.
- El-Sobky TA, Haleem JF, Samir S (21 September 2015). "Eumycetoma Osteomyelitis of the Calcaneus in a Child: A Radiologic-Pathologic Correlation following Total Calcanectomy". Case Reports in Pathology. 2015: 129020. doi:10.1155/2015/129020. PMC 4592886. PMID 26483983. S2CID 15644051.
- Vos T, Flaxman AD, Naghavi M, Lozano R, Michaud C, Ezzati M, et al. (December 2012). "Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010". Lancet. 380 (9859): 2163–2196. doi:10.1016/S0140-6736(12)61729-2. PMC 6350784. PMID 23245607.
- Jartarkar SR, Patil A, Goldust Y, Cockerell CJ, Schwartz RA, Grabbe S, Goldust M (December 2021). "Pathogenesis, Immunology and Management of Dermatophytosis". Journal of Fungi. 8 (1): 39. doi:10.3390/jof8010039. PMC 8781719. PMID 35049979.
- Begum J, Mir NA, Lingaraju MC, Buyamayum B, Dev K (April 2020). "Recent advances in the diagnosis of dermatophytosis". Journal of Basic Microbiology. 60 (4): 293–303. doi:10.1002/jobm.201900675. PMID 32003043. S2CID 210983216.
- Vila T, Sultan AS, Montelongo-Jauregui D, Jabra-Rizk MA (January 2020). "Oral Candidiasis: A Disease of Opportunity". Journal of Fungi. 6 (1): 15. doi:10.3390/jof6010015. PMC 7151112. PMID 31963180.
- Quindós G, Gil-Alonso S, Marcos-Arias C, Sevillano E, Mateo E, Jauregizar N, Eraso E (March 2019). "Therapeutic tools for oral candidiasis: Current and new antifungal drugs". Medicina Oral, Patologia Oral y Cirugia Bucal. 24 (2): e172–e180. doi:10.4317/medoral.22978. PMC 6441600. PMID 30818309.
- Bongomin F, Gago S, Oladele RO, Denning DW (October 2017). "Global and Multi-National Prevalence of Fungal Diseases-Estimate Precision". Journal of Fungi. 3 (4): 57. doi:10.3390/jof3040057. PMC 5753159. PMID 29371573.
- Leung AK, Lam JM, Leong KF, Hon KL, Barankin B, Leung AA, Wong AH (2020). "Onychomycosis: An Updated Review". Recent Patents on Inflammation & Allergy Drug Discovery. 14 (1): 32–45. doi:10.2174/1872213X13666191026090713. PMC 7509699. PMID 31738146.
- Gupta AK, Stec N, Summerbell RC, Shear NH, Piguet V, Tosti A, Piraccini BM (September 2020). "Onychomycosis: a review". Journal of the European Academy of Dermatology and Venereology. 34 (9): 1972–1990. doi:10.1111/jdv.16394. PMID 32239567. S2CID 214768942.
- Diaz JH (January 2010). "Mite-transmitted dermatoses and infectious diseases in returning travelers". Journal of Travel Medicine. 17 (1): 21–31. doi:10.1111/j.1708-8305.2009.00352.x. PMID 20074098.
- Lebwohl MG, Rosen T, Stockfleth E (November 2010). "The role of human papillomavirus in common skin conditions: current viewpoints and therapeutic options". Cutis. 86 (5): suppl 1–11, quiz suppl 12. PMID 21214125.
- Mulhem E, Pinelis S (August 2011). "Treatment of nongenital cutaneous warts". American Family Physician. 84 (3): 288–293. PMID 21842775.
- Soenjoyo KR, Chua BW, Wee LW, Koh MJ, Ang SB (November 2020). "Treatment of cutaneous viral warts in children: A review". Dermatologic Therapy. 33 (6): e14034. doi:10.1111/dth.14034. PMID 32683782. S2CID 220655257.
- Witchey DJ, Witchey NB, Roth-Kauffman MM, Kauffman MK (February 2018). "Plantar Warts: Epidemiology, Pathophysiology, and Clinical Management". The Journal of the American Osteopathic Association. 118 (2): 92–105. doi:10.7556/jaoa.2018.024. PMID 29379975. S2CID 25371618.
- Freer G, Pistello M (April 2018). "Varicella-zoster virus infection: natural history, clinical manifestations, immunity and current and future vaccination strategies". The New Microbiologica. 41 (2): 95–105. PMID 29498740.
- "About Chickenpox | CDC". www.cdc.gov. 2022-03-23. Retrieved 2022-04-24.
- Wutzler P, Bonanni P, Burgess M, Gershon A, Sáfadi MA, Casabona G (August 2017). "Varicella vaccination - the global experience". Expert Review of Vaccines. 16 (8): 833–843. doi:10.1080/14760584.2017.1343669. PMC 5739310. PMID 28644696.
- Esposito S, Principi N (March 2018). "Hand, foot and mouth disease: current knowledge on clinical manifestations, epidemiology, aetiology and prevention". European Journal of Clinical Microbiology & Infectious Diseases. 37 (3): 391–398. doi:10.1007/s10096-018-3206-x. PMID 29411190. S2CID 3376169.
- Saguil A, Kane SF, Lauters R, Mercado MG (October 2019). "Hand-Foot-and-Mouth Disease: Rapid Evidence Review". American Family Physician. 100 (7): 408–414. PMID 31573162.