Skin infection#Bacterial
{{Short description|Infections of the skin}}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.{{citation needed|date=September 2019}} They comprise a category of infections termed skin and skin structure infections (SSSIs), or skin and soft tissue infections (SSTIs),{{cite journal | vauthors = Stevens DL, Bisno AL, Chambers HF, Dellinger EP, Goldstein EJ, Gorbach SL, Hirschmann JV, Kaplan SL, Montoya JG, Wade JC | display-authors = 6 | title = Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the infectious diseases society of America | journal = Clinical Infectious Diseases | volume = 59 | issue = 2 | pages = 147–159 | date = July 2014 | pmid = 24947530 | doi = 10.1093/cid/ciu296 | doi-access = free | author-link6 = Sherwood Gorbach }} and acute bacterial SSSIs (ABSSSIs).{{cite web|url=https://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/ucm071185.pdf |archive-url=https://web.archive.org/web/20090710001127/http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/ucm071185.pdf |url-status=dead |archive-date=July 10, 2009 |title=Guidance Compliance Regulatory Information |website=www.fda.gov |access-date=2019-09-15}} They are distinguished from dermatitis (inflammation of the skin),{{cite web|url=http://apps.who.int/classifications/apps/icd/icd10online/?gl20.htm |title=International Statistical Classification of Diseases and Related Health Problems 10th Revision |website=apps.who.int |access-date=2019-09-15}}In the WHO classification, it is noted that the infection classification "Excludes:... infective dermatitis...". See the WHO classification, op. cit. although skin infections can result in skin inflammation.Skin inflammation due to skin infection is called "infective dermatitis". See the WHO classifications, op. cit.
Causes
=Bacterial=
{{main|Skin and skin structure infection}}
{{further|List of cutaneous conditions#Bacterium-related}}
- 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.{{cite journal | vauthors = Breyre A, Frazee BW | title = Skin and Soft Tissue Infections in the Emergency Department | journal = Emergency Medicine Clinics of North America | volume = 36 | issue = 4 | pages = 723–750 | date = November 2018 | pmid = 30297001 | doi = 10.1016/j.emc.2018.06.005 | s2cid = 52942182 }} Purulent cellulitis is often caused by Staphylococcus aureus, including both methicillin-sensitive (MSSA) and methicillin-resistant S. aureus (MRSA).{{cite journal | vauthors = Raff AB, Kroshinsky D | title = Cellulitis: A Review | journal = JAMA | volume = 316 | issue = 3 | pages = 325–337 | date = July 2016 | pmid = 27434444 | doi = 10.1001/jama.2016.8825 | s2cid = 241077983 }} 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.{{cite journal | vauthors = Chen LL, Fasolka B, Treacy C | title = Necrotizing fasciitis: A comprehensive review | journal = Nursing | volume = 50 | issue = 9 | pages = 34–40 | date = September 2020 | pmid = 32826674 | pmc = 8828282 | doi = 10.1097/01.NURSE.0000694752.85118.62 }}
- Erysipelas, a bacterial infection which primarily affects superficial dermis, and often involves superficial lymphatics.{{cite journal | vauthors = Clebak KT, Malone MA | title = Skin Infections | journal = Primary Care | volume = 45 | issue = 3 | pages = 433–454 | date = September 2018 | pmid = 30115333 | doi = 10.1016/j.pop.2018.05.004 | series = Infectious Disease | s2cid = 52022225 }} Unlike cellulitis, it does not affect 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, 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.{{cite book | vauthors = Winters R, Mitchell M | chapter = Folliculitis|date=2021| chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK547754/| title = StatPearls|place=Treasure Island (FL)|publisher=StatPearls Publishing|pmid=31613534|access-date=2021-12-03 }} Other causative agents of folliculitis include fungi (most commonly Malassezia species), viruses (such as herpes simplex virus), and mites (Demodex species).{{cite journal | vauthors = Henning MA, Jemec GB, Saunte DM | title = [Malassezia folliculitis] | journal = Ugeskrift for Laeger | volume = 182 | issue = 47 | pages = V08200572 | date = November 2020 | pmid = 33215579 | url = https://pubmed.ncbi.nlm.nih.gov/33215579 }}
- 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.{{cite web|url=https://www.nhs.uk/conditions/impetigo/|title=Impetigo|date=October 19, 2017|website=nhs.uk}}{{cite book| vauthors = Kumar V, Abbas AK, Fausto N, Mitchell RN | year = 2007 | title = Robbins Basic Pathology | edition = 8th | publisher = Saunders Elsevier | page = 843 | isbn = 978-1-4160-2973-1}} Impetigo has a characteristic appearance with yellow (honey-coloured), crusted lesions occurring around mouth, nose, and chin.{{cite journal | vauthors = Johnson MK | title = Impetigo | journal = Advanced Emergency Nursing Journal | volume = 42 | issue = 4 | pages = 262–269 | date = 2020 | pmid = 33105179 | doi = 10.1097/TME.0000000000000320 | s2cid = 225081229 }} It is estimated, that at any given time, it affects 140 million people globally. Impetigo can be further classified into bullous and nonbullous forms.{{cite journal | vauthors = Dollani LC, Marathe KS | title = Impetigo/Staphylococcal Scalded Skin Disease | journal = Pediatrics in Review | volume = 41 | issue = 4 | pages = 210–212 | date = April 2020 | pmid = 32238552 | doi = 10.1542/pir.2018-0206 | s2cid = 214768670 }} 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. {{cite journal | vauthors = Brazel M, Desai A, Are A, Motaparthi K | title = Staphylococcal Scalded Skin Syndrome and Bullous Impetigo | journal = Medicina | volume = 57 | issue = 11 | pages = 1157 | date = October 2021 | pmid = 34833375 | pmc = 8623226 | doi = 10.3390/medicina57111157 | doi-access = free }} In rare instances, bullous impetigo can spread and lead to Staphylococcal Scalded Skin Syndrome (SSSS), a potentially life-threatening infection.
=Fungal=
{{further|List of cutaneous conditions#Mycosis-related}}
Fungal skin infections, sometimes referred to as dermatomycoses, 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.{{cite journal | vauthors = Verma P, Jha A | title = Mycetoma: reviewing a neglected disease | journal = Clinical and Experimental Dermatology | volume = 44 | issue = 2 | pages = 123–129 | date = March 2019 | pmid = 29808607 | doi = 10.1111/ced.13642 | s2cid = 44123860 | doi-access = free }} If not treated appropriately and in a timely fashion mycetoma infections can extend to deeper tissues like bones and joints causing osteomyelitis.{{cite journal | vauthors = El-Sobky TA, Haleem JF, Samir S | title = Eumycetoma Osteomyelitis of the Calcaneus in a Child: A Radiologic-Pathologic Correlation following Total Calcanectomy | journal = Case Reports in Pathology | volume = 2015 | pages = 129020 | date = 21 September 2015 | pmid = 26483983 | pmc = 4592886 | doi = 10.1155/2015/129020 | s2cid = 15644051 | doi-access = free }} Extensive osteomyelitis can necessitate surgical bone resections and even lower limb amputation.
As of 2010, they affect about one billion people globally.{{cite journal | vauthors = Vos T, Flaxman AD, Naghavi M, Lozano R, Michaud C, Ezzati M, etal | title = 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 | journal = Lancet | volume = 380 | issue = 9859 | pages = 2163–2196 | date = December 2012 | pmid = 23245607 | pmc = 6350784 | doi = 10.1016/S0140-6736(12)61729-2 | collaboration = }} 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.{{cite journal | vauthors = Jartarkar SR, Patil A, Goldust Y, Cockerell CJ, Schwartz RA, Grabbe S, Goldust M | title = Pathogenesis, Immunology and Management of Dermatophytosis | journal = Journal of Fungi | volume = 8 | issue = 1 | pages = 39 | date = December 2021 | pmid = 35049979 | pmc = 8781719 | doi = 10.3390/jof8010039 | doi-access = free }} 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 affected by superficial fungal infections, with dermatophytosis predominating.{{cite journal | vauthors = Begum J, Mir NA, Lingaraju MC, Buyamayum B, Dev K | title = Recent advances in the diagnosis of dermatophytosis | journal = Journal of Basic Microbiology | volume = 60 | issue = 4 | pages = 293–303 | date = April 2020 | pmid = 32003043 | doi = 10.1002/jobm.201900675 | s2cid = 210983216 }}
- Oral candidiasis, also commonly referred to as oral thrush, is a fungal infection caused mainly by Candida albicans, which affects mucosal membranes of the oral cavity and the tongue.{{cite journal | vauthors = Vila T, Sultan AS, Montelongo-Jauregui D, Jabra-Rizk MA | title = Oral Candidiasis: A Disease of Opportunity | journal = Journal of Fungi | volume = 6 | issue = 1 | pages = 15 | date = January 2020 | pmid = 31963180 | pmc = 7151112 | doi = 10.3390/jof6010015 | doi-access = free }} 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.{{cite journal | vauthors = Quindós G, Gil-Alonso S, Marcos-Arias C, Sevillano E, Mateo E, Jauregizar N, Eraso E | title = Therapeutic tools for oral candidiasis: Current and new antifungal drugs | journal = Medicina Oral, Patologia Oral y Cirugia Bucal | volume = 24 | issue = 2 | pages = e172–e180 | date = March 2019 | pmid = 30818309 | pmc = 6441600 | doi = 10.4317/medoral.22978 }} It is estimated that oral candidiasis affects approximately 2 million people every year worldwide.{{cite journal | vauthors = Bongomin F, Gago S, Oladele RO, Denning DW | title = Global and Multi-National Prevalence of Fungal Diseases-Estimate Precision | journal = Journal of Fungi | volume = 3 | issue = 4 | pages = 57 | date = October 2017 | pmid = 29371573 | pmc = 5753159 | doi = 10.3390/jof3040057 | doi-access = free }}
- Onychomycosis, a fungal infection which predominantly affects toenails.{{cite journal | vauthors = Leung AK, Lam JM, Leong KF, Hon KL, Barankin B, Leung AA, Wong AH | title = Onychomycosis: An Updated Review | journal = Recent Patents on Inflammation & Allergy Drug Discovery | volume = 14 | issue = 1 | pages = 32–45 | date = 2020 | pmid = 31738146 | pmc = 7509699 | doi = 10.2174/1872213X13666191026090713 }} 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.{{cite journal | vauthors = Gupta AK, Stec N, Summerbell RC, Shear NH, Piguet V, Tosti A, Piraccini BM | title = Onychomycosis: a review | journal = Journal of the European Academy of Dermatology and Venereology | volume = 34 | issue = 9 | pages = 1972–1990 | date = September 2020 | pmid = 32239567 | doi = 10.1111/jdv.16394 | s2cid = 214768942 | hdl = 11585/871129 | hdl-access = free }} Estimated prevalence of onychomycosis in North America is between 8.7% to 13.8%.
=Parasitic=
{{further|List of cutaneous conditions#Parasitic infestations, stings, and bites}}
Parasitic infestations of the skin are caused by several phyla of organisms, including Annelida, Arthropoda, Bryozoa, Chordata, Cnidaria, Cyanobacteria, Echinodermata, Nemathelminthes, Platyhelminthes, and Protozoa.{{cite journal | vauthors = Diaz JH | title = Mite-transmitted dermatoses and infectious diseases in returning travelers | journal = Journal of Travel Medicine | volume = 17 | issue = 1 | pages = 21–31 | date = January 2010 | pmid = 20074098 | doi = 10.1111/j.1708-8305.2009.00352.x | doi-access = free }}
=Viral=
{{further|List of cutaneous conditions#Virus-related}}
Virus-related cutaneous conditions caused by these obligate intracellular agents derive from both DNA and RNA viruses.{{cite journal | vauthors = Lebwohl MG, Rosen T, Stockfleth E | title = The role of human papillomavirus in common skin conditions: current viewpoints and therapeutic options | journal = Cutis | volume = 86 | issue = 5 | pages = suppl 1–11; quiz suppl 12 | date = November 2010 | pmid = 21214125 | author-link = Mark G. Lebwohl }} Some examples of viral skin infections include:
- Warts, benign proliferative skin lesions that are caused by human papilloma virus (HPV).{{cite journal | vauthors = Mulhem E, Pinelis S | title = Treatment of nongenital cutaneous warts | journal = American Family Physician | volume = 84 | issue = 3 | pages = 288–293 | date = August 2011 | pmid = 21842775 | url = https://www.aafp.org/afp/2011/0801/p288.html }}{{cite journal | vauthors = Soenjoyo KR, Chua BW, Wee LW, Koh MJ, Ang SB | title = Treatment of cutaneous viral warts in children: A review | journal = Dermatologic Therapy | volume = 33 | issue = 6 | pages = e14034 | date = November 2020 | pmid = 32683782 | doi = 10.1111/dth.14034 | s2cid = 220655257 | doi-access = free }} 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.{{cite journal | vauthors = Witchey DJ, Witchey NB, Roth-Kauffman MM, Kauffman MK | title = Plantar Warts: Epidemiology, Pathophysiology, and Clinical Management | journal = The Journal of the American Osteopathic Association | volume = 118 | issue = 2 | pages = 92–105 | date = February 2018 | pmid = 29379975 | doi = 10.7556/jaoa.2018.024 | s2cid = 25371618 | doi-access = free }} 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).{{cite journal | vauthors = Freer G, Pistello M | title = Varicella-zoster virus infection: natural history, clinical manifestations, immunity and current and future vaccination strategies | journal = The New Microbiologica | volume = 41 | issue = 2 | pages = 95–105 | date = April 2018 | pmid = 29498740 | url = https://pubmed.ncbi.nlm.nih.gov/29498740 }} It is characterized by pruritic blister-like rash which may cover entire body, affecting all age groups.{{Cite web |date=2022-03-23 |title=About Chickenpox {{!}} CDC |url=https://www.cdc.gov/chickenpox/about/index.html |access-date=2022-04-24 |website=www.cdc.gov |language=en-us}} 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.{{cite journal | vauthors = Wutzler P, Bonanni P, Burgess M, Gershon A, Sáfadi MA, Casabona G | title = Varicella vaccination - the global experience | journal = Expert Review of Vaccines | volume = 16 | issue = 8 | pages = 833–843 | date = August 2017 | pmid = 28644696 | pmc = 5739310 | doi = 10.1080/14760584.2017.1343669 }}
- 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.{{cite journal | vauthors = Esposito S, Principi N | title = Hand, foot and mouth disease: current knowledge on clinical manifestations, epidemiology, aetiology and prevention | journal = European Journal of Clinical Microbiology & Infectious Diseases | volume = 37 | issue = 3 | pages = 391–398 | date = March 2018 | pmid = 29411190 | doi = 10.1007/s10096-018-3206-x | s2cid = 3376169 }} It is characterized by low grade fever and maculopapular rash on palms of the hands, soles of the feet, and around mouth.{{cite journal | vauthors = Saguil A, Kane SF, Lauters R, Mercado MG | title = Hand-Foot-and-Mouth Disease: Rapid Evidence Review | journal = American Family Physician | volume = 100 | issue = 7 | pages = 408–414 | date = October 2019 | pmid = 31573162 | url = https://pubmed.ncbi.nlm.nih.gov/31573162 }} It is caused by the human enteroviruses and coxsackieviruses, a positive-sense single-stranded RNA viruses.
References
{{reflist}}
{{Diseases of the skin and appendages by morphology}}