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Impetigo is a
bacterial infection Pathogenic bacteria are bacteria that can cause disease. This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and are often beneficial but others can cause infectious diseases. The number ...
that involves the superficial
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...
. The most common presentation is yellowish crusts on the face, arms, or legs. Less commonly there may be large blisters which affect the
groin In human anatomy, the groin (the adjective is ''inguinal'', as in inguinal canal) is the junctional area (also known as the inguinal region) between the abdomen and the thigh on either side of the pubic bone. This is also known as the medial comp ...
or
armpits The axilla (also, armpit, underarm or oxter) is the area on the human body directly under the shoulder joint. It includes the axillary space, an anatomical space within the shoulder girdle between the arm and the thoracic cage, bounded superio ...
. The lesions may be painful or itchy.
Fever Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single ...
is uncommon. It is typically due to either ''
Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive ...
'' or ''
Streptococcus pyogenes ''Streptococcus pyogenes'' is a species of Gram-positive, aerotolerant bacteria in the genus ''Streptococcus''. These bacteria are extracellular, and made up of non-motile and non-sporing cocci (round cells) that tend to link in chains. They are ...
''. Risk factors include attending
day care Child care, otherwise known as day care, is the care and supervision of a child or multiple children at a time, whose ages range from two weeks of age to 18 years. Although most parents spend a significant amount of time caring for their child(r ...
, crowding, poor nutrition,
diabetes mellitus Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
,
contact sport Contact sports are sports that emphasize or require physical contact between players. Some sports, such as mixed martial arts, are scored on impacting an opponent, while others, including rugby football, gridiron football and Australian rules fo ...
s, and breaks in the skin such as from
mosquito bite Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning "gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "lit ...
s,
eczema Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can ...
, scabies, or
herpes Herpes simplex is a viral infection caused by the herpes simplex virus. Infections are categorized based on the part of the body infected. Oral herpes involves the face or mouth. It may result in small blisters in groups often called cold ...
. With contact it can spread around or between people. Diagnosis is typically based on the symptoms and appearance. Prevention is by
hand washing Hand washing (or handwashing), also known as hand hygiene, is the act of cleaning one's hands with soap or handwash and water to remove viruses/bacteria/microorganisms, dirt, grease, or other harmful and unwanted substances stuck to the hands ...
, avoiding people who are infected, and cleaning injuries. Treatment is typically with
antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
creams such as
mupirocin Mupirocin, sold under the brand name Bactroban among others, is a topical antibiotic useful against superficial skin infections such as impetigo or folliculitis. It may also be used to get rid of methicillin-resistant ''S. aureus'' (MRSA) wh ...
or fusidic acid. Antibiotics by mouth, such as
cefalexin Cefalexin, also spelled cephalexin, is an antibiotic that can treat a number of bacterial infections. It kills gram-positive and some gram-negative bacteria by disrupting the growth of the bacterial cell wall. Cefalexin is a beta-lactam antibi ...
, may be used if large areas are affected.
Antibiotic-resistant Antimicrobial resistance (AMR) occurs when microbes evolve mechanisms that protect them from the effects of antimicrobials. All classes of microbes can evolve resistance. Fungi evolve antifungal resistance. Viruses evolve antiviral resistance. ...
forms have been found. Impetigo affected about 140 million people (2% of the world population) in 2010. It can occur at any age, but is most common in young children. In some places the condition is also known as "school sores". Without treatment people typically get better within three weeks. Recurring infections can occur due to colonization of the nose by the bacteria. Complications may include
cellulitis Cellulitis is usually a bacterial infection involving the inner layers of the skin. It specifically affects the dermis and subcutaneous fat. Signs and symptoms include an area of redness which increases in size over a few days. The borders of ...
or
poststreptococcal glomerulonephritis Acute proliferative glomerulonephritis is a disorder of the glomerulus, small blood vessels of the kidney. It is a common complication of bacterial infections, typically skin infection by ''Streptococcus'' bacteria types 12, 4 and 1 (impetigo) bu ...
. The name is from the
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
''impetere'' meaning "attack".


Signs and symptoms


Contagious impetigo

This most common form of impetigo, also called nonbullous impetigo, most often begins as a red sore near the nose or mouth which soon breaks, leaking
pus Pus is an exudate, typically white-yellow, yellow, or yellow-brown, formed at the site of inflammation during bacterial or fungal infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collection ...
or fluid, and forms a honey-colored scab, followed by a red mark which often heals without leaving a scar. Sores are not painful, but they may be itchy. Lymph nodes in the affected area may be swollen, but fever is rare. Touching or scratching the sores may easily spread the infection to other parts of the body.
Skin ulcers An ulcer is a sore on the skin or a mucous membrane, accompanied by the disintegration of tissue. Ulcers can result in complete loss of the epidermis and often portions of the dermis and even subcutaneous fat. Ulcers are most common on the skin ...
with redness and scarring also may result from scratching or abrading the skin.


Bullous impetigo

Bullous impetigo, mainly seen in children younger than 2 years, involves painless, fluid-filled blisters, mostly on the arms, legs, and trunk, surrounded by red and itchy (but not sore) skin. The blisters may be large or small. After they break, they form yellow scabs.


Ecthyma

Ecthyma Ecthyma( ec·​thy·​ma , \ ek-ˈthī-mə )is a variation of impetigo, presenting at a deeper level of tissue. It is usually associated with Group A (beta-hemolytic) Streptococcus (abbreviated GAS). See also * Ecthyma gangrenosum Ecthyma ...
, the nonbullous form of impetigo, produces painful fluid- or pus-filled sores with redness of skin, usually on the arms and legs, become
ulcers An ulcer is a discontinuity or break in a bodily membrane that impedes normal function of the affected organ. According to Robbins's pathology, "ulcer is the breach of the continuity of skin, epithelium or mucous membrane caused by sloughing o ...
that penetrate deeper into the dermis. After they break open, they form hard, thick, gray-yellow scabs, which sometimes leave scars. Ecthyma may be accompanied by swollen lymph nodes in the affected area.


Causes

Impetigo is primarily caused by ''
Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive ...
'', and sometimes by ''
Streptococcus pyogenes ''Streptococcus pyogenes'' is a species of Gram-positive, aerotolerant bacteria in the genus ''Streptococcus''. These bacteria are extracellular, and made up of non-motile and non-sporing cocci (round cells) that tend to link in chains. They are ...
''. Both
bullous A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of this ...
and nonbullous are primarily caused by ''S. aureus'', with ''Streptococcus ''also commonly being involved in the nonbullous form.


Predisposing factors

Impetigo is more likely to infect children ages 2–5, especially those that attend school or day care. 70% of cases are the nonbullous form and 30% are the bullous form. Other factors can increase the risk of contracting impetigo such as diabetes mellitus, dermatitis, immunodeficiency disorders, and other irritable skin disorders. Impetigo occurs more frequently among people who live in warm climates.


Transmission

The
infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dis ...
is spread by direct contact with
lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals. Types There is no designated classif ...
s or with nasal carriers. The
incubation period Incubation period (also known as the latent period or latency period) is the time elapsed between exposure to a pathogenic organism, a chemical, or radiation, and when symptoms and signs are first apparent. In a typical infectious disease, the in ...
is 1–3 days after exposure to ''Streptococcus'' and 4–10 days for ''Staphylococcus''. Dried streptococci in the air are not infectious to intact skin. Scratching may spread the lesions.


Diagnosis

Impetigo is usually diagnosed based on its appearance. It generally appears as honey-colored scabs formed from dried serum and is often found on the arms, legs, or face. If a visual diagnosis is unclear a culture may be done to test for resistant bacteria.


Differential diagnosis

Other conditions that can result in symptoms similar to the common form include
contact dermatitis Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes are ...
, herpes simplex virus,
discoid lupus Discoid lupus erythematosus is the most common type of chronic cutaneous lupus (CCLE), an Autoimmune disease, autoimmune skin condition on the lupus erythematosus spectrum of illnesses. It presents with red, painful, inflamed and coin-shaped patch ...
, and scabies. Other conditions that can result in symptoms similar to the blistering form include other
bullous A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of this ...
skin diseases,
burn A burn is an injury to skin, or other tissues, caused by heat, cold, electricity, chemicals, friction, or ultraviolet radiation (like sunburn). Most burns are due to heat from hot liquids (called scalding), solids, or fire. Burns occur mainl ...
s, and
necrotizing fasciitis Necrotizing fasciitis (NF), also known as flesh-eating disease, is a bacterial infection that results in the death of parts of the body's soft tissue. It is a severe disease of sudden onset that spreads rapidly. Symptoms usually include red or p ...
.


Prevention

To prevent the spread of impetigo the skin and any open wounds should be kept clean and covered. Care should be taken to keep fluids from an infected person away from the skin of a non-infected person. Washing hands, linens, and affected areas will lower the likelihood of contact with infected fluids. Scratching can spread the sores; keeping nails short will reduce the chances of spreading. Infected people should avoid contact with others and eliminate sharing of clothing or linens. Children with impetigo can return to school 24 hours after starting antibiotic therapy as long as their draining lesions are covered.


Treatment

Antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
s, either as a cream or by mouth, are usually prescribed. Mild cases may be treated with
mupirocin Mupirocin, sold under the brand name Bactroban among others, is a topical antibiotic useful against superficial skin infections such as impetigo or folliculitis. It may also be used to get rid of methicillin-resistant ''S. aureus'' (MRSA) wh ...
ointments. In 95% of cases, a single 7-day antibiotic course results in resolution in children. It has been advocated that topical
antiseptic An antiseptic (from Greek ἀντί ''anti'', "against" and σηπτικός ''sēptikos'', "putrefactive") is an antimicrobial substance or compound that is applied to living tissue/skin to reduce the possibility of infection, sepsis, or putre ...
s are inferior to topical antibiotics, and therefore should not be used as a replacement. However, the
National Institute for Health and Care Excellence The National Institute for Health and Care Excellence (NICE) is an executive non-departmental public body of the Department of Health and Social Care in England that publishes guidelines in four areas: * the use of health technologies withi ...
(NICE) as of February 2020 recommends a hydrogen peroxide 1% cream antiseptic rather than topical antibiotics for localised non-bullous impetigo in otherwise well individuals. This recommendation is part of an effort to reduce the overuse of antimicrobials that may contribute to the development of resistant organisms such as
MRSA Methicillin-resistant ''Staphylococcus aureus'' (MRSA) is a group of Gram-positive bacteria that are genetically distinct from other strains of ''Staphylococcus aureus''. MRSA is responsible for several difficult-to-treat infections in humans. ...
. More severe cases require oral antibiotics, such as
dicloxacillin Dicloxacillin is a narrow-spectrum β-lactam antibiotic of the penicillin class. It is used to treat infections caused by susceptible (non-resistant) Gram-positive bacteria.Product Information: DICLOXACILLIN SODIUM-dicloxacillin sodium capsule. T ...
,
flucloxacillin Flucloxacillin, also known as floxacillin, is an antibiotic used to treat skin infections, external ear infections, infections of leg ulcers, diabetic foot infections, and infection of bone. It may be used together with other medications to t ...
, or
erythromycin Erythromycin is an antibiotic used for the treatment of a number of bacterial infections. This includes respiratory tract infections, skin infections, chlamydia infections, pelvic inflammatory disease, and syphilis. It may also be used duri ...
. Alternatively,
amoxicillin Amoxicillin is an antibiotic medication used to treat a number of bacterial infections. These include middle ear infection, strep throat, pneumonia, skin infections, and urinary tract infections among others. It is taken by mouth, or less c ...
combined with clavulanate potassium, cephalosporins (first-generation) and many others may also be used as an antibiotic treatment. Alternatives for people who are seriously allergic to penicillin or infections with methicillin-resistant ''Staphococcus aureus'' include
doxycycline Doxycycline is a broad-spectrum tetracycline class antibiotic used in the treatment of infections caused by bacteria and certain parasites. It is used to treat bacterial pneumonia, acne, chlamydia infections, Lyme disease, cholera, typhus, an ...
,
clindamycin Clindamycin is an antibiotic medication used for the treatment of a number of bacterial infections, including osteomyelitis (bone) or joint infections, pelvic inflammatory disease, strep throat, pneumonia, acute otitis media (middle ear infec ...
, and trimethoprim-sulphamethoxazole, although doxycycline should not be used in children under the age of eight years old due to the risk of drug-induced tooth discolouration. When streptococci alone are the cause, penicillin is the drug of choice. When the condition presents with
ulcer An ulcer is a discontinuity or break in a bodily membrane that impedes normal function of the affected organ. According to Robbins's pathology, "ulcer is the breach of the continuity of skin, epithelium or mucous membrane caused by sloughing o ...
s,
valacyclovir Valaciclovir, also spelled valacyclovir, is an antiviral medication used to treat outbreaks of herpes simplex or herpes zoster (shingles). It is also used to prevent cytomegalovirus following a kidney transplant in high risk cases. It is taken ...
, an antiviral, may be given in case a viral infection is causing the ulcer.


Alternative medicine

There is not enough evidence to recommend alternative medicine such as
tea tree oil Tea tree oil, also known as melaleuca oil, is an essential oil with a fresh camphoraceous odor and a colour that ranges from pale yellow to nearly colourless and clear. It is derived from the leaves of the tea tree, '' Melaleuca alternifolia'', ...
or
honey Honey is a sweet and viscous substance made by several bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primar ...
.


Prognosis

Without treatment, individuals with impetigo typically get better within three weeks. Complications may include
cellulitis Cellulitis is usually a bacterial infection involving the inner layers of the skin. It specifically affects the dermis and subcutaneous fat. Signs and symptoms include an area of redness which increases in size over a few days. The borders of ...
or
poststreptococcal glomerulonephritis Acute proliferative glomerulonephritis is a disorder of the glomerulus, small blood vessels of the kidney. It is a common complication of bacterial infections, typically skin infection by ''Streptococcus'' bacteria types 12, 4 and 1 (impetigo) bu ...
. Rheumatic fever does not appear to be related.


Epidemiology

Globally, impetigo affects more than 162 million children in low- to middle-income countries. The rates are highest in countries with low available resources and is especially prevalent in the region of
Oceania Oceania (, , ) is a region, geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern Hemisphere, Eastern and Western Hemisphere, Western hemispheres, Oceania is estimated to have a land area of ...
. The
tropical climate Tropical climate is the first of the five major climate groups in the Köppen climate classification identified with the letter A. Tropical climates are defined by a monthly average temperature of 18 °C (64.4 °F) or higher in the cool ...
and high population in lower socioeconomic regions contribute to these high rates. Children under the age of 4 in the United Kingdom are 2.8% more likely than average to contract impetigo; this decreases to 1.6% for children up to 15 years old. As age increases, the rate of impetigo declines, but all ages are still susceptible.


History

Impetigo was originally described and differentiated by
William Tilbury Fox William Tilbury Fox, MD, FRCP (1836 – 7 June 1879) was an English dermatologist. He was born in Broughton, Hampshire the son of physician Luther Owen Fox and Mary (née Tilbury) Fox, and the brother of Thomas Colcott Fox, also a derma ...
around 1864. The word ''impetigo'' is the generic
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
word for 'skin eruption', and it stems from the verb ''impetere'' 'to attack' (as in ''impetus''). Before the discovery of antibiotics, the disease was treated with an application of the antiseptic
gentian violet Crystal violet or gentian violet, also known as methyl violet 10B or hexamethyl pararosaniline chloride, is a triarylmethane dye used as a histological stain and in Gram's method of classifying bacteria. Crystal violet has antibacterial, antif ...
, which was an effective treatment.


References


External links

* * {{Bacterial cutaneous infections Bacterium-related cutaneous conditions Pediatrics Wikipedia medicine articles ready to translate Wikipedia emergency medicine articles ready to translate