Skin and soft tissue infections are disorders involving the layers of the skin and the soft tissues directly beneath it.
Skin and soft tissue infections are infections involving the layers of the skin and the soft tissues directly beneath it, generally caused by viruses, bacteria, or fungi that have entered the body through a cut, scrape, bite or other wound.
Viruses * , bacteria * , and fungi * generally cause skin and soft tissue infections by entering the body at a spot where a cut, scrape, bite, or other wound has broken the skin. Some infections are the result of bacteria that normally live on the body. These infections can affect the layers of the skin or deeper tissues such as muscle and connective tissue (the interlacing framework of tissue that forms ligaments * , tendons * , and other supporting structures of the body), and they may bring about symptoms in other parts of the body.
Many infections like chickenpox (varicella) and measles (rubeola) affect the skin, but these infections involve the whole body and do not arise primarily within the skin or soft tissues.
Tinea versicolor, or pityriasis (pih-tih-RYE-uh-sis) versicolor, is caused by the fungus Malassezia furfur. Symptoms include scaly patches of skin, ranging in color from light to dark. The patches occur on the chest, neck, back, underarms, and upper arms. Hot humid weather encourages the growth of tinea versicolor.
Impetigo (im-pih-TEE-go) is a skin infection in which red blister-like bumps develop that contain a yellowish fluid or pus * . After the blisters break open, they crust over. Impetigo is most common on the face, especially around the nose and mouth. Usually, either Streptococcus (strep-tuh-KAH-kus) or Staphylococcus (stah-fih-lo-KAH-kus) bacteria are the cause of the infection.
Skin abscesses (AB-seh-sez) may occur in areas of the skin where the body has been fighting a bacterial infection. To isolate the infection, the body forms a wall of tissue around the collection of pus, and this area is the abscess. Abscesses are usually round, raised, and red, and they may feel warm and tender. A furuncle (FYOOR-ung-kul), or boil, is an abscess that forms at the base of a hair follicle * . A carbuncle (KAR-bung-kul) forms when the infection spreads to include several follicles and the surrounding skin and deeper tissues. Like furuncles, carbuncles are red, raised, and painful to the touch.
Cellulitis (sel-yoo-LYE-tis) is an inflammation of the skin and/or the tissues beneath it. The culprits behind the infection are almost always group A Streptococcus or Staphylococcus aureus (stah-fih-lo-KAH-kus ARE-ree-us) bacteria. Cellulitis may occur in people with diabetes *
Antibiotics are used to treat cellulitis. Even after the infection is gone, the skin may look different for several weeks. Complications are rare, but they can include sepsis * , gangrene * , and lymphangitis * . Cellulitis may involve infection of deeper tissue called fascia (FAY-she-uh). Infection in this layer can be very serious or even life-threatening, and often requires surgery to remove the infected tissue.
Any type of bite that breaks the skin (cat, dog, wild animal, human) puts an individual at very high risk of skin and soft tissue infection. Dog bites tend to be particularly damaging to the skin and underlying tissues and muscle, but cat bites and human bites have a higher rate of infection, usually occurring several days after the actual biting incident. Signs of infection include redness, swelling, warmth of the skin overlying and surrounding the wound, as well as pain, and pus oozing from the wound. These signs can develop within several hours following a cat bite, much faster than the usual one or two days. Rodent bites and the bites of wild animals (especially raccoons, skunks, bats, and foxes) or domestic animals of unknown rabies * status put the bite victim at high risk of contracting the potentially fatal viral infection called rabies. In most instances, when the rabies status of the biting animal cannot be confirmed, the individual is given a series of six shots to prevent the development of this life-threatening infection. A tetanus booster shot is also given to people who suffer an animal or human bite, and who have not had a tetanus booster within the previous five years. Moreover, human bites put the recipient at risk of contracting other infections such as HIV * or hepatitis * .
While the Staphylococcus bacterium has long been implicated in skin and soft tissue infections, a later strain that is resistant to methicillin and other antibiotics exists. Whereas in the past this type of infection tended to affect only already-ill, hospitalized patients, a later form, called community-associated methicillin-resistant Staphylococcus aureus (MRSA), is of particular concern because it may be more contagious via contact between previously healthy individuals than other forms of Staphylococcus (staph) infections. People who have close physical contact are vulnerable to this type of infection. This category includes children in day care or other crowded school settings, people participating in contact sports, prisoners, military personnel, homeless people, homosexual men, and users of illegal intravenous * (IV) drugs.
Molluscum contagiosum (moh-LUSkum kon-tay-jee-O-sum), caused by a virus, produces small solid domeshaped bumps on the surface of the skin. They are flesh-colored and pearly with a dimple in the center. The growths are similar to warts. Viruses cause both conditions: poxvirus in the case of molluscum contagiosum and human papillomavirus in the case of warts. Growths can be single, but they most often appear in groups on the trunk, arms, legs, and genitals * , and occasionally on the face.
There are two types of the herpes simplex virus (HSV): HSV-1 and HSV-2. Both can show up as skin infections. HSV-1 can cause small clear blisters (also known as cold sores, fever blisters, or oral herpes) around the lips on the face, and HSV-2 can cause similar-looking blisters in the genital area. These blisters break, form ulcers, and then crust over. When the crust falls off, red spots of healing skin are seen.
Warts are caused by human papillomavirus (pah-pih-LOmahvy-rus), or HPV. They can be skin-colored, pink, tan, or white, and they may appear anywhere on the body. Common warts usually are seen on the hands (especially around the nails), feet, and face, because the virus spreads most easily to those areas. Common warts are rough and raised, but plantar warts, found on the soles of the feet, are flat. Unlike other warts, plantar warts can be painful.
Necrotizing fasciitis, cellulitis, and abscesses are not contagious from person to person, but the bacteria that can cause these infections can spread between people. Dermatophytes, warts, and molluscum contagiosum spread fairly easily through skin-to-skin contact. Impetigo can spread easily, especially among children who may scratch the lesions and then touch other areas of their skin or another person. People can also contract impetigo from handling clothing or blankets that have been in contact with infected skin.
Fungal skin infections typically are treated with antifungal creams or ointments. In severe cases or when the infections do not improve with this therapy, several antifungal medications * are available that may be given by mouth.
Doctors prescribe antibiotics to treat impetigo. The infection generally clears without leaving permanent skin damage.
Most skin abscesses eventually burst to allow the pus to drain, but treatment with antibiotics may be needed to clear up the infection in some cases. When a skin abscess does not improve on its own, it likely needs to be lanced (punctured and drained) by a doctor.
Many warts disappear by themselves after months or even years. Treatments are available for those that do not, including over-the-counter medications or professional treatment by freezing, surgery, laser therapy, or acid creams.
Because of the unusual destructiveness and virulence of MRSA, it is important to maintain a high level of suspicion when an infection does not respond immediately to treatment or when an infection spreads unusually rapidly. Infections caused by this type of bacteria will not respond to the usual antibiotics, although there are some oral antibiotics that can be effective. More severe infections require IV antibiotics. In some severe cases, a wide excision of all infected tissue is required in order to rid the body of the organism and lower the risk of systemic spread of this virulent organism. For necrotizing facitiis, early treatment with antibiotics and surgery to remove the damaged tissue is extremely important. Recovery may take several months.
Molluscum contagiosum usually clears up by itself over several months, although new growths may arise on the skin if the virus spreads through contact with infected areas. Doctors may recommend home treatment with over-the-counter medications or removal of the growths by freezing, surgery, laser therapy, or acid treatments.
As of 2016, there was no cure for either HSV-1 or HSV-2. Antiviral medications can help control outbreaks of herpes virus and are used to treat genital herpes or sometimes recurrent cold sores from HSV-1.
See also Abscesses • Bacterial Infections • Diabetes • Fungal Infections • Gangrene • Herpes Simplex Virus Infections • Impetigo • Rabies • Ringworm • Sepsis • Skin Conditions: Overview • Skin Parasites: Overview • Staphylococcal Infections • Streptococcal Infections • Warts • Wounds • Zoonoses: Overview
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* viruses (VY-rus-sez) are tiny infectious agents that can cause diseases. A virus can reproduce only within the cells it infects.
* bacteria (bak-TEER-ee-a) are single-celled microorganisms, which typically reproduce by cell division. Some but not all types of bacteria can cause disease in humans. Many types can live in the body without causing harm.
* fungi (FUNG-eye) are microorganisms that can grow in or on the body, causing infections of internal organs or of the skin, hair, and nails.
* ligaments (LIG-a-ments) are bands of fibrous tissue that connect bones or cartilage, supporting and strengthening the joints. Ligaments in the mouth hold the roots of teeth in the tooth sockets.
* tendon (TEN-dun) is a fibrous cord of connective tissue that attaches a muscle to a bone or other structure.
* pus is a thick, creamy fluid, usually yellow or ivory in color, that forms at the site of an infection. Pus contains infection-fighting white cells and other substances.
* hair follicle (FAH-lih-kul) is the skin structure from which hair develops and grows.
* diabetes (dye-uh-BEE-teez) is a condition in which the body's pancreas does not produce enough insulin or the body cannot use the insulin it makes effectively, resulting in increased levels of sugar in the blood.
* sepsis is a potentially serious spreading of infection, usually bacterial, through the bloodstream and body.
* gangrene (GANG-green) is the decay or death of living tissue caused by a lack of oxygen supply to the tissue and/or bacterial infection of the tissue.
* lymphangitis (lim-fan-JIE-tis) is inflammation of the lymphatic system, the system that carries lymph through the body. Lymph is a clear fluid that contains white blood cells.
* rabies (RAY-beez) is a viral infection of the central nervous system that usually is transmitted to humans by the bite of an infected animal.
* HIV, or human immunodeficiency virus (HYOO-mun ih-myoono-dih-FIH-shen-see), is the virus that causes AIDS (acquired immunodeficiency syndrome).
* hepatitis (heh-puh-TIE-tis) is an inflammation of the liver. Hepatitis can be caused by viruses, bacteria, and a number of other non-infectious medical conditions.
* intravenous (in-tra-VEE-nus), or IV, means within or through a vein. For example, medications, fluid, or other substances can be given through a needle or soft tube inserted through the skin's surface directly into a vein.
* genitals (JEH-nih-tuls) are the external sexual organs.
* ultraviolet light is a wavelength of light beyond visible light. On the spectrum of light, it falls between the violet end of visible light and x-rays.
* antifungal medications are drugs used to treat fungal infections.