furuncle

What is furuncle

Furuncle is also called a boil, which is an abscess (collection of pus) of the skin or in the deep part of the hair follicles (furunculosis). By definition, furuncles are deeper boils or in the deep part of the hair follicles (furunculosis) with the most common infection usually caused by bacteria called Staphylococcus aureus (S. aureus) either methicillin-sensitive Staphylococcus aureus (MSSA) or methicillin-resistant Staphylococcus aureus (MRSA). What makes methicillin-resistant Staphylococcus aureus (MRSA) different from a typical Staphylococcus aureus (S. aureus) infection is its resistance to the antibiotic methicillin and other common antibiotics, such as amoxicillin, oxacillin, and penicillin. This means these antibiotics do not work on the infection. That’s why an MRSA infection is so difficult to treat. Boils (furuncles) usually start as reddish or purplish, tender bumps. The bumps quickly fill with pus (a mixture of bacteria and infection-fighting white blood cells), growing larger and more painful until they rupture and drain. Areas most likely to be affected by furuncle (boil) are the face, back of the neck, shoulders, armpits, the back, breasts, thighs, groin, and buttocks. Occasionally the infection may spread into the surrounding tissues (cellulitis) and can cause fever and a feeling of being unwell. When several boils form close together and join, this is known as a carbuncle. Sometimes rarer types of Staphylococcus aureus (S. aureus) known as Methicillin resistant Staphylococcus aureus (MRSA) and Panton-Valentine leukocidin Staphylococcus aureus (PVL-SA), can cause furuncles (boils) 1), 2). Panton-Valentine leukocidin (PVL) is an exotoxin produced by certain strains of Staphylococcus aureus (S. aureus). Panton-Valentine leukocidin Staphylococcus aureus (PVL-SA) may cause larger and more painful boils.

Many people are “carriers” of the Staphylococcus aureus (“staph”) bacteria, meaning that it normally lives on their skin or in their nose, belly button (umbilicus) or perineum (your groin, the area of the body between the anus and the vulva in females, and between the anus and the scrotum in males) without doing them any harm. Why this occurs is usually not known, but it is estimated that 10–20% of the population are staphylococcal carriers. Tiny breaks in the surface of the skin (such as those caused by friction or scratching), however, can help the bacteria gain entry into and infect the hair follicle, resulting in a boil. The bacteria, Staphylococcus aureus (S. aureus), causing the furuncle (boil) can occasionally spread from one part of the body to another and from one person to another by skin-to-skin contact and from clothing and towels which have been contaminated with pus from the boil. This is especially true when boils are caused by the PVL strain of Staphylococcus aureus (PVL-SA) bacteria. Furuncles most commonly affects adolescents or teenagers and young adults and is rarely seen in childhood. Sufferers of furuncles do not usually have a problem with their immune system, but boils can be more severe in patients with a suppressed immune system. Furuncles are more common in patients with diabetes and those who are overweight. Furuncle more commonly affects males. Predisposing factors include Staphylococcus aureus (S. aureus) carriage, friction, malnutrition, poor hygiene, possibly diabetes, hyper-IgE syndrome, and human immunodeficiency virus (HIV) infection.

Clinically, furuncles (boils) are painful particularly when in the nose or ear canal. Furuncles (boils) often appear in crops. Patients may describe pus drainage. They usually occur on the face, neck, armpits, buttocks, thighs, and groin. When on the central face, cavernous sinus thrombosis is a rare complication. Lesions may continue to develop for months to years, but individual lesions often heal spontaneously within 2 to 3 weeks.

Methicillin-resistant Staphylococcus aureus (MRSA) first emerged as an important hospital acquired (nosocomial) pathogen in the 1960s. In more recent years, community-acquired outbreaks of MRSA (CA-MRSA) have been described increasingly among healthy individuals lacking the traditional risk factors for such infections (e.g., IV drug use, incarceration, participation in contact sports). These strains have a tendency for causing abscesses, furunculosis, and folliculitis and have a unique antibiotic susceptibility profile from health care-associated strains of MRSA (HA-MRSA) 3).

Immunocompromised patients have a significantly increased risk of developing both methicillin-sensitive Staphylococcus aureus (MSSA) and MRSA furunculosis. HIV-infected patients are approximately 20 times more likely to develop skin and soft tissues infections caused by MRSA. Risk factors for MRSA infection in this population are low current CD4 cell count, recent beta-lactam antibiotic use, and high-risk sexual activity.

Furuncles (boils) can develop anywhere on your skin, but you’re most likely to get one in an area where there’s a combination of hair, sweat and friction, such as the neck, face or thighs. Over time, pus forms inside the boil, making it bigger and more painful. Most boils eventually burst and the pus drains away without leaving a scar. This can take from two days to three weeks to happen.

Boils may resolve with simple self-care measures, but the infected fluid (pus) needs to drain in order for them to heal completely. Many boils drain of their own accord, or they can be lanced by a health care professional. Antibiotics may also be prescribed. Untreated boils can enlarge or grow together to form a giant multi-headed boil (carbuncle). Rarely, the infection in the skin can get into the bloodstream, leading to serious illness.

Furuncles (boils) are most common in teenagers and young adults.

People that are particularly prone to developing boils include:

  • Athletes participating in contact sports or using shared equipment.
  • Individuals with a weakened immune system, such as persons with HIV, diabetics, and those taking certain medications such as the types of medications
  • used to prevent rejection of a transplanted organ or to treat cancer (chemotherapy).
  • Individuals with another skin condition that may lead to scratching or other injury to the skin (eczema, scabies).
  • Staph carriers.
  • People who are obese.
  • Individuals with poor nutrition.
  • People living in close quarters with others (military barracks, prison, homeless shelters).

Furuncle (boil) signs and symptoms of a boil usually include:

  • A painful, red bump that starts out small and can enlarge to more than 2 inches (5 centimeters)
  • Reddish or purplish, swollen skin around the bump
  • An increase in the size of the bump over a few days as it fills with pus
  • Development of a yellow-white tip that eventually ruptures and allows the pus to drain out

It can sometimes be difficult to tell the difference between a furuncle (boil) and an acne, but furuncles (boils) tend to grow bigger and become more painful. Your doctor should be able to diagnose a boil from its appearance. If a boil contains pus, the doctor may use a sterilized needle to take a sample of the pus which can then be swabbed and sent to the laboratory to check which bacteria are causing the boil and which antibiotic treatment may be appropriate.

Pus needs to drain before a boil will heal. This may happen by itself, but sometimes your doctor will need to treat it. One of the best ways to speed up healing is to apply a warm, moist face cloth to the boil for 10-20 minutes, three or four times a day. The heat increases the amount of blood circulating around the boil, which sends more infection-fighting white blood cells to the area.

When the boil bursts, cover it with sterile gauze or a dressing to prevent the spread of infection. Afterwards, wash your hands thoroughly using hot water and soap.

Never squeeze or pierce a boil because it could spread the infection. Pus contains bacteria so avoid getting the pus from the boil onto other areas of the skin. If pus is discharged, wash the area around carefully with an antibacterial product and also wash the hands to avoid spreading the infection.

You can use over-the-counter painkillers, such as acetaminophen or ibuprofen, to help relieve any pain caused by the boil.

For larger furuncle, treatment may include:

  • Incision and drainage. Your doctor may drain a large boil or carbuncle by making an incision in it. Deep infections that can’t be completely drained may be packed with sterile gauze to help soak up and remove additional pus.
  • Antibiotics. Sometimes your doctor may prescribe antibiotics to help heal severe or recurrent infections.
When to see a doctor

See your doctor if:

  • You have multiple boils (carbuncle) or if the boil(s) increases in size or number.
  • You have a fever or chills, severe pain, or otherwise feel unwell.
  • The boil fails to drain.
  • The area of redness surrounding the boil begins spreading.
  • You have diabetes, a heart murmur, a problem with your immune system, or are taking immune-suppressing medications when you develop a boil.
  • You have had repeated outbreaks of boils.

If you are currently being treated for a skin infection that has not improved after 2–3 days of antibiotics, return to your doctor.

What is carbuncle?

A carbuncle is a cluster of boils that form a connected area of infection. Compared with single boils, carbuncles cause a deeper and more severe infection and are more likely to leave a scar. People who have a carbuncle often feel unwell in general and may experience a fever and chills.

Furuncle causes

Furuncles (boils) and carbuncles (a cluster of boils) are often caused by a type of bacteria called Staphylococcus aureus (S. aureus) a type of bacteria commonly found on your skin and inside your nose that infects one or more hair follicles 4), 5). Staph bacteria usually live harmlessly on the surface of the skin or in the lining of the nose. Furuncles (boils) sometimes develop at sites where the skin has been broken by a small injury or an insect bite, which gives the bacteria easy entry. Your immune system responds by sending infection-fighting white blood cells to kill the bacteria. Over time, a mixture of dead bacteria, dead white blood cells and dead skin cells builds up inside the boil to form pus.

People with diabetes, dermatitis, and a weakened immune system are more likely to develop staph infections that can cause furuncles (boils).

Risk factors for furuncles

Although anyone — including otherwise healthy people — can develop boils or carbuncles, the following factors can increase your risk:

  • Close contact with a person who has a staph infection. You’re more likely to develop an infection if you live with someone who has a boil or carbuncle.
  • Diabetes. This disease can make it more difficult for your body to fight infection, including bacterial infections of your skin.
  • Other skin conditions. Because they damage your skin’s protective barrier, skin problems, such as acne and eczema, make you more susceptible to boils and carbuncles.
  • Compromised immunity. If your immune system is weakened for any reason, you’re more susceptible to boils and carbuncles.

Furuncle prevention

It’s not always possible to prevent furuncle, especially if you have a weakened immune system. But the following measures may help you avoid staph infections:

  • Wash your hands regularly with mild soap. Or use an alcohol-based hand rub often. Careful hand-washing is your best defense against germs.
  • Keep wounds covered. Keep cuts and abrasions clean and covered with sterile, dry bandages until they heal.
  • Avoid sharing personal items. Don’t share towels, sheets, razors, clothing, athletic equipment and other personal items. Staph infections can spread via objects, as well as from person to person. If you have a cut or sore, wash your towels and linens using detergent and hot water with added bleach, and dry them in a hot dryer.
  • Change towels every day and do not share them with anybody else.
  • Bath or shower daily, and keep your hands and nails clean. Avoid picking any sores.
  • Wash your hands several times daily or use antiseptic hand rubs.
  • Wash bed sheets at least weekly or at once if pus is discharged.
  • Keep your house clean, especially the sink, shower or bath.
  • Being overweight encourages boils, as the bacteria survive in folds of the skin; in such cases weight loss with regular exercise may help prevent recurrence.
  • If the boils are on exposed skin, avoid close contact with others and contact sports, such as rugby and judo, until the boils have cleared to reduce the risk of passing the infection onto others.
    Do not visit a swimming pool or a gym until the boils have cleared up.
  • Follow a balanced healthy diet with meat, plenty of fruit and vegetables.
  • Avoid smoking.
  • Maintain a clean handkerchief and don’t pick your nose.
  • Change your underclothes and night attire regularly.
  • Consider modifying leisure activities that cause sweating and friction from clothing, such as squash and jogging.
  • If you are iron deficient, a course of iron tablets may help reduce infection.
  • 1000 mg of vitamin C each day has also been suggested to improve defective neutrophil (a type of white blood cell) function.

Furuncle signs and symptoms

Furuncle (boil) may be single or multiple and can occur anywhere on your skin. A furuncle or boil is a painful pus-filled bump that forms under your skin when bacteria infect and inflame one or more of your hair follicles. The most common areas for furuncles (boils) to occur are places where there is friction and/or places that tend to be sweaty, such as your back, breasts, thighs, buttocks, armpits, groin, neck, shoulders, and face. A boil often starts as an itchy or tender spot that grows over a few days into a large firm red lump which becomes very painful. Boils inside the nose or ear, or under tight clothing can be particularly uncomfortable. The skin surrounding the lump may look swollen and red. The center of the lump eventually becomes filled with yellow or white pus that you will be able to see called “coming to a head”. The pus is a mixture of bacteria and infection-fighting white blood cells.

As the furuncle continues to grow the center eventually softens and becomes filled with pus. The pus may then burst through the surface of the skin or it may settle gradually without bursting.

A healed boil tends to leave a red mark, which slowly fades, but can leave a scar.

Furuncle complications

Rarely, bacteria from a furuncle can enter your bloodstream and travel to other parts of your body. The spreading infection, commonly known as blood poisoning or sepsis, can lead to infections deep within your body, such as your heart (endocarditis) and bone (osteomyelitis).

Furuncle diagnosis

Your doctor will likely be able to diagnose furuncle or a boil simply by looking at it. A sample of the pus may be sent to the lab for testing. This may be useful if you have recurring infections or an infection that hasn’t responded to standard treatment.

Many varieties of the bacteria that cause furuncles (boils) have become resistant to certain types of antibiotics. So lab testing can help determine what type of antibiotic would work best in your situation.

Furuncle treatment

A single small furuncle usually gets better naturally, especially if the pus it contains discharges spontaneously. However, occasionally your doctor may release the pus by cutting carefully into the boil (lancing) using sterile instruments. An antibacterial cream, ointment or solution can be used around the boil to stop other boils from appearing nearby. Often an antibiotic is given by mouth, to help clear the infection.

For larger furuncle, treatment may include:

  • Incision and drainage. Your doctor may drain a large boil or carbuncle by making an incision in it. Deep infections that can’t be completely drained may be packed with sterile gauze to help soak up and remove additional pus.
  • Antibiotics. Sometimes your doctor may prescribe antibiotics to help heal severe or recurrent infections.

Never squeeze or lance a boil yourself. This can spread the infection. Pus contains bacteria so avoid getting the pus from the boil onto other areas of the skin. If pus is discharged, wash the area around carefully with an antibacterial product and also wash the hands to avoid spreading the infection.

Wash your hands thoroughly after treating a boil. Also, launder clothing, towels or compresses that have touched the infected area, especially if you have recurrent infections. The doctor may prescribe a topical treatment such as an antibacterial soap, solution or cream to wash with. Sometimes an antibacterial nasal ointment is recommended be applied into each nostril for 5-7 days. Family members may also have to use these treatments if they are found to be carriers. It often helps for family members to use antibacterial washes if they are in close contact and share the same bed.

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