A boil, also called a furuncle, is a deep folliculitis, infection of the hair follicle. It is most commonly caused by infection by the bacteriumStaphylococcus aureus, resulting in a painful swollen area on the skin caused by an accumulation of pus and dead tissue. Boils which are expanded are basically pus-filled nodules. Individual boils clustered together are called carbuncles. Most human infections are caused by coagulase-positive S. aureusstrains, notable for the bacteria's ability to produce coagulase, an enzyme that can clot blood. Almost any organ system can be infected by S. aureus.
Signs and symptoms
Boils are bumpy, red, pus-filled lumps around a hair follicle that are tender, warm, and very painful. They range from pea-sized to golf ball-sized. A yellow or white pointat the center of the lump can be seen when the boil is ready to drain or discharge pus. In a severe infection, an individual may experience fever, swollen lymph nodes, and fatigue. A recurring boil is called chronic furunculosis. Skin infections tend to be recurrent in many patients and often spread to other family members. Systemic factors that lower resistance commonly are detectable, including: diabetes, obesity, and hematologic disorders. Boils can be caused by other skin conditions that cause the person to scratch and damage the skin. Boils may appear on the buttocks or near the anus, the back, the neck, the stomach, the chest, the arms or legs, or even in the ear canal. Boils may also appear around the eye, where they are called styes. A boil on the gum is called intraoral dental sinus, or more commonly, a gumboil.
Complications
The most common complications of boils are scarring and infection or abscess of the skin, spinal cord, brain, kidneys, or other organs. Infections may also spread to the bloodstream and become life-threatening. S. aureus strains first infect the skin and its structures or invade damaged skin. Sometimes the infections are relatively limited, but other times they may spread to other skin areas. Unfortunately, these bacteria can reach the bloodstream and end up in many different body sites, causing infections that may severely harm or kill the infected person. S. aureus strains also produce enzymes and exotoxins that likely cause or increase the severity of certain diseases. Such diseases include food poisoning, septic shock, toxic shock syndrome, and scalded skin syndrome. Almost any organ system can be infected by S. aureus. Squeezing or cutting boils in the danger triangle of the face can be particularly dangerous if done outside a medical setting, as blood vessels in this area drain into the brain and can carry serious infections there. And when burst, a seemingly solid, whitish colored pus initially appears then the pus and some blood follows.
People with recurrent boils are as well more likely to have a positive family history, take antibiotics, and to have been hospitalised, anemic, or diabetic; they are also more likely to have associated skin diseases and multiple lesions.
Other
Other causes include poor immune system function such as from HIV/AIDS, diabetes, malnutrition, or alcoholism. Poor hygiene and obesity have also been linked. It may occur following antibiotic use due to the development of resistance to the antibiotics used. An associated skin disease favors recurrence. This may be attributed to the persistent colonization of abnormal skin with S. aureus strains, such as is the case in persons with atopic dermatitis. Boils which recur under the arm, breast or in the groin area may be associated with hidradenitis suppurativa.
Diagnosis
Diagnosis is made through clinical evaluation by a physician, which may include culturing of the lesion.
Treatment
A boil may clear up on its own without bursting, but more often it will need to be opened and drained. This will usually happen spontaneously within two weeks. Regular application of a warm moist compress, both before and after a boil opens, can help speed healing. The area must be kept clean, hands washed after touching it, and any dressings disposed of carefully, in order to avoid spreading the bacteria. A doctor may cut open or "lance" a boil to allow it to drain, but squeezing or cutting should not be attempted at home, as this may further spread the infection. Antibiotic therapy may be recommended for large or recurrent boils or those that occur in sensitive areas. Antibiotics should not be used for longer than one month, with at least two months between uses, otherwise it will lose its effectiveness. If the patient has chronic boils, removal by plastic surgery may be indicated. Furuncles at risk of leading to serious complications should be incised and drained if antibiotics or steroid injections are not effective. These include furuncles that are unusually large, last longer than two weeks, or occur in the middle of the face or near the spine. Fever and chills are signs of sepsis and indicate immediate treatment is needed. Staphylococcus aureus has the ability to acquire antimicrobial resistance easily, making treatment difficult. Knowledge of the antimicrobial resistance of S. aureus is important in the selection of antimicrobials for treatment.
