Aboil, also called afuruncle, is a deepfolliculitis, which is aninfection of thehair follicle. It is most commonly caused by infection by thebacteriumStaphylococcus aureus, resulting in a painful swollen area on theskin caused by an accumulation ofpus and dead tissue.[1] Boils are therefore basically pus-filled nodules.[2] Individual boils clustered together are calledcarbuncles.[3]Most human infections are caused by coagulase-positiveS. aureusstrains, notable for the bacteria's ability to producecoagulase, anenzyme that can clot blood. Almost anyorgan system can be infected byS. aureus.
Boils are bumpy, red,pus-filled lumps around a hair follicle that aretender, warm, and painful. They range from pea-sized to golf ball-sized. A yellow or white point at 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 experiencefever, swollenlymph nodes, andfatigue. A recurring boil is called chronic furunculosis.[1][4][5][6] 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, andhematologic disorders.[7]
Boils may appear on the buttocks or near the anus, the back, the neck, the belly, the chest, the arms or legs, or even in the ear canal.[8] Boils may also appear around the eye, where they are calledstyes.[9]
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.[14]
Other causes includepoor immune system function such as fromHIV/AIDS,diabetes,malnutrition, oralcoholism.[15] Poor hygiene andobesity have also been linked.[15] It may occur following antibiotic use due to the development of resistance to the antibiotics used.[16] An associated skin disease favors recurrence. This may be attributed to the persistent colonization of abnormal skin withS. aureus strains, such as is the case in persons withatopic dermatitis.[16]Boils which recur under the arm, breast or in the groin area may be associated withhidradenitis suppurativa (HS).[17]
Diagnosis is made through clinical evaluation by a physician, which may include culturing of the lesion.[18] Evaluation can further include imaging, such as an ultrasound, to evaluate for formation of an abscess or other complications.
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 awarm 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 (such as the groin, breasts, armpits, around or in the nostrils, or in the ear).[1][4][5][6] An antibiotic should not be used for longer than one month, with at least two months (preferably longer) between uses, otherwise it will lose its effectiveness.[19]
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.[1][6] Fever and chills are signs ofsepsis and indicate immediate treatment.[20]
Staphylococcus aureus has the ability to acquireantimicrobial resistance easily, making treatment difficult. Knowledge of the antimicrobial resistance ofS. aureus is important in the selection of antimicrobials for treatment.[21]
^abBlume JE, Levine EG, Heymann WR (2003). "Bacterial diseases". In Bolognia JL, Jorizzo JL, Rapini RP (eds.).Dermatology. Mosby. p. 1126.ISBN0-323-02409-2.
^abcdHabif, TP (2004). "Furuncles and carbuncles".Clinical Dermatology: A Color Guide to Diagnosis and Therapy (4th ed.). Philadelphia PA: Mosby.
^abcdeWolf K; et al. (2005). "Section 22. Bacterial infections involving the skin".Fitzpatrick's Color Atlas & Synopsis of Clinical Dermatology (5th ed.). McGraw-Hill.
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