Folliculitis, furuncles, carbuncles and abscesses are all discussed here.
When a skin infection is confined to a hair follicle, this is called a folliculitis (thanks to www.skinsight.com for this image).
However, when the infection spreads and involves the tissue around the hair follicle as well, this is called a furuncle. In males the back of the neck is an area where furuncles like to occur and if several of them connect subcutaneously, this is called a carbuncle.
Occasionally, when these other conditions are not treated adequately, a skin abscess might form, where some of the subcutaneous tissue has melted away and formed a pus pocket. Diabetes predisposes to carbuncles. They tend to develop slower (several days) and they dissolve very slowly (often weeks) leaving behind a lot of scarring with defects (dimples) in the skin.
Folliculitis, furuncles and carbuncles are commonly due to Staphylococcus aureus, a bacterium, which grows on agar plates in the laboratory as golden yellow spots. It is from this appearance in culture that this bacterium got its name “aureus” (=golden).
With a penetrating wound from a gun shot injury, knife injuries etc. bacteria from the skin or from the penetrating object get into the wound and multiply within a short time.
There is a limited time of 4 to 6 hours that the physician has to clean up and close such a wound. If this time frame is surpassed or if inadvertently pathological bacteria are left behind, an abscess will form. This is an accumulation of pus under pressure. The danger , if this is left alone, is that the bacteria will spread via the lymphatic and blood vessels into the general circulation and into other vital organs. Staphylococcal sepsis, pneumonia, arthritis,osteomyelitis as well as endocarditis can subsequently develop. All of these conditions can be life threatening. Prompt recognition, accurate diagnosis and swift treatment (see below) will save many lives.
Signs and symptoms
Folliculitis presents with a pustule or reddish inflammation around a hair follicle.
There may be several spots of folliculitis. As the bacteria (mostly Staph. aureus) multiply quickly, sometimes the spreading of the infection can be a problem such as in bearded areas of males. Furuncles are acute localized reddish nodules, which are painful, and tend to occur in the neck area, the face, on breasts and buttocks. Often it starts as a pus blister (pustule), which then breaks open and discharges pus and necrotic tissue. If furuncles occur at the nose or the ears they are particularly painful.
Carbuncles are larger and deeper than furuncles, but otherwise are found in the same areas and also tend to break open. Abscesses present as tender, swollen areas of reddened skin, which are hot and tender to touch. There often is a fever associated with it as toxins circulate in the system. If pus migrates through the circulatory system, there could be other new abscesses form in other organs. With a brain abscess there would be signs of a stroke (hemiplegia, with half of the body paralyzed) and with abscesses in other organs there would be specific symptoms in these organs.
The diagnosis is mostly a clinical one. In other words, the symptoms and the history will allow the physician to come to the diagnosis with high accuracy. In the case of skin abscesses blood tests, blood cultures and some other tests may be needed to help with the diagnosis. In deeper abscesses such tests as ultrasound, CT scan and Gallium bone scan might be indicated. Marked increased white blood cell counts (leukocytosis) is usually found in the case of an abscess.
For folliculitis mupirocin ointment (brandname: Bactroban ointment) is applied 3 to 4 times per day to the affected skin.
This is best complemented by oral administration of cloxacillin or cephalexin for 7 to 10 days to interrupt the cycle of reinfection. Furuncles and carbuncles are treated by incision and drainage. Isotretinoin (brand name: Accutane) is useful in severe acne cases where furuncles are frequently also found. Oral antibiotics as for folliculitis are often also given, but for more prolonged periods of time. A deep skin abscess needs incision and drainage by a surgeon. In a large abscess gauze packing or a surgical drainage tube may have to be inserted to allow the wound to heal by “secondary” wound healing (“primary” is direct closure). Antibiotic coverage as above is given at the same time. Close monitoring of the blood tests and of the clinical condition for possible complications needs to be done (Ref. 3, p. 799 and Ref. 2, p. 460).
1.The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 265.
2.James Chin et al., Editors: Control of Communicable Diseases Manual, 17th edition, 2000, American Public Health Association
3.The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 112.
4. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 115.
5. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 113.
6. Suzanne Somers: “Breakthrough” Eight Steps to Wellness– Life-altering Secrets from Today’s Cutting-edge Doctors”, Crown Publishers, 2008