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AlexanderSalava

Skin Abscess and Folliculitis

Essentials

  • Minor skin abscesses (boils) can be treated by incision and drainage without the need for systemic antimicrobials.
  • Recurrent abscesses (furunculosis) call for the identification of predisposing factors, improvement of personal hygiene and, if necessary, topical treatment of nasal staphylococcal colonisation.

Aetiology and terminology

  • The most common causative agent is Staphylococcus aureus.
  • If the inflammation is limited to the hair follicle the condition is called folliculitis (pictures 1 2).
  • If the inflammation spreads to the surrounding tissues the condition is referred to as an abscess (a furuncle, pictures 3 4).
  • An abscess may spread further via cutaneous interconnecting channels to form an aggregate of furuncles, i.e. a carbuncle.
  • Sycosis barbae (barber's itch) is deep folliculitis of the beard region (pictures 5 6).
  • Hot tub folliculitis is usually caused by gram-negative bacteria (e.g. Pseudomonas aeruginosa). A few days after bathing (e.g. in a spa), pustules appear on the body and extremities (especially on skin areas under the bathing suit).

Diagnosis

  • Diagnosis is based on clinical presentation.
  • Often seen on the face and hairy skin areas, scalp, groins, thighs and axillae.
  • Folliculitis manifests as a yellowish pustule of 1-3 mm diameter with surrounding erythema.
  • An abscess is a hot, red and painful lump under the skin, which may exude purulent material when “ripe”.

Investigations

  • Bacterial culture is only indicated in complicated or prolonged cases.
  • In the case of poor treatment response, the possibility of MRSA Multidrug-Resistant Bacteria in Hospitals should be kept in mind, especially if there is preceding history of travel or hospital care abroad.
  • In recurrent infections, S. aureus colonisation can often also be demonstrated by bacterial culture of the nostrils, frequently revealing a PVL (Panton-Valentine leucosidin) exotoxin-producing strain.
  • Fungal samples (for microbiology and culture) whenever tinea is suspected.

Differential diagnosis

  • The most important differential diagnoses are the early stages of erysipelas Erysipelas, cellulitis and necrotising infections Severe Infections of the Skin and Soft Tissues.
  • Keep in mind the possibility of secondary cellulitis if the patient has general symptoms or if the erythema extends widely outside the abscess area.
  • It is important to identify causes other than infectious ones.
    • Acne, acneiform drug eruptions, rosacea
    • Oily skin creams, occupational provoking factors (e.g. oils and halogenated hydrocarbons), skin occlusion (e.g. plasters), friction, sweating and maceration, hair removal with a razor blade.
    • In individuals with more pigmented skin types, pseudofolliculitis of the beard area (pseudofolliculitis barbae) and neck (acne cheloidalis nuchae).
  • The following pathogens may also cause a clinical picture that resembles folliculitis:
    • tinea (particularly around the beard area and scalp)
    • herpes and Herpes varicella-zoster (may cause grouped pustules)
    • gram-negative bacteria, such as Pseudomonas aeruginosa (for example, from dirty jacuzzi pools or following a long course of antimicrobials) or Malassezia yeast (on the back or chest).

Treatment

Topical treatment

  • The treatment of folliculitis is usually topical.
  • On hairy skin areas (e.g. thighs) superficial folliculitis is a physiological phenomenon that doesn't always need treatment.
  • The affected areas should be washed with soap or a low pH skin cleanser.
  • If necessary, antimicrobial creams (e.g. fusidic acid) or antiseptic preparations (e.g. chlorhexidine or benzoyl peroxide) may be used.
  • Hot tub folliculitis usually heals spontaneously. Treatment is primarily with topical antiseptic treatments (e.g. chlorhexidine or benzoyl peroxide washes).

Systemic antimicrobials Antibiotics in the Treatment of Superficial Abscesses

  • For extensive folliculitis or small abscesses (no palpable fluctuation), local treatment and/or systemic antimicrobial therapy alone is often sufficient.
  • First-line antibicrobial drugs include flucloxacillin 750-1 000 mg 3 times daily or cephalexin 500 mg 3 times daily; duration of treatment 7-10 days. In the case of hypersensitivity, clindamycin can be used.

Incision and drainage of an abscess

  • The mainstay of treatment is surgical incision and drainage.
  • In an acute phase the abscess is incised under local anaesthesia (for example, a scalpel blade no. 11).
  • The debridement of any infected necrotic tissue and pus is carried out with a suitable instrument and the cavity is rinsed with, for example, physiological saline.
  • A ribbon gauze dressing (e.g. Sorbact® ) may be left in the cavity to absorb the bacterial mass. The cavity is irrigated twice daily for a few days.
  • In addition to the above, an antimicrobial cream is used in mild cases.
  • Systemic antimicrobials after an incision and drainage of an abscess
    • Systemic antimicrobials are usually not indicated.
    • In addition to opening the abscess, systemic antimicrobial therapy for staphylococci is usually needed in cases where the patient has
      • general symptoms
      • an extensive abscess and significant tissue damage
      • immunosuppression or other risk factor (diabetes, prosthetic joint)
      • multiple abscesses
      • recurrence of the abscess despite opening, or
      • abscess in the facial area or near a foreign body (e.g. prosthesis).
    • First-line antibicrobial drugs include flucloxacillin 750-1 000 mg 3 times daily or cephalexin 500-750 mg 3 times daily, in children 50 mg/kg/day; duration of treatment 7-10 days. Also other antimicrobials effective against S. aureus can be used: for example a combination of amoxicillin and clavulanic acid 875/125 mg twice daily.
  • In cases of hypersensitivity, alternative antimicrobials against staphylococci may be used, e.g. clindamycin or sulphamethoxazole/trimethoprim.
  • The dosage is determined based on the severity of the infection, not on the patient's weight.
  • If the abscess is caused by an infected epidermal cyst (picture 7), this should be removed together with its capsule once the acute phase has subsided.
  • Pilonidal sinus: see Pilonidal Sinus.

Furunculosis

  • Recurrent occurrence of furuncles
  • Aetiology is unknown, but hereditary factors, diabetes, immunosuppression (picture 8) and undernourishment all predispose the person to furunculosis.
  • Furunculosis may begin after a journey abroad (particularly in countries with warm climate) Skin Problems in Returning Travellers.
  • Cases refractory to treatment
    • Bacterial culture is indicated since MRSA may be the cause of recurrent furuncles.
    • Additionally, it is a good idea to ask the laboratory to determine PVL (Panton-Valentine leukocidin), i.e. an exotoxin specific to S. aureus bacteria. Both methicillin-sensitive (MSSA) and methicillin-resistant (MRSA) S. aureus may produce it.
  • It is important to differentiate furunculosis from acne (e.g. acne conglobata Acne) and hidradenitis suppurativa (deep furuncular lesions in flexural sites).
  • The following measures are recommended in furunculosis: improved personal hygiene, antiseptic cleansing lotions (e.g. chlorhexidine or benzoyl peroxide) or antimicrobial creams, daily changing of bed linen, towels and clothing.
  • Predisposing factors should be investigated.
  • Moreover, the eradication of nasal S. aureus colonisation may be attempted with antibacterial creams, e.g. mupirocin cream twice daily for 5 days or fusidic acid cream for 1-2 weeks.
  • As an addition to the topical treatment in severe cases (> 3 recurrences/6 months), clindamycin 150 mg 1-2 times daily for 1-3 months may be given as prophylactic treatment. Antimicrobials from the tetracycline, sulpha and macrolide groups have also been used.

Consultation

  • Emergency treatment in a hospital and, if indicated, surgery is recommended in complicated abscesses, severe skin infections and septic conditions Severe Infections of the Skin and Soft Tissues.
  • In furunculosis refractory to treatment, a specialist in dermatology or infectious diseases should be consulted (verification of diagnosis, implementation of more effective eradication treatment).

Pictures

    References

    • Osborne E, Bilalian C, Cussans A, et al. Pseudomonas folliculitis: a complication of the lockdown hot tub boom? Lessons from a patient. Br J Gen Pract 2021;71(702):43-44 [PubMed]
    • Bartoszko JJ, Mertz D, Thabane L, et al. Antibiotic therapy for skin and soft tissue infections: a protocol for a systematic review and network meta-analysis. Syst Rev 2018;7(1):138. [PubMed]
    • Butler-Laporte G, De L'Étoile-Morel S, Cheng MP, et al. MRSA colonization status as a predictor of clinical infection: A systematic review and meta-analysis. J Infect 2018;77(6):489-495. [PubMed]
    • Wang W, Chen W, Liu Y, Siemieniuk RAC, Li L, Martínez JPD, Guyatt GH, Sun X. Wang W, Chen W, Liu Y, et al. Antibiotics for uncomplicated skin abscesses: systematic review and network meta-analysis. BMJ Open 2018;8(2):e020991. [PubMed]
    • Vermandere M, Aertgeerts B, Agoritsas T, Liu C, Burgers J, Merglen A, Okwen PM, Lytvyn L, Chua S, Vandvik PO, Guyatt GH, Beltran-Arroyave C, Lavergne V, Speeckaert R, Steen FE, Arteaga V, Sender R, McLeod S, Sun X, Wang W, Siemieniuk RAC. Vermandere M, Aertgeerts B, Agoritsas T, et al. Antibiotics after incision and drainage for uncomplicated skin abscesses: a clinical practice guideline. BMJ 2018;(360):k243. [PubMed]
    • Yu Y, Cheng AS, Wang L, et al. Hot tub folliculitis or hot hand-foot syndrome caused by Pseudomonas aeruginosa. J Am Acad Dermatol 2007;57(4):596-600 [PubMed]