Dermatology

Furunculosis (Boil)

Are You Confident of the Diagnosis?

What you should be alert for in the history

Furuncles are most commonly a manifestation of a Staphylococcus aureus infection. Most individuals with furunculosis are nasal carriers of S. aureus. For this reason, many individuals have recurrent disease.

Characteristic findings on physical examination

A furuncle is a localized infection, involving the skin and subcutaneous tissue, in areas with hair follicles. Furuncles are small abscesses, characterized by purulent material, that involve a single hair follicle. Lesions, however, may be multiple (furunculosis), as seen in Figure 1.

Figure 1.

Furunculosis caused by methicillin-resistant Staphylococcus aureus infection.

On physical examination, furuncles are characterized as fluctuant subcutaneous collections, with overlying erythema and edema.

Expected results of diagnostic studies

During drainage of an abscess, a bacterial culture can be obtained in order to determine the causative pathogen. The diagnosis can usually be made on clinical observation.

Diagnosis confirmation

The differential diagnosis includes inflamed cysts, hidradenitis suppurativa, and cutaneous abscesses. A furuncle should be differentiated from a carbuncle, which is an aggregation of connected furuncles and involves more than one hair follicle. These lesions are tender and may have multiple sites of drainage.

Who is at Risk for Developing this Disease?

Furuncles can develop in any individual; however, immunosuppression increases the risk for abscesses. Individuals with the following conditions or on the following medications are at greater risk: chronic steroid therapy, chemotherapy, malignancies, dialysis for kidney failure, acquired immunodeficiency syndrome (AIDS), sickle cell disease, peripheral vascular disease, inflammatory bowel disease, and severe burns.

What is the Cause of the Disease?

Etiology

Pathophysiology

The most common bacterial organism responsible for the development of furuncles is Staphylococcus aureus. With the emergence of methicillin-resistant Staphylococcus aureus (MRSA), health-care providers must now consider this organism as the possible cause when furunculosis is encountered.

Systemic Implications and Complications

Most furuncles are localized and lead to no systemic complications. Rarely, systemic infections can result from complicated and untreated lesions. Some reported complications include endocarditis and pulmonary infections.

Treatment Options

Treatment options are summarized in Table I.

Table I.

Treatment options for furunculosis.
Topical  Systemic  Surgical  Adjunctive
mupirocin ointment antistaphylococcal antibiotics incision and drainage decolonization with mupirocin ointment
   clindamycin   Hibiclens cleanser
   tetracyclines   bleach baths
   trimethoprim-sulfamethoxasole    
   intravenous antibiotics (clindamycin, oxacillin, vancomycin    

Optimal Therapeutic Approach for this Disease

Incision and drainage has been proven to be the mainstay of treatment for abscesses and furuncles. Initial incision and drainage (treatment of skin furuncles without antibiotic treatment) is not significantly associated with increased follow-up visits to a health care provider, subsequent incision and drainage, or change in antibiotic treatment.

Empiric antibiotic therapy should be initiated as an adjunct to incision and drainage, particularly in cases with rapid progression, lesions greater than 5cm, and systemic manifestations, as well as in immunocompromised patients.

β-lactam antibiotics with antistaphylococcal and streptococcal activity are a reasonable initial treatment with careful follow-up in cases of mild skin and soft tissue infections (SSTIs) among otherwise healthy patients residing in areas with low MRSA prevalence. Oral non-β-lactam antibiotics should be initiated for patients with SSTIs unresponsive to initial incision and drainage and β-lactam antibiotics, or cases with a high clinical suspicion of community-acquired MRSA.

These non-β-lactam antibiotics include clindamycin, linezolid, tetracycline, and trimethoprim-sulfamethoxazole. In complicated cases, intravenous antibiotics such as clindamycin, oxacillin, and vancomycin may be required.

In individuals or groups, where there is suspicion of staphylococcal carriage, decolonization may be indicated. Application of mupirocin ointment to the nares, umbilicus, axillae, groin, and perineum can be utilized to eradicate colonization. In addition, antiseptic agents and bleach baths may be utilized. For bleach baths, 1/4 to 1/2 cup of common liquid bleach can be added to a full tub.

Patient Management

Patients should be followed for recurrent furunculosis because it is a sign that they may be persistently colonized with staphylococci. Repeated decolonization or referral to an infection disease specialist should be considered. Decolonization of family members may be required.

Unusual Clinical Scenarios to Consider in Patient Management

Patients who are immunocompromised or have other comorbidities should be followed closely. If a patient has a worsening infection, fever, and chills, immediate follow-up should be arranged to rule out the development of cellulitis or systemic spread.

What is the Evidence?

Atanaskova, N, Tomecki, KJ. "Innovative management of recurrent furunculosis". Dermatol Clin. vol. 28. 2010. pp. 479-87.

(A review of the comprehensive management of recurrent furunculosis.)

Liu, C, Bayer, A, Cosgrove, SE, Daum, RS, Fridkin, SK, Gorwitz, RJ, Kaplan, SL. "Clinical practice guidelines by the Infectious Diseases Society of America for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children".

(These are current evidence-based guidelines for the management of patients with methicillin-resistant Staphylococcus aureus [MRSA] infections.)

Moran, GJ, Amil, RN, Abrahamian, FM, Talan, DA. "Methicillin-resistant Staphylococcus aureus in community-acquired skin infections". Emerg Infect Dis. vol. 11. 2005. pp. 928-930.

(The article reviews the increasing incidence of MRSA.)
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