Furunculosis

Published on 19/03/2015 by admin

Filed under Dermatology

Last modified 22/04/2025

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Furunculosis

Charles A. Gropper and Karthik Krishnamurthy

Evidence Levels:  A Double-blind study  B Clinical trial ≥ 20 subjects  C Clinical trial < 20 subjects  D Series ≥ 5 subjects  E Anecdotal case reports

image

Furunculosis, commonly referred to as ‘boils,’ is a deep infection of the pilosebaceous unit. Lesions may occur on any hair-bearing surface, including the nares. When many hair follicles are involved, the term carbuncle is used. These large, suppurative lesions are usually very tender and may have multiple draining sites.

Management strategy

The infectious agent most commonly implicated is Staphylococcus aureus; methicillin-resistant strains of S. aureus (MRSA) are now recognized as the dominant isolate overall. In recent years, the designations of community-acquired MRSA (CA-MRSA) versus hospital-acquired MRSA (HA-MRSA) have become blurred due to a convergence in both antibiotic susceptibility profiles and risk of sequelae. Delay in diagnosis and appropriate therapy can lead to systemic involvement, including rare reports of epidural abscess, bacterial endocarditis, and pulmonary infection.

Other culprits such as group A beta-hemolytic Streptococcus and Gram-negative bacteria should remain in the differential diagnosis. In addition, Mycobacterium spp., especially M. fortuitum, have been implicated in non-responsive furunculosis in patients using footbaths in beauty salons.

Nasal, pharyngeal, axillary, perineal, and rectal pathogen carriage is implicated in recurrent disease. In rare cases, patients with impaired neutrophil function and immunodeficiency syndromes, such as common variable immunodeficiency and hyper-IgE syndrome, also present with recurrent furunculosis.

Isolated lesions should be incised and drained. Multiple, mostly observational, studies indicate high post-surgical cure rates (85–90%) whether or not an active antibiotic is used. Therefore, according to the Centers for Disease Control (2006) and Infectious Disease Society of America (2011), empiric antibiotics should be reserved for those with:

Swabs of any purulent discharge should be collected for bacterial culture; antibiotic therapy may be redirected based on sensitivities and clinical scenario. Acid-fast staining and culture may be warranted if a temporal relationship to a pedicure is noted. Currently, antibiotics carrying an FDA indication for use against MRSA include linezolid, ceftaroline (‘advanced’ generation cephalosporin), telavancin (similar to vancomycin), tigecycline (derivative of minocycline), and teicoplanin. These are mainly reserved for complicated infections requiring hospitalization. Other antibiotics with anti-MRSA activity include trimethoprim/sulfamethoxazole (TMP-SX), daptomycin, vancomycin, doxycycline, minocycline, clindamycin, rifampin, and quinupristin–dalfopristin. Evidence of nasal carriage of staphylococci should be sought in those with recurrent disease, and eradicated with either oral rifampicin (not as monotherapy) or nasal mupirocin or fusidic acid.

First-line therapies

imageSurgery: incision and drainage A

Randomized, double-blind, placebo-controlled trial of cephalexin for treatment of uncomplicated skin abscesses in a population at risk for community-acquired methicillin-resistant Staphylococcus aureus infection.

Rajendran PM, Young D, Maurer T, Chambers H, Perdreau-Remington F, Ro P, et al. Antimicrob Agents Chemother 2007; 51: 4044–8.

Randomized, double-blind trial of 166 outpatient subjects comparing placebo to cephalexin at 500 mg orally four times daily for 7 days after incision and drainage of skin and soft tissue abscesses. The primary outcome was clinical cure or failure 7 days after incision and drainage. Of the isolates tested 87.8% were MRSA. Clinical cure rates were 90.5% (95% CI, 0.82 to 0.96) in the 84 placebo recipients and 84.1% (95% CI, 0.74 to 0.91) in the 82 cephalexin recipients (difference in the two proportions, 0.0006; 95% CI, −0.0461 to 0.0472; p=0.25). Provides strong evidence that antibiotics may be unnecessary after surgical drainage of uncomplicated skin and soft tissue abscesses caused by community strains of MRSA.

Second-line therapies

imageDoxycycline or minocycline B
imageTrimethoprim/sulfamethoxazole B
imageClindamycin B
imageLinezolid B

Adjunctive for patients meeting criteria listed in the management strategy section.

Prevalence, severity, and treatment of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) skin and soft tissue infections in 10 medical clinics in Texas: a South Texas Ambulatory Research Network (STARNet) study.

Forcade NA, Parchman ML, Jorgensen JH, Du LC, Nyren NR, Treviño LB, et al. J Am Board Fam Med 2011; 24: 543–50.

Ten primary care clinics took part in this prospective, community-based study. Overall, 73 of 119 (61%) patients presenting with SSTIs meeting eligibility requirements had CA-MRSA. Most received incision and drainage plus an antibiotic (64%). Antibiotic monotherapy was frequently prescribed: TMP-SMX (78%), clindamycin (4%), doxycycline (2%), and mupirocin (2%). The rest received TMP-SMX in combination with other antibiotics. Isolates were 93% susceptible to clindamycin and 100% susceptible to TMP-SMX, doxycycline, vancomycin, and linezolid.

Third-line therapies/prevention

imageNasal mupirocin + chlorhexidine wash + oral antibiotics B
imageNasal mupirocin B
imageBleach bath E
imageColonization with less pathogenic staphylococci E
imageRetapamulin E
imageFusidic acid B

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