Furunculosis

Published on 19/03/2015 by admin

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Last modified 19/03/2015

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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

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:

Severe or extensive disease (e.g., involving multiple sites of infection)

Rapid progression in presence of associated cellulitis

Signs and symptoms of systemic illness

Associated comorbidities/immunosuppression (diabetes mellitus, HIV/AIDS, neoplasm)

Extremes of age

Abscess in area difficult to drain completely (e.g., face, hand, and genitalia)

Associated septic phlebitis

Lack of response to incision and drainage alone

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.

Specific investigations

Culture and sensitivity of purulent drainage

Acid-fast stain and culture (if indicated)

Moistened nasal swab for culture (if recurrent)

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