Why Individuals Develop Recurrent Carbuncles
The primary reason individuals experience recurrent carbuncles is persistent colonization with Staphylococcus aureus in the anterior nares or perineum, which serves as a reservoir for repeated self-inoculation and infection. 1
The Core Mechanism of Recurrence
Nasal carriage of S. aureus is the single most identifiable predisposing factor for recurrent furunculosis and carbuncles in most patients, with 20-40% of the general population being nasal carriers, though why only some carriers develop recurrent infections remains unclear. 1
The bacteria colonize these sites asymptomatically and repeatedly seed the skin, particularly in areas prone to friction, moisture, and hair follicles (especially the back of the neck where carbuncles commonly occur). 1
A minority of patients, particularly children with recurrent infections beginning in early childhood, may have abnormal systemic host responses or neutrophil disorders that impair their ability to clear staphylococcal infections. 1
Contributing Risk Factors
Host-Related Factors
Diabetes mellitus significantly increases susceptibility to carbuncles, particularly those developing on the back of the neck. 1
Immunocompromised states and impaired host defenses create vulnerability to recurrent infections. 1
Recent evidence suggests incomplete or absent protective immunity among patients with recurrent S. aureus skin infections, with defects in both innate and T cell-mediated immunity playing critical roles. 2
Environmental and Behavioral Factors
Inadequate personal hygiene and close personal contact with others who have furuncles are important predisposing factors, particularly in settings like households, prisons, sports teams, and outdoor recreation groups. 1
Contaminated fomites (towels, clothing, bed linens) can harbor S. aureus and facilitate transmission and reinfection. 1
Skin injury and trauma, common in contact sports or certain occupations, provide entry points for bacteria. 1
Bacterial Virulence Factors
The presence of Panton-Valentine leukocidin (PVL) genes in S. aureus strains shows a very tight epidemiological linkage with furunculosis, detected in 85% of furunculosis strains versus less than 1% of colonizing strains. 3
Both methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) can cause recurrent infections. 1
Evidence-Based Prevention Strategy
Decolonization Approach (Most Effective)
For patients with documented nasal colonization, oral clindamycin 150 mg daily for 3 months is the most effective regimen, decreasing subsequent infections by approximately 80% when the organism is susceptible. 1
Intranasal mupirocin ointment applied twice daily for the first 5 days of each month reduces recurrences by approximately 50%, though this is less effective than prolonged clindamycin. 1
The 2014 IDSA guidelines recommend considering a 5-day decolonization regimen including twice-daily intranasal mupirocin, daily chlorhexidine washes, and daily decontamination of personal items for recurrent S. aureus infections. 1
Hygiene Measures
Bathing with antibacterial soaps such as chlorhexidine helps reduce skin bacterial load. 1
Thorough laundering of clothing, towels, and bed linens in hot water is essential. 1
Separate use of towels and washcloths prevents household transmission. 1
Clinical Evaluation for Recurrent Cases
Search for local anatomical causes such as pilonidal cysts, hidradenitis suppurativa, or retained foreign material when abscesses recur at the same site. 1
Culture recurrent lesions early to identify the causative organism and guide antibiotic selection, particularly to detect MRSA. 1
Evaluate adult patients for neutrophil disorders only if recurrent abscesses began in early childhood, as those developing infections in adulthood typically do not have underlying immune defects. 1
Common Pitfalls to Avoid
Do not assume all recurrences are due to treatment failure—most result from persistent colonization rather than inadequate initial therapy. 1
Do not overlook diabetes screening in patients with recurrent carbuncles, especially those on the posterior neck. 1
Avoid using systemic antibiotics alone without addressing the colonization reservoir, as this will not prevent recurrence. 1
Few systemic antibiotics achieve adequate levels in nasal secretions for protracted elimination of staphylococci—clindamycin is a notable exception. 1