What is the recommended antibiotic for a pilonidal cyst with signs of infection?

Antibiotic Selection for Infected Pilonidal Cysts

For pilonidal cysts with signs of infection, the recommended first-line antibiotic regimen is clindamycin 300-450 mg orally three times daily plus trimethoprim-sulfamethoxazole (1-2 double-strength tablets twice daily) for 5-7 days, always as an adjunct to incision and drainage. 1, 2, 3

When Antibiotics Are Indicated

Antibiotics should be added to surgical drainage only when specific criteria are met:

• Systemic inflammatory response syndrome (SIRS) is present, including fever, tachycardia, tachypnea, or abnormal white blood cell count 2, 3
• Extensive cellulitis with erythema and induration extending more than 5 cm from the wound edge 3
• Immunocompromised status 3

Primary Antibiotic Regimens

First-Line Therapy

• Clindamycin 300-450 mg orally three times daily PLUS trimethoprim-sulfamethoxazole (1-2 double-strength tablets twice daily) for 5-7 days 1, 2
• This combination targets the polymicrobial flora commonly found in perineal skin and soft tissue infections 1

Alternative Regimens for Penicillin Allergy

• Clindamycin PLUS ciprofloxacin 1, 2
• Note: Fluoroquinolones should be reserved for cases where other antibiotics cannot be used due to their propensity for collateral damage 2

Additional Options for Perineal Infections

• Cefoxitin or ampicillin-sulbactam are effective for infections involving the perineum 1
• Amoxicillin-clavulanate provides broad-spectrum coverage against polymicrobial flora 3

Duration of Therapy

• 5-7 days for most uncomplicated cases following adequate drainage 1
• 10-14 days for severe or complicated infections based on clinical response 1

Special Considerations for Recurrent Infections

For patients with recurrent pilonidal abscesses:

• Culture the abscess and treat with antibiotics active against the isolated pathogen 2, 3
• Consider a 5-day decolonization regimen with intranasal mupirocin and chlorhexidine washes 1, 2

Critical Pitfalls to Avoid

• Failure to adequately drain the abscess is the most common reason for treatment failure, not antibiotic selection 1
• Beta-lactams have inferior efficacy and more adverse effects compared to other antimicrobials for skin infections and should be used with caution 2
• Antibiotics alone without drainage are insufficient—surgical drainage remains the cornerstone of treatment 1, 3
• Amoxicillin or ampicillin monotherapy should not be used due to poor efficacy and high resistance rates 4

Clinical Algorithm

1. Perform incision and drainage as primary treatment 2, 3
2. Assess for systemic signs: temperature, heart rate, respiratory rate, white blood cell count, and extent of erythema 3
3. If systemic signs present: Start clindamycin plus trimethoprim-sulfamethoxazole for 5-7 days 1, 2
4. If penicillin allergy: Use clindamycin plus ciprofloxacin 1, 2
5. For recurrent cases: Culture abscess, treat based on sensitivities, and consider decolonization 2, 3