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

Antibiotic Treatment for Infected Pilonidal Cysts

For infected pilonidal cysts, first-line antibiotic therapy should include coverage against Staphylococcus aureus and anaerobes with a combination of amoxicillin-clavulanate or, if MRSA is suspected, trimethoprim-sulfamethoxazole plus metronidazole.

Pathophysiology and Microbiology

Pilonidal cysts are acquired lesions in the sacrococcygeal region that become infected when bacteria colonize the area. When infected, these cysts typically contain:

• Staphylococcus aureus (including potential MRSA)
• Mixed anaerobic bacteria
• Gram-negative enteric organisms (due to proximity to the anus)

Antibiotic Selection Algorithm

First-Line Options:

1. Amoxicillin-clavulanate (875/125 mg twice daily orally) 1

   • Provides excellent coverage against both Staphylococcus and anaerobes
   • Duration: 5-7 days

2. If MRSA is suspected or prevalent in your area:

   • Trimethoprim-sulfamethoxazole (1-2 double-strength tablets twice daily) plus metronidazole (500 mg three times daily) 1
   • Duration: 5-7 days

Alternative Options:

1. Cephalexin (500 mg four times daily) plus metronidazole (500 mg three times daily) 1, 2

   • Good option for penicillin-allergic patients without anaphylaxis
   • Duration: 7 days

2. Clindamycin (300-450 mg three times daily) 1

   • Covers both Staphylococcus and anaerobes
   • Good option for penicillin-allergic patients
   • Duration: 7 days

Important Considerations

Surgical Management

• Antibiotics alone are insufficient treatment for infected pilonidal cysts
• Incision and drainage is the recommended primary treatment for inflamed pilonidal cysts 1
• Antibiotics should be considered as adjunctive therapy to surgical drainage when:
  • Systemic signs of infection are present (fever, tachycardia, etc.)
  • Surrounding cellulitis extends beyond the immediate area
  • Patient has impaired host defenses 1

Clinical Pearls

• Recurrent pilonidal abscesses should be drained and cultured early in the course of infection 1
• For recurrent infections, consider a 5-day decolonization regimen with intranasal mupirocin, daily chlorhexidine washes, and decontamination of personal items 1
• Aspiration of pilonidal abscesses followed by antibiotics has shown effectiveness in 83% of cases in selected patients 2

Common Pitfalls to Avoid

1. Treating with antibiotics alone without surgical drainage
2. Failing to cover anaerobic bacteria when selecting antibiotics
3. Not considering MRSA in patients with risk factors or prior MRSA infections
4. Prolonged antibiotic courses when shorter durations (5-7 days) are typically sufficient

Special Situations

Severe Infection or Immunocompromised Patients

For patients with systemic signs of infection (SIRS) or immunocompromised status:

• Vancomycin (15-20 mg/kg IV every 12 hours) plus piperacillin-tazobactam (3.375 g IV every 6-8 hours) 1
• Consider hospitalization for IV antibiotics and close monitoring

Recurrent Infections

• Culture-directed antibiotic therapy for 5-10 days 1
• Consider definitive surgical treatment options to prevent recurrence 3

Remember that while antibiotics are important in managing infected pilonidal cysts, they should be used as an adjunct to appropriate surgical management, which remains the cornerstone of treatment.