What antibiotic is recommended for an infected mucoid cyst?

Treatment of Infected Mucoid Cysts

For an infected mucoid cyst, first-line antibiotic treatment should be flucloxacillin or dicloxacillin, as these penicillinase-resistant penicillins are the antibiotics of choice for methicillin-susceptible Staphylococcus aureus (MSSA) infections, which commonly cause skin and soft tissue infections. 1

Antibiotic Selection Algorithm

First-line options:

• Penicillinase-resistant penicillins:
  • Flucloxacillin (oral or IV depending on severity)
  • Dicloxacillin (oral)

For patients with penicillin allergy:

• Non-immediate hypersensitivity:

  • First-generation cephalosporins (cephalexin)
  • Clindamycin

• Immediate hypersensitivity (urticaria, angioedema, bronchospasm, anaphylaxis):

  • Clindamycin
  • Lincomycin
  • Erythromycin

For suspected or confirmed MRSA:

• Hospital-acquired MRSA:

  • Vancomycin (IV for severe infections)
  • Combination therapy with rifampicin and fusidic acid (for oral treatment)

• Community-acquired MRSA:

  • Clindamycin
  • Cotrimoxazole

Treatment Duration and Approach

The antibiotic treatment should be continued for 7-10 days, depending on clinical response. In addition to antibiotic therapy, the following interventions should be considered:

1. Drainage: Incision and drainage of the infected cyst may be necessary to remove purulent material

2. Definitive treatment options:

   • Aspiration and injection: Can be performed with a 25-gauge needle, though this has a 40% recurrence rate 2
   • Surgical excision: More definitive treatment with no recurrences in studied cases 2
   • Sclerosant injection: Sodium tetradecyl sulfate injection has been reported as effective with minimal complications 3

Important Considerations

• Most mucoid cysts are caused by common skin flora, particularly Staphylococcus aureus, making penicillinase-resistant penicillins the appropriate first choice
• Antibiotic resistance patterns should be considered when selecting therapy
• For severe infections or immunocompromised patients, consider broader coverage initially
• Surgical consultation may be necessary for definitive management after the infection is controlled
• Recurrence is common with conservative management alone

Potential Pitfalls

1. Failure to drain: Antibiotics alone may be insufficient if there is significant purulence that requires drainage
2. Misdiagnosis: Digital mucoid cysts should be differentiated from ganglia as treatment approaches differ 4
3. Inadequate follow-up: Even after successful treatment of infection, the underlying cyst may require definitive management to prevent recurrence
4. Inappropriate antibiotic selection: Using antibiotics without activity against the likely causative organisms

While the evidence specifically addressing infected mucoid cysts is limited, the principles of treating skin and soft tissue infections apply. The combination of appropriate antibiotics with consideration for surgical intervention provides the best approach for managing these infections.