Should an adult female with myiasis of a bleeding breast mass be treated with antibiotics?

Myiasis of a Bleeding Breast Mass: Antibiotic Management

Antibiotics are not routinely indicated for uncomplicated cutaneous myiasis of the breast, as treatment is based on complete mechanical extraction of the larvae; however, antibiotics should be given if there is evidence of secondary bacterial infection, extensive tissue necrosis, or systemic signs of infection. 1

Primary Treatment Approach

The cornerstone of myiasis management is mechanical removal of all larvae, not antibiotic therapy 1, 2. The following extraction techniques are recommended:

• Apply occlusive substances (petroleum jelly/Vaseline) to the wound opening and cover for 2 hours to suffocate larvae and facilitate easier extraction 3
• Perform gentle manual extraction after occlusion to remove larvae completely 3
• Ensure complete removal of all larvae, as incomplete extraction leads to continued tissue damage and inflammation 1

When Antibiotics ARE Indicated

Antibiotics should be prescribed in the following specific circumstances:

• Secondary bacterial superinfection with purulent drainage, expanding erythema beyond the myiasis site, or systemic signs (fever, chills) 4
• Extensive wound myiasis with significant tissue necrosis or multiple ulcerative lesions 4
• Immunocompromised patients where risk of bacterial superinfection is elevated 5
• Failed initial extraction requiring surgical debridement of necrotic tissue 5

Antibiotic Selection When Needed

If secondary bacterial infection is present, empirical coverage should target Staphylococcus aureus and Streptococcus species, the most common skin pathogens:

• First-line oral options: Cephalexin 500 mg four times daily, dicloxacillin 500 mg four times daily, or clindamycin 300-450 mg three times daily 5
• If MRSA suspected (based on local epidemiology or prior MRSA history): TMP-SMX 1-2 double-strength tablets twice daily, doxycycline 100 mg twice daily, or clindamycin 300-450 mg three times daily 5
• Duration: 7-10 days for uncomplicated secondary infection 5

Critical Diagnostic Pitfalls

Do not misdiagnose myiasis as a simple breast abscess, which leads to unnecessary antibiotic courses and delayed appropriate treatment 3, 2. Key distinguishing features include:

• Recent travel history to tropical/subtropical regions (especially Ghana, Central/South America) 3, 1
• Central punctum with serosanguinous drainage rather than frank purulence 3
• Sensation of movement or visible larvae in the wound 4
• Ultrasound imaging can confirm diagnosis by visualizing larvae and avoiding treatment delays 3

Important Clinical Considerations

• Myiasis mimicking inflammatory breast cancer: If a patient has a history of "mastitis not responding to at least 1 week of antibiotics" with erythema occupying one-third or more of the breast, malignancy must be excluded with core needle or skin punch biopsy before attributing symptoms solely to myiasis 5, 6
• Wound care is essential: Daily antiseptic cleansing with betadine or similar solutions promotes healing after larval extraction 4
• No prophylactic antibiotics: Routine antibiotic prophylaxis after successful larval removal in the absence of infection is not indicated and may promote resistance 1, 2

Post-Extraction Management

After complete larval removal:

• Monitor for 3-5 days to ensure no additional larvae emerge and wound is healing appropriately 4
• Reassess if symptoms worsen or new systemic signs develop, which would warrant antibiotic initiation 5
• Provide wound care instructions including keeping the area clean and dry 4