Antibiotic Regimen for Fishhook Injury
For uncomplicated fishhook injuries involving soft tissue only, prophylactic antibiotics are not routinely necessary, but when antibiotics are indicated (cartilage involvement, delayed presentation, immunocompromise, or contaminated wounds), amoxicillin-clavulanate 875/125 mg twice daily for 5-7 days is the first-line choice. 1, 2
When Antibiotics Are NOT Needed
Routine prophylactic antibiotics are unnecessary for simple, uncomplicated soft tissue fishhook injuries not involving cartilage or tendons. 3 A prospective study of 100 consecutive fishhook injuries demonstrated that postremoval wound care including oral antibiotic therapy may not be critical for straightforward cases. 3
A more recent retrospective analysis of 51 fishhook injuries found zero wound infections or complications in cases where the fishhook was removed during the emergency department encounter, regardless of whether prophylactic antibiotics were prescribed. 4
When Antibiotics ARE Indicated
Prophylactic antibiotics should be prescribed for: 2, 3
- Injuries involving cartilage (e.g., ear) 3
- Injuries involving tendons or deep structures 3
- Delayed presentation (>6-12 hours) 2
- Immunocompromised patients (diabetes, immunosuppression) 2
- Grossly contaminated wounds 2
- Wounds with retained foreign material 2
First-Line Antibiotic Regimen
Amoxicillin-clavulanate 875/125 mg orally twice daily for 5-7 days is the recommended first-line therapy. 1, 2 This combination provides:
- Excellent coverage against Staphylococcus aureus and Streptococcus species (common skin flora) 1, 2
- Coverage of anaerobic bacteria from environmental contamination 1, 2
- Activity against Aeromonas species, a freshwater pathogen that can complicate fishhook injuries 5, 4
- Broad gram-negative coverage 1
The IDSA guidelines for skin and soft tissue infections specifically recommend amoxicillin-clavulanate for animal bite wounds and contaminated puncture injuries, which share similar microbiology with fishhook injuries. 1
Alternative Regimens for Penicillin Allergy
For penicillin-allergic patients: 1, 2
Doxycycline 100 mg orally twice daily provides good activity against staphylococci, streptococci, and some anaerobes, though some streptococci may be resistant 1, 2
Moxifloxacin 400 mg orally once daily offers good anaerobic coverage and broad-spectrum activity, though fluoroquinolone stewardship concerns make this second-line 1, 2
Avoid first-generation cephalosporins alone (e.g., cephalexin), as they miss anaerobes and some gram-negative organisms relevant to environmental contamination 1
Microbiological Considerations
The microbiology of fishhook injuries includes: 2, 6
- Skin commensals (Staphylococcus aureus, Streptococcus species) are the most common pathogens 6
- Anaerobic bacteria from environmental contamination 1, 2
- Aeromonas hydrophila (freshwater pathogen) 5, 4
- Rarely, marine-specific bacteria like Photobacterium damselae (saltwater) 6
A prospective study of fish spike injuries found that 88% of clinically relevant bacteria were susceptible to amoxicillin-clavulanate, with only 12% showing resistance (primarily MRSA). 6 True marine-specific bacteria were rare (2% of cases). 6
Important Caveats and Pitfalls
MRSA coverage should be added if: 2
- Prior history of MRSA colonization or infection 2
- Initial treatment failure after 48-72 hours 2
- Severe immunocompromise 2
- Presence of systemic inflammatory response (fever, tachycardia, hypotension) 2
In these cases, add trimethoprim-sulfamethoxazole 160-800 mg twice daily or doxycycline 100 mg twice daily to the regimen. 1, 2
Essential wound management beyond antibiotics: 2
- Thorough irrigation and debridement to remove foreign material 2
- Consider imaging (ultrasound or plain radiographs) for retained fishhook fragments 2
- Update tetanus prophylaxis if indicated 2
- Close follow-up at 48-72 hours to assess for infection 2
Severe or Complicated Infections
For severe infections requiring hospitalization or IV therapy: 1, 2