Doxycycline's Effectiveness Against Finegoldia magna
Doxycycline is moderately effective against Finegoldia magna, with approximately 72% of isolates showing susceptibility, but antimicrobial susceptibility testing is mandatory before using it for targeted treatment of F. magna infections. 1
Antimicrobial Susceptibility Profile
Finegoldia magna (formerly known as Peptococcus magnus or Peptostreptococcus magnus) is an anaerobic gram-positive coccus that can cause various infections including:
- Skin and soft tissue infections
- Orthopedic infections
- Deep-seated abscesses
- Diabetic foot infections
- Periprosthetic joint infections
Recent research on F. magna susceptibility shows:
First-line options (nearly 100% susceptibility):
- Benzylpenicillin
- Amoxicillin/clavulanic acid
- Metronidazole 1
Variable susceptibility options:
Clinical Implications
When treating F. magna infections:
For empiric therapy: Choose benzylpenicillin, amoxicillin/clavulanic acid, or metronidazole as first-line options
For doxycycline use:
- Antimicrobial susceptibility testing is mandatory before using doxycycline for targeted therapy 1
- Doxycycline should not be relied upon empirically for F. magna infections
For polymicrobial infections:
- F. magna is often found in polymicrobial infections
- These cases may require more surgical procedures and have higher failure rates than monomicrobial infections 3
Important Considerations
- F. magna is part of the normal human microbiota but can cause opportunistic infections
- When isolated in pure culture from appropriate samples, species identification and antimicrobial susceptibility testing are crucial 4
- In the context of sexually transmitted infections, doxycycline is effective against many pathogens but may not provide reliable coverage for F. magna without susceptibility testing 5
Conclusion
While doxycycline has activity against many F. magna strains, it should not be considered a reliable empiric choice for these infections. When F. magna is suspected or confirmed, antimicrobial susceptibility testing is essential if considering doxycycline as treatment.