What is Finegoldia magna (formerly known as Peptostreptococcus magnus)?

From the Guidelines

Finegoldia magna infections should be treated with antibiotics effective against anaerobic bacteria, such as metronidazole or clindamycin, due to their efficacy against this gram-positive anaerobic bacterium 1. When considering the treatment of Finegoldia magna infections, it is essential to note that this bacterium is part of the normal human microbiota but can become an opportunistic pathogen, causing infections when it enters sterile body sites through trauma, surgery, or in immunocompromised individuals.

• F. magna is frequently isolated from skin and soft tissue infections, diabetic foot ulcers, surgical site infections, and bone and joint infections.
• It often appears in polymicrobial infections alongside other anaerobes or aerobic bacteria.
• The choice of antibiotic should be based on the severity of the infection and the presence of other pathogens. Some key points to consider in the treatment of F. magna infections include:
• Metronidazole (500mg orally three times daily for 7-14 days) is a commonly used antibiotic for the treatment of anaerobic infections, including those caused by F. magna 1.
• Clindamycin (300-450mg orally four times daily) is also effective against F. magna and can be used as an alternative to metronidazole.
• Amoxicillin-clavulanate (875/125mg twice daily) can be used to treat polymicrobial infections that include F. magna.
• Proper specimen collection and anaerobic culture techniques are essential for accurate diagnosis, as this slow-growing organism requires special conditions for laboratory identification. In severe cases of F. magna infection, combination therapy or intravenous antibiotics may be necessary to ensure adequate coverage against the bacterium and any other potential pathogens.
• The use of antibiotics should always be guided by susceptibility testing and local resistance patterns to ensure the most effective treatment outcome.
• It is also important to note that F. magna produces various virulence factors, including protein L, which binds immunoglobulins, and extracellular enzymes that contribute to tissue damage and help the bacterium evade host defenses 1.

From the Research

Characteristics of Finegoldia magna

• Finegoldia magna is an anaerobic gram-positive bacterium that can cause invasive human infections 2, 3, 4, 5.
• It is part of the human microbiota and can be found in the gastrointestinal and genitourinary tract, as well as on the skin and in the oral cavity 5.
• F. magna is known to be the most virulent among gram-positive anaerobic cocci, with a high pathogenic potential 4.

Antimicrobial Susceptibility

• F. magna is generally susceptible to most anti-anaerobic antimicrobials, including metronidazole, cefoxitin, linezolid, and chloramphenicol 4, 6.
• However, multidrug-resistant strains have been reported, and resistance to clindamycin and penicillin has been observed in some isolates 4.
• Antimicrobial susceptibility testing is crucial when treating F. magna infections, as the resistance pattern can vary from pathogen to pathogen and region to region 2, 4.

Clinical Infections

• F. magna can cause a range of mono- and polymicrobial infections, including skin and skin structure, bone and joint, infective endocarditis, necrotizing pneumonia, mediastinitis, and meningitis 5.
• It has also been implicated in cases of toxic shock syndrome, although this is rare 5.
• Orthopedic infections caused by F. magna are infrequent, but usually have good outcomes, with 80% of patients achieving complete clinical recovery 3.

Treatment

• The most commonly used antibiotic schemes for treating F. magna infections include amoxicillin, amoxicillin-rifampicin, and metronidazole 3.
• Antimicrobial susceptibility testing is recommended to guide treatment, especially when using antibiotics such as cefuroxime, cefepime, levofloxacin, rifampicin, doxycycline, or clindamycin 2.