Finegoldia is a genus of anaerobic bacteria that includes Finegoldia magna. This bacterium is typically a harmless part of the body’s natural microbe community, but it has the potential to become an opportunistic pathogen. When it enters a site of the body that is normally sterile, such as a deep wound or joint, it can cause serious infections. As a Gram-positive anaerobic coccus, F. magna is considered one of the more virulent species within this group of bacteria.
Characteristics and Normal Habitat
Finegoldia magna is classified as a Gram-positive coccus. It is a non-spore-forming bacterium and is obligately anaerobic, requiring an oxygen-free environment to grow and thrive.
The normal habitat for F. magna is as a member of the commensal flora of humans. It is found abundantly on the skin and on the mucosal surfaces of the respiratory, gastrointestinal, and genitourinary tracts. This widespread colonization means that a breach in the skin or mucosal barrier, such as from surgery or trauma, can allow the organism to access deeper tissues and cause infection.
Infections Caused by Finegoldia
When F. magna breaches the protective barriers of the body, it can be implicated in a wide range of infections. It is frequently isolated in cases of skin and soft tissue infections (SSTIs). The bacterium is also a common finding in chronic, non-healing wounds, such as diabetic foot ulcers and pressure ulcers, where it often forms complex communities known as biofilms.
Infections involving the bones and joints are another significant area where F. magna plays a role, including osteomyelitis and septic arthritis. The bacterium is particularly recognized as a cause of prosthetic joint infections. Furthermore, F. magna can cause systemic infections like bacteremia and has been associated with infections of the heart lining, known as endocarditis. These infections are often polymicrobial.
Difficulties in Identification
Since the bacterium is strictly anaerobic, specimens must be collected and transported in a manner that completely excludes oxygen. If proper conditions are not met, the organism will not grow, and the infection may be overlooked.
Even when proper anaerobic culturing is performed, F. magna is a slow-growing organism. Its identification can also be complicated by the fact that its physical appearance under a microscope can resemble other, less-virulent anaerobic cocci. For a faster or more definitive diagnosis, molecular methods like Polymerase Chain Reaction (PCR) are increasingly used to detect the bacterium’s genetic material.
Clinical Treatment Strategies
Management of Finegoldia magna infections combines surgical intervention with appropriate antibiotic therapy. Surgical procedures, such as drainage of abscesses and debridement, are often necessary to reduce the bacterial load. This is particularly important in infections involving bone or prosthetic devices.
Antibiotic selection focuses on drugs known to be effective against anaerobic bacteria. Commonly recommended first-line treatments include metronidazole, benzylpenicillin, and amoxicillin-clavulanate. Carbapenems are another class of antibiotics that show activity against F. magna and are sometimes used for more severe or complicated cases.
Treatment can be complicated by the bacterium’s ability to develop resistance. Acquired resistance to drugs like clindamycin and macrolides has been reported. Antimicrobial susceptibility testing (AST) is important, particularly if alternatives to the first-line drugs are considered or if the infection does not respond to initial therapy.