Infections caused by the emerging anaerobic surgical pathogen Finegoldia magna: review of 212 cases

Authors:
Aaron George, Hugo Bonatti, Joel Grunhut, Jonathan Adams, Junius Rosario, Pooja Ajith

Body of Abstract:
Background: Finegoldia magna (FM), previously referred to as Peptostreptococcus magnus, is a Gram-positive obligate anaerobic coccus (GPAC) that typically reside as part of the normal human skin and mucosal flora. They can act as an opportunistic pathogens being one of the most pathogenic GPAC. Severe infections such as endocarditis, pericarditis, necrotizing pneumonia and less common intraabdominal infections have been reported. FM has a higher propensity to cause soft tissue infections including necrotizing fasciitis.
Patients and Methods: Our institutional database was searched for all cases of FM infections during a 4-year period. Pathogens reported out as Peptostreptococcus magnus prior to introduction of MALDI-TOF in 2021 were reclassified as FM.
Results: A total of 261 isolates of FM in 212 patients (43% male) were identified. Median age was 54.1 (range 2.5 to 97.6) years). FM accounted for 37% of all 714 isolates of GPAC outnumbering Peptostreptococcus anaerobius (15%), Parvimonas micra (12%), Peptoniphilus asaccharolyticus (21%) and Anaerococcus prevotii (25%). For FM patients, rate of obesity was 60%, DM 39% and 34% of patients were active smokers. 93% of isolates were from drained abscesses or fluid collections and tissue biopsies, 4% were from wounds and 3% were recovered from blood cultures. 67% of specimens were sent by surgical services, 6% by medical teams, 11% by primary care and 16% cam from the emergency department. Infections were located at head&neck 3%, trunk 34%, upper extremity 3%, lower extremity 53% intraabdominal 4% with 3% bacteremia cases. Microscopy of 205 specimens revealed WBC in 76%, Gram positive cocci in 77%, Gram negative rods in 26% and Gram positive rods in 20%. In 24% FM was a single isolate, spectrum of pathogens isolated in addition to FM included staphylococci (29%), streptococci (17%), enterococci (3%), Gram negative rods (24%), anaerobes including other GPAC (50%), and yeast (1%). Staphylococcus aureus was the most common single co-infecting pathogens (27%) with 50% being MRSA. Treatment consisted of surgical drainage/debridement and antibiotics including Betalactms or clindamycin; outcome was in general favorable.
Conclusion: FM is an emerging pathogen mainly causing skin and soft tissue infections of the trunk and lower extremity. The exact role of FM in mixed infections is still unclear and warrants additional research.