Finegoldia magna (formerly Peptostreptococcus magnus): an overlooked etiology for toxic shock syndrome?

Finegoldia magna is an anaerobic Gram positive coccus, previously classified as Peptostreoptococcus magnus. It is normal flora of the gastrointestinal and genitourinary tract, and can be isolated from skin and the oral cavity and is often regarded as a contaminant in cultures. As the most frequently isolated anaerobic coccus, it is implicated in a range of mono- and polymicrobial infections, including skin and skin structure, bone and joint (native and prosthetic joints), infective endocarditis (native and prosthetic valves), necrotizing pneumonia, mediastinitis and meningitis. Recently, whole genome sequencing furthered the understanding of the pathogenicity of this organism by elucidating both chromosomally encoded and mobile plasmid mediated virulence factors. Although no cases of toxic shock syndrome have been attributed to F. magna, we present a case of a fatal monomicrobial F. magna bacteremia and hypothesize that superantigen activity, mediated via Protein L binding the variable domain of the κ light chains of IgG, resulted in the syndrome observed in our patient. Additionally, we suspect the overall significance of this pathogen is underestimated and with more sensitive detection methods, this organism will be identified more frequently in clinical cultures and associated with true infection.