Streptococcus anginosus orchestrates antibacterial potential of NETs facilitating survival of accompanying pathogens

Abstract

Streptococcus anginosus is considered an emerging opportunistic pathogen causing life-threatening infections, including abscesses and empyema. Noticeably, clinical data revealed that S. anginosus also constitutes an important component of polymicrobial infections. Here, we showed for the first time that S. anginosus inactivates the antibacterial potential of neutrophil extracellular traps (NETs). The process is determined by a cell wall-anchored nuclease referred to as SanA, which high expression dominates in clinical strains isolated from severe infections. Nuclease activity protects S. anginosus against the antibacterial activity of NETs, supporting at the same time the survival of coexisting highly pathogenic species of Enterobacteriales. Obtained data suggest that SanA nuclease should be recognized as a critical S. anginosus virulence factor determining severe monospecies purulent infections but also shielding other pathogens promoting the development of polymicrobial infections.

Keywords: Coinfection; DNases; Enterobacteriales; NETs; Neutrophils; Streptococcus anginosus; Virulence factor.