Streptococcus anginosus: a stealthy villain in deep odontogenic abscesses.

Odontogenic infections (OIs) occasionally spread to deep facial and neck tissues. Our study aimed to explore the role of Streptococcus anginous group (SAG) in these severe OIs. A retrospective study of patients aged ≥ 18 years who required hospital care for acute OI was conducted. We analysed data of OI microbial samples and recorded findings of SAG and other pathogens. These findings were compared with data regarding patients' prehospital status and variables of infection severity. In total, 290 patients were included in the analyses. The most common (49%) bacterial finding was SAG. Other common findings were Streptococcus viridans and Prevotella species, Parvimonas micra, and Fusobacterium nucleatum. Infection severity variables were strongly associated with SAG occurrence. Treatment in an intensive care unit was significantly more common in patients with SAG than in patients without SAG (p < 0.001). In addition, SAG patients expressed higher levels of C-reactive protein (p = 0.001) and white blood cell counts (p < 0.001), and their hospital stays were longer than those of non-SAG patients (p = 0.001). SAG is a typical finding in severe OIs. Clinical features of SAG-related OIs are more challenging than in other OIs. Early detection of SAG, followed by comprehensive infection care with prompt and careful surgical treatment, is necessary due to the aggressive behaviour of this dangerous pathogen.