Systematic Review: Streptococcus salivarius and Its Role in Systemic Diseases

Background: Streptococcus salivarius, a predominant commensal bacterium of the human oral cavity, has traditionally been viewed as a beneficial member of the oral microbiota. However, emerging evidence suggests its dual role in both health and disease, with implications extending beyond the oral cavity to various systemic conditions. This systematic review aims to synthesize current evidence on the role of S. salivarius in systemic diseases, examining both its pathogenic potential and its therapeutic applications as a probiotic. Methods: A comprehensive literature search was conducted across multiple databases including PubMed, Scopus, and Web of Science for studies published up to ۲۰۲۵. Search terms included "Streptococcus salivarius," "systemic disease," "bacteremia," "endocarditis," "probiotic," "immune modulation," and "systemic inflammation." Both clinical studies and relevant preclinical research were included. Results: The evidence reveals a paradoxical role for S. salivarius. On one hand, it can act as an opportunistic pathogen, particularly in immunocompromised hosts, causing bacteremia and infective endocarditis. On the other hand, specific strains (notably K۱۲, M۱۸, and ۲۴SMB) have demonstrated significant probiotic benefits, including reduction of respiratory tract infections, modulation of immune responses, and potential protection against viral infections including COVID-۱۹. The concept of "oral-systemic dysbiosis" has emerged as a framework for understanding how oral microbial disruption contributes to systemic inflammatory and metabolic disorders. Conclusion: S. salivarius exhibits a strain-specific duality in its relationship with human health. While certain strains possess pathogenic potential in vulnerable populations, well-characterized probiotic strains offer promising therapeutic applications for systemic conditions. Further research is needed to elucidate strain-specific mechanisms and establish standardized protocols for clinical use.

کلیدواژه ها:

Streptococcus salivarius ، BLIS K۱۲ ، Oral-systemic dysbiosis ، Opportunistic pathogen ، Viridans streptococci ، Inflammation ، Mucosal immunity