Relationship Between <i>Streptococcus bovis</i>/<i>Streptococcus equinus</i> Complex and CRC; An Overview

Abstract

Streptococcus bovis/Streptococcus equinus complex (SBSEC) is a gram-positive coccus that belongs to group D of the Lancefield grouping. Most SBSEC strains have been characterized as commensal microorganisms, but some can cause severe infections, such as bacteremia and infective endocarditis (IE). Colorectal cancer (CRC) is the third most frequently diagnosed cancer and the third leading cause of cancer-related death. The connection between SBSEC bacteremia, endocarditis, and CRC is well recognized. The presence of CRC is directly linked to the stage of diagnosis, with stage I disease associated with a 5-year survival rate of 90.1%. Epidemiological research has revealed that in CRC patients, the colon is infected with SBSEC, even in the early stages, in ulcer tissues. However, the molecular mechanism of the SBSEC connection in CRC has not yet been identified. According to some reports, there are geographical discrepancies in SBSEC bacteremia, including the occurrence rate and origin of infection. For instance, Streptococcus bovis endocarditis is more prevalent in the European population than in the United States, and within Europe, there is variation between the North and South. In this review, we focus on the major virulence factors, diagnostic methods used to identify SBSEC isolates, and risk factors for CRC.