AUTHOR=Périchon Bruno , Lichtl-Häfele Julian , Bergsten Emma , Delage Vincent , Trieu-Cuot Patrick , Sansonetti Philippe , Sobhani Iradj , Dramsi Shaynoor 

TITLE=Detection of Streptococcus gallolyticus and Four Other CRC-Associated Bacteria in Patient Stools Reveals a Potential “Driver” Role for Enterotoxigenic Bacteroides fragilis

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2022.794391

DOI=10.3389/fcimb.2022.794391

ISSN=2235-2988

ABSTRACT=<sec><title>Purpose</title><p><italic>Streptococcus gallolyticus</italic> subspecies <italic>gallolyticus</italic> (<italic>SGG</italic>) is an opportunistic pathogen causing invasive infections in the elderly often associated with colon neoplasia. The prevalence of <italic>SGG</italic> in the stools of patients with normal colonoscopy (control) was compared with patients with colorectal adenomas (CRA) or with carcinomas (CRC) from stages I to IV. The presence of the <italic>pk</italic>s island encoding colibactin as well as other CRC-associated bacteria such as toxicogenic <italic>Bacteroides fragilis</italic>, <italic>Fusobacterium nucleatum</italic>, and <italic>Parvimonas micra</italic> was also investigated.</p></sec><sec><title>Patients and Methods</title><p>Fecal samples collected in France between 2011 and 2016 from patients with normal colonoscopy (<italic>n</italic> = 25), adenoma (<italic>n</italic> = 23), or colorectal cancer at different stages (<italic>n</italic> = 81) were tested by PCR for the presence of <italic>SGG</italic>, <italic>B. fragilis</italic>, <italic>F. nucleatum</italic>, <italic>P. micra</italic>, and the <italic>pks</italic> island. Relative quantification of <italic>SGG</italic>, <italic>F. nucleatum</italic>, and <italic>P. micra</italic> in stools was performed by qPCR.</p></sec><sec><title>Results</title><p><italic>SGG</italic> prevalence was significantly increased in the CRC group. Our results also revealed i) a strong and significant increase of toxinogenic <italic>B. fragilis</italic> in patients with early-stage adenoma and of <italic>pks</italic> island at late-stage CRC and ii) increased levels of <italic>F. nucleatum</italic> and <italic>P. micra</italic> in the stools of CRC patients. Furthermore, the simultaneous detection of these five bacterial markers was only found in CRC patients.</p></sec><sec><title>Conclusions</title><p>Our results indicate that the prevalence or relative levels of CRC-associated bacteria vary during CRC development. Among them, <italic>B. fragilis</italic> (<italic>bft</italic>+) was singled out as the sole pathobiont detected at the early adenoma stage.</p></sec>