Liver Abscess due to Streptococcus intermedius Bacteremia and Its Association with Colonic Carcinoma: Is Bacteremia with Streptococcus intermedius an Alert for Colonic Carcinoma?

Liver abscess caused by some kinds of Streptococcus group such as Streptococcus bovis group has been recognized to associate with colorectal cancer. Streptococcus milleri group with liver abscess has not been received much attention in this point of view. Here, we report the case of a 63-year-old man who developed liver abscess with S. intermedius, which belongs to the S. milleri group. We confirmed that this case was accompanied by cecal carcinoma by colonoscopy. The tumor was a pathological lead point of intussusception of cecum. On the 26th day, open right hemicolectomy was performed. In this case, bacterial endophthalmitis was a complication due to bacteremia. The patient underwent ophthalmic surgery on the 98th day. Research investigating 16S rRNA of the mucosal colon microbiome reported that the S. intermedius gene was upregulated in patients with colorectal carcinoma. It is recommended that liver abscess with S. intermedius bacteremia should alert the clinician about the risks of carcinoma of the colon and abscess formation in distant organs. We here list the case reports of liver abscess caused by Streptococcus other than S. bovis group, which was associated with colonic carcinoma, and suggest the need for further research about S. milleri group.