The first description of colorectal cancer occurring in association with S bovis
bacteraemia was attributed to Mccoy and Mason in 1951. S bovis
is known to be a causal bacterium of endocarditis and accounts for approximately 15% of bacterial endocarditis.1
Many reports regarding an association between endocarditis or bacteraemia due to S bovis
and colorectal cancer have been published.1,2
The patients with endocarditis caused by S bovis
more frequently suffered from colorectal cancer than those patients infected with other causal bacteria.1
Burns et al5
reported that patients with colorectal cancer have S bovis
in their faeces more frequently than healthy people. Klein et al2
reported that the faecal carrier rate of S bovis
was significantly higher in patients with colorectal cancer or inflammatory bowel disease than in controls, while an association between S bovis
and the colorectal cancer could not be recognised by Dubrow et al
It has been proposed that S bovis
could readily survive in the intestines of patients with colorectal neoplasms and that S bovis
itself might produce carcinogens.2
Kampe et al7
considered that colorectal neoplasms have the portal site for the entry of S bovis
. More recently, it was reported that S bovis
and antigens extracted from the bacterial cell wall acted as a promoter of early pre-neoplastic lesions in the colon of rats.8
Moreover, the antigens extracted from S bovis
have been shown to induce interleukin 8 (IL-8), prostaglandin E2 (PG-E2), and cyclo-oxygenase 2 (COX-2) production by using human colorectal cancer cells (Caco-2 cells) and mucosal tissue of rats.9
BLP is a preparation of live L casei
Shirota (freeze dried bacterium), containing 1×1010
bacteria/g, which are resistant to acid, digestive juice and bile acid. L casei
reaches the colon alive, and improves gastrointestinal flora by raising Bifidobacterium
and reducing Enterobacteriaceae
Our case appears to confirm the effect of BLP on Bifidobacterium
. BLP also suppresses harmful bacteria such as S bovis.
The mechanism of this effect is suspected to depend on the antibacterial activity of lactic acid and the promotion of an immune reaction induced by BLP, such as the activation of macrophages and the production of interferon.10
In conclusion, we were able to reduce the proportion of S bovis in the patient’s faecal flora by treating him with BLP for 6 years, and this effect continued for at least 2 years after BLP administration was stopped. This is the first report of successful manipulation of S bovis in the faecal flora. However, further studies will be necessary to determine whether any benefit is derived from the reduction of S bovis in the flora.
- The case is presented of a patient with colon adenoma, who had a high proportion of Streptococcus bovis in his faecal flora.
- Endocarditis and bacteraemia due to S bovis infection are associated with colorectal neoplasms.
- The patient was treated with Lactobacillus casei Shirota strain (L casei) which resulted in a reduction in the proportion of S bovis (from 43% down to 9%), and this effect was continued after the treatment was stopped.
- This is the first report of successful manipulation of S bovis in the faecal flora.