The S. bovis group includes S. equinus, S. gallolyticus, S. infantarius, and other closely related species; they are the nonenterococcal group D streptococci. Members of this group are esculin positive, 6.5% salt negative, sorbitol negative and produce acetoin. Isolates from the S. bovis group are most frequently encountered in blood cultures from patients with colon cancer. However, S. bovis group organisms (especially S. gallolyticus subsp. gallolyticus and S. infantarius subsp. coli) have been associated with endocarditis (3). Although infection with S. bovis group organisms occurs with higher frequency in adults than in pediatric patients, these organisms have been reported to cause neonatal sepsis and meningitis (20).[citation needed]
The main portal of entry for human infection of S. bovisbacteremia is the
gastrointestinal tract, but in some cases, entry is through the urinary tract, the hepatobiliary tree, or the oropharynx.[11]
S. bovis has long been associated with
colorectal cancer;[6][15] however, not all genospecies are associated equally. A 2011 meta-analysis on the association between S. bovis biotypes and colonic adenomas/carcinomas revealed that patients with S. bovis biotype I infection had a strongly increased risk of having colorectal cancer (pooled odds ratio: 7.26; 95% confidence interval: 3.94–13.36), compared to S. bovis biotype II-infected patients.[16] This analysis suggests S. bovis should no longer be regarded as a single bacterial entity in clinical practice. Only Streptococcus gallolyticus (S. bovis biotype I) infection has an unambiguous association with colonic adenomas/carcinomas (prevalence range: 33–71%) that markedly exceeds the prevalence of colonic (pre-)malignancies in the general population (10–25%). Nevertheless, research has not yet determined that S. gallolyticus is a causative agent of colorectal cancer, or if pre-existing cancer makes the
lumen of the large intestine more hospitable to its outgrowth.[17]
Ruminal effects
When ruminants consume diets high in
starch or
sugar, these easily fermentable carbohydrates promote the proliferation of S. bovis in the rumen. Because S. bovis is a lactic acid bacterium, fermentation of these carbohydrates to
lactic acid can cause a dramatic decline in ruminal pH, and subsequent development of adverse conditions such as ruminal acidosis or feedlot bloat.[8][9]
^
abAsanuma N, Hino T (2002). "Regulation of fermentation in a ruminal bacterium, Streptococcus bovis, with special reference to rumen acidosis". Animal Science Journal. 73 (5): 313–325.
doi:
10.1046/j.1344-3941.2002.00044.x.