Streptococcus bovis infection and colorectal neoplasia: a meta-analysis

Aim A meta-analysis was conducted to determine the risk associated with Streptococcus bovis infection and the occurrence of colorectal neoplasia (CRN). The level of risk remains unknown. Method We conducted a search of MEDLINE, PubMed and EMBASE up to January 2014. We used a random-effects model to analyse the data. Results We identified 48 studies concerning three main topics: S. bovis septicaemia, S. bovis endocarditis and S. bovis faecal carriage. The total sample sizes were 1729, 807 and 1145, respectively; the 48 studies included 9 case-control studies and 39 case series. Overall, the presence of S. bovis infection was found to be significantly associated with the presence of CRN. Streptococcus bovis endocarditis showed the strongest association in analyses of case-control studies and case series (OR 14.54, 95% CI 5.66-37.35, test for heterogeneity I-2 = 43.53; event rate of 0.53, 95% CI 0.45-0.61, test for heterogeneity I-2 = 53.50). Similarly, S. bovis septicaemia was also associated with a high level of concurrence with CRN (OR 7.48, 95% CI 3.10-18.06, test for heterogeneity I-2 = 43.32; event rate 0.49, 95% CI 0.42-0.56, test for heterogeneity I-2 = 69.97). Patients with CRN were found to have a higher incidence of S. bovis in faeces upon stool culture (OR 2.52, 95% CI 1.14-5.58, test for heterogeneity I-2 = 69.17). Conclusion The meta-analysis showed a statistically significant association between the presence of S. bovis endocarditis or S. bovis septicaemia and CRN. Furthermore, there is a statistically significant increase in likelihood of finding S. bovis in the stool of individuals with CRN.