Published online May 14, 2015. doi: 10.3748/wjg.v21.i18.5663
Peer-review started: October 19, 2014
First decision: December 11, 2014
Revised: December 22, 2014
Accepted: February 5, 2015
Article in press: February 5, 2015
Published online: May 14, 2015
Processing time: 213 Days and 16.7 Hours
AIM: To prospectively examine the association between presence of Streptococcus bovis (S. bovis) in colonic suction fluid and the endoscopic findings on colonoscopy.
METHODS: From May 2012 to March 2013, 203 consecutive patients who underwent colonoscopy for any reason were enrolled in the study. Exclusion criteria included: antibiotic use in the previous month, age younger than 18 years, and inadequate preparation for colonoscopy. The colonoscopy was performed for the total length of the colon or to the occluding tumor. The endoscopic findings were registered. Samples were obtained proximal to the colonoscopic part of the suction tube from each patient and sent to the clinical microbiology laboratory for isolation and identification of S. bovis. Samples were incubated in enrichment media with addition of antibiotic disks for inhibition of growth of Gram-negative rods. The samples were seeded on differential growth media; suspected positive colonies were isolated and identified with Gram staining, catalase, and pyrrolidonyl arylamidase tests, and further identified using a VITEK2 system. Statistical analyses were performed using the Student’s t and χ2 tests.
RESULTS: Of the 203 patients recruited, 49 (24%) patients were found to be S. bovis carriers; of them, the endoscopic findings included: 17 (34.7%) cases with malignant tumors, 11 (22.4%) with large polyps, 5 (10.2%) with medium-sized polyps, 6 (12.2%) with small polyps, 4 (8.1%) with colitis, and 6 (12.2%) normal colonoscopies. Of 154 patients found negative for S. bovis, the endoscopic findings included: none with malignant tumors, 9 (5.8%) cases with large polyps, 11 (7.1%) with medium-sized polyps, 26 (16.9%) with small polyps, 7 (4.5%) with colitis, and 101 (65.6%) normal colonoscopies. S. bovis (Gram-positive coccus) is considered part of the normal intestinal flora. There is an association between S. bovis bacteremia and colonic neoplasia. It is not well understood whether the bacterium has a pathogenetic role in the development of neoplasia or constitutes an epiphenomenon of colorectal neoplasms. There was a clear relationship between positivity for S. bovis in colonic suction fluid and findings of malignant tumors and large polyps in the colon.
CONCLUSION: There is an association between S. bovis bacteremia and malignant colonic lesions; this should prompt for development of a reliable screening method for advanced colonic lesions.
Core tip: Currently, there is no available noninvasive, efficient, predictive tool for screening patients in high-risk populations for the purpose of colonoscopy examination. In this prospective study, we show a clear association between the presence of Streptococcus bovis in colonic suction fluid and findings of malignant tumors and large polyps during colonoscopy examination. Stool samples in different forms can be used as screening material for detection of the population at risk for advanced colorectal lesion. This may be preferable to repeated colonoscopy for surveillance in patients who underwent treatment of advanced colonic lesions by endoscopy or surgery.