Abstract

The human bowel contains a large and dynamic bacterial population (more than 500 species of bacteria). Some intestinal bacteria such as Streptococcus bovis,Enterococcus spp., Bacteroides fragilis and Clostridium perfringens have previously been suggested to be implicated in the promotion of colon carcinogenesis probably through the conversion of mutagen metabolites. In this study 30 patients with colorectal cancer confirmed by colonoscopy examination and pathological methods were evaluated. In control group, 30 healthy people matched by sex and age with the patient group were identified. Fecal samples were collected from patient and control groups and were cultured in specific and non-specific culture media (aerobic and anaerobic conditions) organisms were isolated by microbial and biochemical methods. S. boviswas the predominant fecal microbial flora in 9 of the patients (39.1%) and 6 of the control group (26.1%) P = 0.657. Entrococcus spp. was the predominant fecal microbial flora in 6 of the patients (26.1%) and 2 of the control group (8.7%) P=0.657. Bacteroides fragilis was the predominant fecal microbial flora in 8 of the patients (21.6%) and 2 of the control group (5.4%) P= 0.062 C. perfringens was the predominant fecal microbial flora in 11 of the patients (29.7%) and 16 of the control group (43.2%) P=0.062. Based on our sample size in this study, the results, when analyzed using Fisher statistical analysis, showed that the incidences of fecal S. bovis, Enterococcus, B. fragilis andC.perfringens in colorectal cancer were not significantly higher than healthy people.

Key words: Colorectal cancer, fecal microbial flora, Streptococcus bovis, Enterococcusspp., Bacteroides fragilis, Clostridium perfringens.