the effects of commercial probiotics on biological properties of enterococci in colon carcinoma cell culture

Background: the interactions between dysbiosis of gut microbiota and the development of colorectal cancers are well known. we investigated the effects of three different commercial probiotics, purchased from pharmacies, on several biological properties of enterococci (vancomycin-resistant “vre” and vancomycinsusceptible “vse”) in colon adenocarcinoma cell culture (ht-29). methods: cell-free supernatants (cfss) were prepared after isolating probiotic strains (bifidobacterium lactis, saccharomyces boulardii, and bacillus clausii). bacterial growth was detected spectrophotometrically after three, six, and 24 hours of incubation. adhesion and invasion assays were performed using the colony counting method. biofilm formation was performed using microtiter plate assay. graphpad prism software, version 5, was used for analysis. results: after 24 hours incubation in culture medium, all three probiotics increased (p<0.001) the growth of vre and vse. bacterial growth was also increased in cell culture in the presence of probiotics (p<0.001). adhesion of both enterococci was reduced (p<0.001) by all probiotics. the invasion and biofilm formation were varied according to strains and probiotics tested. conclusion: the effects of probiotics may vary depending on the specific strains used. furthermore, during probiotic usage, potential risk of enhanced pathogenicity under certain circumstances, especially in immune suppression should be considered.