Bifidobacterium bifidum CIDCA 5310 antagonize virulence factors associated to Clostridium difficile. Study in vitro and in vivo models.

TREJO, FM; DE ANTONI GL ; PÉREZ, PF.

Simposio; I International and Latin American Clostridium difficile Symposium: epidemiology, pathogenesis, prevention and treatment.; 2014

Clostridium difficile, is an important etiological agent of antibiotic-associated colitis and diarrhea. The main virulence factors are two protein toxins: TcdA and TcdB. Clinical evidence suggest that probiotics such as Bifidobacterium and Lactobacillus constitute an alternative approach to prevent/treat C. difficile associated diarrhea (CDAD). However, mechanisms by which those bacteria exert their protective effect have not yet completely known.The present work aimed to assess the correlation between in vitro and in vivo results of studies of the antagonism of C. difficile by B. bifidum CIDCA 5310. In vitro: biological activity of supernatants (SN) obtained from C. difficile pure cultures or co cultures with Bifidobacterium was evaluated on Vero cells. Biological activity was defined as SN concentration detaching 50% of cells (DD50). Toxin concentrations were measured by using monoclonal antibodies (dot blot). In vivo: from day 1 (d1) to the end of the experiment female hamsters received viable bifidobacteria (109 CFU/animal per day) or drinking water alone (control). At d7 3 mg/animal were administered and at d11 100 µl of vegetative C. difficile 117 suspension (109 CFU/animal) wre administered. Infection markers were: diarrhea, enterocolitis and animals death. Cecal contents were assayed for biological activity on Vero cells and tissues were studied by haematoxilin-eosin staining.Biological activity and toxin levels in supernatants of co-cultures were significantly reduced with no impairment of the ability of clostridium growth. These results correlated with the ability of strain CIDCA 5310 to protect hamsters in a model of C. difficile infection. Enterocolitis (EC) and death ratio (M)) were 11/13 and 4/13 in control group whereas these values decreased significantly in the bifidobacteria-treated group (EC=3/13, M=0/13). In addition, DD50 in cecal contents was 0,6 ± 0,5 and 2,9 ± 1,2 for control and bifidobacterias-treated animals. Our results showed for the first time the correlation between in vitro and in vivo effects of a selected strain of Bifidobacteriun with potential application in the prophylaxis/treatment of CDAD.