Clostridium difficile in mixed species biofilms: effect of Bifidobacterium bifidum CIDCA 5310

TREJO,F,M; HUGO, A. A.; CORDERO,G; MINNAARD, J.; PÉREZ, P.F.

Simposio; I International and Latin American Clostridium difficile Symposium; 2014

Clostridium difficile (CD) is a spore-forming microorganism responsible for pseudomembranous colitis. Bifidobacteria are potentially probiotic microorganisms that colonize the new born intestine. Several pathogens as CD have the ability to grow in biofilm. Reports have shown changes in the virulence associated to biofilm formation. The aim of present work was to evaluate the effect of the presence of Bifidobacterium bifidum (BB) on biofilm formation (BF), biological activity (BA) and viability of CD. CD strain 117 and BB CIDCA 5310 were cultured in anaerobic condition at 37 °C for 24 h in BHI broth supplemented with cysteine (0.05 % v/v). Pure cultures of CD (PC) or co-cultured with BB (CC) were seeded (OD600nm=0.05) in 24 well plates and incubated in anaerobic conditions at 37 °C. BF was evaluated by using crystal violet staining and expressed as RBF, defined as the ratio OD590 of sample/OD590 of control without bacteria BA was assessed on Vero cells by microscopic observation. We defined arbitrary units (AU) of biological activity as the inverse of the dilution that lead to 100 % of cell rounding. Viability was tested by plate counts. Biofilm formation of PC and CC reached a maximum at 24 h (RBF = 59.0 ± 17.8 and DO590 =71.6 ± 8.1 respectively) . A significant reduction (P