Probiotics to counteract biofilm-associated infections: promising and conflicting data

Altered bowel flora is currently thought to play a role in a variety of disease conditions, and the use of Bifidobacterium spp. and Lactobacillus spp. as probiotics has been demonstrated to be health-promoting, even if the success of their administration depends on the applied bacterial strain(s) and the targeted disease. In the last few decades, specific probiotics have been shown to be effective in the treatment or the prevention of acute viral gastroenteritis, pediatric post-antibiotic-associated diarrhea, some pediatric allergic disorders, necrotizing enterocolitis in preterm infants, inflammatory bowel diseases and postsurgical pouchitis. The potential application of probiotics is continuously widening, with new evidence accumulating to support their effect on the prevention and treatment of other disease conditions, including several oral diseases, such as dental caries, periodontal diseases and oral malodor, as well as genitourinary and wound infections. Considering the increasingly widespread ability of pathogens to generate persistent biofilm-related infections, an even more attractive proposal is to administer probiotics to prevent or counteract biofilm development. The response of biofilm-based oral, intestinal, vaginal and wound infections to probiotics treatment will be reviewed here in light of the most recent results obtained in this field. There is both conflicting and promising evidence that administration of “good” bacteria, or probiotics, prevents biofilm-related infections. Despite data showing that probiotics contribute to maintaining a healthy gut, a review by Claudia Vuotto and colleagues from the IRCCS Fondazione Santa Lucia, Rome, Italy, suggests that the effects of probiotics on other conditions in which bacteria grow as aggregates in biofilms are unclear. Several lactic-acid producing bacteria benefit the host by reducing the growth of toxic bacteria and stimulating an immune response. However, for the treatment of biofilm-associated oral diseases, genitourinary and wound infections, the effects are highly dependent on the biofilm's composition and the probiotic strain that is used. Further studies are required to identify the most effective strains to eradicate such biofilms and tackle one of the most urgent challenges in anti-bacterial drug development.