The Role of Probiotics as Gastrointestinal Infections Treatment and Prophylaxis: A Review

1. Abstract Probiotics are products which contain microorganisms capable of supporting symbiotic relations with native microbiota of many environments. They are widely used and studied due to their capacity of improving biological systems’ overall health. Many hypothesis exist surrounding the mechanisms by which every microbe labelled as probiotic is the cause by which system health is enhanced by its presence. The aim of this review was to compile article’s data concerning the role of different combinations of probiotics used to treat and prevent gastrointestinal conditions, such as antibiotic-associated diarrhea, pseudomembranous colitis, Helicobacter pylori infections, oral, pharyngeal and Salmonella infections. In general, other than presenting excellent safety records, several probiotic combination registered in clinical trials could prove themselves capable of significantly preventing those infections and some proved to be capable to also treat them once established. The main challenge among the infections studies seems to be oral cavity infections, probably due to microbiota complexity. Nevertheless, probiotics seem to have good prospect for playing a major preventive and protective role in gastrointestinal infections with further investigation to gather sufficient evidence to base treatment protocols. 2. Introduction The very definition of probiotics was first produced in 1965 by Lilly and Stillwell [1] as bacteria who could increase other bacteria proliferation within biological systems, since then they have had their definition and usage broadly expanded. Currently updated by Hill et al. in 2014, the meaning of probiotics is now fit to describe microorganisms that can improve the health of a system when ingested in sufficient amount [2]. Therefore, such definition is intended to include their effects on many human systems concerning medical sciences, mainly by impacting the resident microbiota, intestinal epithelium cells, the immune system and cell-mediated response to infection and stress. The most studied species include Lactobacillus, Bifidobacterium, and Saccharomyces [3], but even prior to the first steps investigating probiotics’ potential, bacteria described as probiotic have been empirically added to dietary supplementation and foods due to the potential beneficial effects their action could produce for human health, and naturally clinical trials have been extensively conducted to measure and improve probiotic consumption and selection [4]. Further than that, many studies nowadays have provided evidence to support probiotics’ use as treatment and prophylaxis of a large array of infections, such as those produced by Helicobacter pylori, Clostridium difficile on the gastrointestinal tract, Streptococcus mutans on caries and periodontitis, many upper and lower respiratory tract infections, inflammatory bowel disease and diarrhea microbes, as well as other diseases. Not only typical presentation cases management have shown to be improved by probiotics use, but also multi-drug resistant bacteria infections could potentially be considered for probiotics use, amplifying their relevance since those are universally important public health issues. The major role probiotics could play, if proven to be effective, is