[10] Probiotics have in general been considered safe.[11] Prebiotics are non-digestible food ingredients that aid the growth of intestinal bacteria.[10] Synbiotics are a combination of a probiotic and a prebiotic. Although probiotic studies for TD prevention have produced conflicting results regarding efficacy, a recent meta-analysis suggests

that probiotics significantly prevent TD (RR = 0.85, 95% CI 0.79–0.91, p < 0.001).[11] In a previous study, Saccharomyces cerevisiae selleck inhibitor probiotic alone was not effective for TD prevention[12] but Saccharomyces boulardii reduced TD in a dose-dependent fashion (>1 million CFU/day) and in specific geographic areas (North Africa and Turkey).[12, 13] Probiotics that have been shown to reduce TD include Lactobacillus rhamnosus GG,[14, 15] Lactinex, Lactobacillus fermentum strain KLD (LF-KLD), Lactobacillus acidophilus (LA),[16] but the effect is not seen with all probiotics.[11] Given these conflicting results, new probiotics or combinations of probiotics and prebiotics need to be studied for the prevention of TD. We conducted a study to evaluate a synbiotic called Agri-King Synbiotic (AKSB) for TD prevention to see if it could

decrease antibiotic use if TD occurred. AKSB has three ingredients: the prebiotic fructo-oligosaccharide (FOS) and two organisms—Enterococcus faecium (microencapsulated SF68 called Ventrux ME 30) and S cerevisiae strain CNCM I 4444. Enterococcus faecium can compete with gram-negative organisms such as E coli.[17] AZD5363 Saccharomyces boulardii is shown to bind gram-negative bacteria.[18] A phase 1 study in humans showed that aminophylline AKSB was safe and increased stool enterococcal and saccharomyces growth within 3 days that washed out within 7 days of the last dose (unpublished data, data on file). We designed a single center, double-blind, placebo-controlled study comparing the prophylactic use of AKSB to placebo in healthy individuals

with the primary aim to determine whether AKSB can significantly reduce the incidence of TD in subjects traveling to a TD high-risk area. The secondary objectives were to: (1) demonstrate that AKSB reduces antibiotic use among travelers to these regions, (2) show that AKSB can shorten the number of days of TD, (3) examine the safety of AKSB in this population, (4) evaluate stool pathogen carriage after travel, and (5) examine the viability of AKSB capsules after subjects return from their trips. This randomized clinical trial was conducted between August 2002 and November 2006 at the Mayo Travel and Tropical Medicine Clinic (TTMC) in Rochester, MN, USA. Subjects aged 18 years or above and traveling for 5 to 30 days to a location considered at high risk for TD were eligible for the trial. The high-risk areas were defined as countries in the continents of Africa, South and Central America, and Asia.