AIM:To investigate the effect of Lactobacillus-containing commercially available probiotic formulations in Germany during antibiotic treatment with an analysis of cost-efficiency.METHODS:In an observational study,we analyzed the frequency of bowel movements from 258 patients with infections in a primary care hospital in western Germany;107 of the patients were offered a probiotic drink containing at least 10 billion cultures of Lactobacillus casei DN 114001 b.i.d.The economic analysis was based on the costs of patient isolation vs preventive intake of probiotics.In a second pilot study,two commercially available probiotic drinks with different Lactobacillus casei strains were directly compared in 60patients in a randomized controlled fashion.RESULTS:In the first study,the incidence of antibioticassociated diarrhea(AAD)was significantly reducedin the intervention group(6.5%vs 28.4%),and the duration of AAD in days was significantly shorter(1.7±1.1 vs 3.1±2.1).Higher age and creatinine and lower albumin were identified as risk factors for AAD.Ampicillin was the antibiotic with the highest rate of AAD(50%)and with the greatest AAD reduction in the probiotic group(4.2%,relative risk reduction 92%).The economic analysis showed a cost advantage of nearly60000€/year in a department of this size.The second study confirmed the preventive effect of the drink with Lactobacillus casei DN114001;however,there were no advantages found for the other tested probiotic drink containing Lactobacillus casei Shirota.CONCLUSION:In contrast to a drink containing Lactobacillus casei Shirota,a commercially available probiotic drink containing Lactobacillus casei DN 114001 costefficiently reduces the prevalence of AAD during antibiotic treatment. AIM: To investigate the effect of Lactobacillus-containing commercially available probiotic formulations in Germany during antibiotic treatment with an analysis of cost-efficiency. METHODS: In an observational study, we analyzed the frequency of bowel movements from 258 patients with infections in a primary care hospital in western Germany; 107 of the patients were offered a probiotic drink containing at least 10 billion cultures of Lactobacillus casei DN 114001 bidThe economic analysis was based on the costs of patient isolation vs preventive intake of probiotics. In a second pilot study, two commercially available probiotic drinks with different Lactobacillus casei strains were directly compared in 60 patients in a randomized controlled fashion .RESULTS: the first study, the incidence of antibioticassociated diarrhea (AAD) was significantly reduced in the intervention group (6.5% vs 28.4%), and the duration of AAD in days was significantly shorter (1.7 ± 1.1 vs 3.1 ± 2.1) .Higher age and creatinine and lower albumin were identified as risk factors for AAD. Ampicillin was the antibiotic with the highest rate of AAD (50%) and with the greatest AAD reduction in the probiotic group (4.2%, relative risk reduction 92%). The economic analysis showed a cost advantage of nearly 60000 € / year in a department of this size. second study confirmed the preventive effect of the drink with Lactobacillus casei DN114001; however, there were no advantages found for the other tested probiotic drink containing Lactobacillus casei Shirota. CONCLUSION: In contrast to a drink containing Lactobacillus casei Shirota, a commercially available probiotic drink containing Lactobacillus casei DN 114001 costefficiently reduces the prevalence of AAD during antibiotic treatment.