This clinical trial is focused on preventing Clostridium difficile infections in patients who are undergoing a medical procedure called allogeneic hematopoietic stem cell transplantation. This procedure involves replacing a patient’s blood-forming cells with those from a donor. The study will use a medication called vancomycin, which is an antibiotic, to see if it can help prevent these infections. Some patients will receive vancomycin, while others will receive a placebo, which looks like the medication but does not contain the active ingredient.

The purpose of the study is to evaluate if taking oral vancomycin can effectively prevent Clostridium difficile infections in these patients. Participants in the study will be randomly assigned to receive either vancomycin or a placebo. The study will be conducted in a double-blind manner, meaning neither the participants nor the researchers will know who is receiving the actual medication or the placebo. This helps ensure that the results are not biased.

Throughout the study, participants will be monitored for signs of Clostridium difficile infection, which can cause symptoms like diarrhea. The study will last for several weeks, and participants will be observed from the time they are included in the study until they are discharged from the hospital or until the end of the treatment period. The study aims to provide valuable information on whether vancomycin can be a useful preventive treatment for these infections in patients undergoing this type of transplantation.