Personalized microbiome biotherapeutics may tailor donor, product, recipient, ecological conditioning, or monitoring. This review assessed human evidence across recurrent Clostridioides difficile infection (CDI), cancer immunotherapy, ulcerative colitis, and multidrug-resistant organism (MDRO) decolonization, distinguishing validated personalization from protocol standardization.

PRISMA 2020 guided a narrative synthesis. PubMed/MEDLINE, CENTRAL, ClinicalTrials.gov, regulatory sources and citation searching were searched to 2 February 2026. Two reviewers screened records and extracted data independently. Risk of bias and certainty of evidence were appraised descriptively rather than through formal RoB 2, ROBINS-I or GRADE procedures, and no meta-analysis was performed. The review was not prospectively registered.

Twenty-seven unique studies (28 reports) were retained: 7 recurrent-CDI, 8 oncology, 7 ulcerative-colitis, and 5 MDRO studies. Four used prospective donor or protocol selection beyond routine criteria, 14 were personalization-enabling, and 9 were non-personalized comparators. Standardized products produced the most consistent recurrent-CDI benefit. Responder-donor FMT and defined microbial consortia showed signals in oncology, ulcerative-colitis results varied, and MDRO evidence remained limited. No validated patient-level donor-recipient matching algorithm was found.

Evidence supports indication- and protocol-level tailoring, not routine patient-specific matching. Prospective comparative trials should prespecify allocation rules, analytical validation, clinically important outcomes, and safety surveillance.