We analyzed one assertion about fecal microbiota transplantation in critically ill sepsis patients on antibiotics, and it suggests that in 60% of recipients, the gut microbiota shifts from being dominated by Parabacteroides to being dominated by Bacteroides — aligning with the microbial profile of the donor [1]. This is the only piece of evidence we’ve reviewed so far, and it does not contradict this observation. The shift appears to happen in a majority of cases, but we don’t know how long it lasts, whether it’s consistent across all patients, or if factors like antibiotic type, illness severity, or donor selection influence the outcome. We also don’t have data on whether this change affects patient recovery, infection risk, or other health outcomes. The evidence we’ve reviewed leans toward the idea that fecal microbiota transplantation can reshape the gut bacteria in this specific group of patients, but it’s based on a single observation without comparison groups or long-term tracking. Because we only have one assertion and no studies that challenge it, we can’t say how common or reliable this shift is across larger or more diverse populations. It’s possible this result is unique to the conditions of the original observation. More research would be needed to understand how often this happens, why it occurs in some but not all patients, and what it might mean for their health. For now, if someone is considering this treatment, it’s worth knowing that in some cases, the gut bacteria may begin to resemble the donor’s — but whether that’s helpful, harmful, or neutral remains unclear based on what we’ve seen so far.