• Mouth microbes
• Mortality risk
What is already known on this topic
Changes in gut microbiota composition caused by drugs and radiation can promote graft-versus-host disease, a fatal immune condition that occurs after transplant procedures. This condition leads to poor outcomes of hematopoietic stem cell transplantation, which is used to treat people with certain cancers of the blood or bone marrow and is often preceded by chemotherapy, radiotherapy, and antibiotics.What this research adds
Researchers determined the tongue microbiota composition of 45 people with hematological disorders on the day of hematopoietic stem cell transplantation. Transplant recipients had a less diverse microbiota than healthy people. Of 146 bacterial families identified in the microbiota of recipients, 34 did not correspond to bacteria inhabiting the mouth of healthy individuals. In particular, Staphylococcus haemolyticus and Ralstonia pickettii were associated with a higher risk of mortality during the follow-up period.Conclusion
The study shows that the mouth of hematopoietic stem cell transplantation recipients is colonized by an altered microbiota on the day of transplantation. The findings also suggest that specific mouth-dwelling bacteria could be used to predict transplant outcomes.
Changes in gut microbiota composition caused by drugs and radiation can promote graft-versus-host disease, a fatal immune condition that occurs after transplant procedures. This condition leads to poor outcomes of hematopoietic stem cell transplantation, which is used to treat people with certain cancers of the blood or bone marrow and is often preceded by chemotherapy, radiotherapy, and antibiotics. Now, researchers have shown that the mouth of hematopoietic stem cell transplantation recipients is colonized by an altered microbiota on the day of transplantation.
The findings, published in PLOS Pathogens, suggest that specific mouth-dwelling bacteria could be used to predict the outcome of hematopoietic stem cell transplants.
Yoshihisa Yamashita at Kyushu University in Fukuoka, Japan, and his colleagues analyzed the tongue microbiota composition of 45 people with hematological disorders, such as blood cell cancers, on the day of hematopoietic stem cell transplantation.
Mouth microbes
Transplant recipients had a less diverse microbiota than healthy people. Bacteria such as Streptococcus, Prevotella, and Neisseria were present at lower abundances in transplant recipients compared to healthy individuals.
Most of the microbiota on the tongue of recipients were composed of common mouth bacteria, including Rothia mucilaginosa, Granulicatella adiascens, and Veillonella dispar. However, non-oral bacteria were predominant in the mouth of some recipients: for example, Staphylococcus haemolyticus accounted for more than 40% of the mouth microbiota in three patients.
Mortality risk
Of 146 bacterial families identified in the microbiota of transplant recipients, 34 did not correspond to bacteria inhabiting the mouth of healthy individuals. What’s more, the presence of Staphylococcus haemolyticus and Ralstonia pickettii was associated with a higher risk of mortality during the follow-up period.
“This study demonstrated that the indigenous oral microbiota of [hematopoietic stem cell transplantation] recipients was disrupted at the time point of stem cell transplantation after receiving intensive chemotherapy, radiation, and antibiotics,” the researchers say. “These results suggest that careful attention should be given to the bacterial composition of the disrupted oral microbiota in [hematopoietic stem cell transplantation] recipients.”
