Changes in the intestinal microflora, especially an increase in the bacteroid population, are predictive factors for the development of diarrhea in patients on chemotherapy.

These data were obtained from a study in patients with non-Hodgkin's lymphoma receiving high-dose chemotherapy as a preparation for hematopoietic stem cell transplantation. This work is the first study demonstrating the relationship of changes in the microbiota occurring during chemotherapy with the development of diarrhea.

Changes in microflora occur, on average, 6 days before the onset of symptoms and may be the basis for the subsequent appointment of probiotics or other types of targeted therapy - these data were presented by scientists from the University of Nantes (University of Nantes, France) during the 53rd Interdisciplinary Conference on Antimicrobial Drugs and Chemotherapy (53rd Interscience Conference on Antimicrobial Agents and Chemotherapy - ICAAC).

Severe chemotherapy-induced diarrhea affects 20-30% of patients on chemotherapy and, in some cases, can be life-threatening. The pathophysiological mechanisms and the role of the intestinal microflora in the development of chemotherapy-induced diarrhea are not yet fully understood. Several studies have shown that the multiplication of the intestinal microflora is impaired during chemotherapy, but this does not cause diarrhea.

The study involved 6 patients with non-Hodgkin's lymphoma receiving chemotherapy as preparation for hematopoietic stem cell transplantation. On day 7 of chemotherapy, stool samples were collected which were subjected to V5-V6 analysis of the hypervariable regions of the 16S rRNA genes using Roche's 454 high performance pyrosequencing technique.

After an average delay of 13 days, 8 patients (22.2%) developed severe diarrhea. The metagenomic analysis identified 2 groups of patients - those who developed diarrhea and patients without this complication of chemotherapy. Patients who developed diarrhea had a higher number of Bacteroides microorganisms, and in patients without diarrhea, Escherichia coli prevailed.

Patients at risk could potentially receive a stool (or microbiota) transplant, which is taken from the patient before chemotherapy, and then the transplant is performed for patients with a high probability of developing diarrhea. The use of probiotics is another potential treatment option in this type of patient, however, a number of questions remain open, in particular, which bacteria, to whom and when to prescribe, as well as the safety aspects of the use of probiotics in immunocompromised patients.