Hematologic side effects are associated with prolonged antibiotic exposure in up to 34% of patients. Neutropenia, reported in 10-15% of patients, increases the risk of sepsis and death. Murine studies have established a link between the intestinal microbiota and normal hematopoiesis. We sought to identify predisposing factors, presence of microbiota-derived metabolites, and changes in intestinal microbiota composition in otherwise healthy pediatric patients who developed neutropenia after prolonged courses of antibiotics. In this multi-center study, patients with infections requiring anticipated antibiotic treatment of two or more weeks were enrolled. Stool samples were obtained at the start and completion of antibiotics and at the time of neutropenia. We identified 10 patients who developed neutropenia on antibiotics and 29 controls matched for age, sex, race, and ethnicity. Clinical data demonstrated no association between neutropenia and type of infection or type of antibiotic used; however intensive care unit admission and length of therapy were associated with neutropenia. Reduced intestinal microbiome richness and decreased abundance of Lachnospiraceae family members correlated with neutropenia. Untargeted stool metabolomic profiling revealed several metabolites that were depleted exclusively in patients with neutropenia, including members of the urea cycle pathway, pyrimidine metabolism and fatty acid metabolism that are known to be produced by Lachnospiraceae. Our study confirms a relationship between intestinal microbiota disruption and abnormal hematopoiesis and identifies taxa and metabolites likely to contribute to microbiota-sustained hematopoiesis. As the microbiome is a key determinant of stem cell transplant and immunotherapy outcomes, these findings are likely to be of broad significance.

Key Points

Neutropenia occurred in 17% of patients receiving prolonged antibiotic therapy.

We found no association between neutropenia and type of infection or class of antibiotic used.

Development of neutropenia after prolonged antibiotic treatment was associated with decreased prevalence of Lachnospiraceae and Lachnospiraceae metabolites such as citrulline.

The authors have declared no competing interest.

This study was funded by R01AI141716, R35HL155672, F31HL168921, F31HL147514, T32GM136554, and R31AI167538.

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The IRBs of Baylor College of Medicine and Vanderbilt University gave ethical approval for this work.

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