Changes in Gut Microbial Diversity and Correlation with Clinical Outcome in Children with Acute Myeloid Leukemia Receiving Induction Chemotherapy.

Background: The gut microbiome affects human health, and patients with cancer are no exception. In those patients, intensive chemotherapy impairs gut barrier integrity, causing dysbiosis, bacterial translocation, and higher infection risk. Objectives: This prospective study, conducted at Children's Cancer Hospital in Egypt, profiles the microbiome of 29 pediatric patients with AML, and examines how induction chemotherapy and antibiotics affect their microbiome. Methods: Gut microbiome changes were evaluated before treatment (T1), then 7 (T2) and 21-28 days (T3) from induction start. Microbial DNA, extracted from rectal swabs or stool samples, was subjected to 16S rRNA amplicon sequencing, followed by bioinformatics and statistical analyses. Results: Treatment significantly decreased the richness and Shannon diversity of the gut microbiome and caused dysbiosis that was only partially restored at T3. Whereas Firmicutes remained the most abundant phylum throughout, Actinobacteria significantly decreased in abundance after treatment. Proteobacteria had their lowest abundance at T3, while Verrucomicrobacteria were relatively abundant at T1 but undetectable by T3. The abundance of Enterococcus and Klebsiella was associated with stool culture results, and the Proteobacteria-to-Firmicutes ratio was associated with treatment. Conclusions: Gut microbial diversity declined in patients during induction chemotherapy, with a strong association of microbial composition with stool culture results but not with bacteremia.