The intestinal bacterial flora of febrile neutropenic patients has been found to be significantly diverse. However, there are few reports of alterations of in adult
acute myeloid leukemia (AML) patients. Stool samples of each treatment-naïve AML patient were collected the day before initiation of
induction chemotherapy (pretreatment), on the first date of neutropenic
fever and first date of bone marrow recovery.
Bacterial DNA was extracted from stool samples and bacterial
16s ribosomal RNA genes were sequenced by next-generation sequencing. Relative abundance, overall richness, Shannon's diversity index and Simpson's diversity index were calculated. No antimicrobial prophylaxis was in placed in all participants. Ten cases of AML patients (4 male and 6 female) were included with a median age of 39 years (range: 19-49) and all of patients developed
febrile neutropenia. Firmicutes dominated during the period of neutropenic
fever, subsequently declining after bone marrow recovery a pattern in contrast to that shown by Bacteroidetes and Proteobacteria. Enterococcus was more abundant in the
febrile neutropenia period compared to pretreatment (mean difference +20.2; p < 0.0001) while Escherichia notably declined during the same period (mean difference -11.2; p = 0.0064). At the operational taxonomic unit (OTU) level, there was a significantly higher level of overall richness in the pretreatment period than in the febrile neutropenic episode (mean OTU of 203.1 vs. 131.7; p = 0.012). Both of the diversity indexes of Shannon and Simpson showed a significant decrease during the febrile neutropenic period. Adult AML patients with a first episode of
febrile neutropenia after initial intensive
chemotherapy demonstrated a significant decrease in gut microbiota diversity and the level of diversity remained constant despite recovery of bone marrow.