| Congresso Brasileiro de Microbiologia 2023 | Resumo: 524-1 | ||||
Resumo:Acute lymphoblastic leukemia (ALL), the most prevalent hematological malignancy in children, leaves patients more susceptible to opportunistic infections due to intestinal dysbiosis during chemotherapy treatment, including potentially fatal bloodstream infections. Further complications arise due to the prophylactic or therapeutic use of antibiotics, which often exacerbates intestinal dysbiosis by disrupting the gut microbiota balance, facilitating the overgrowth and persistent colonization by opportunistic pathogens. Considering the impact of antibiotics on the intestinal microbiota, this study aimed to characterize the gut microbiota of children diagnosed with ALL before chemotherapy initiation. This is a preliminary study of an ongoing project which intends to characterize the gut microbiota of children with ALL before and during chemotherapy. After ALL diagnoses by the clinical staff, the entire stool volume was collected by spontaneous evacuation before chemotherapy initiation. DNA was extracted from the samples using ZymoBIOMICS™ DNA Miniprep D4300, with some modifications. The V3-V4 hypervariable region of the 16S rRNA amplicons was obtained using universal primers 357F/805R. Metagenomic libraries were built using the Illumina Nextera XT DNA Library Prep Kit, and the amplicons were sequenced on an Illumina NextSeq 1000 sequencer using a paired-end protocol. The raw data were trimmed using Trimmomatic version 0.39 and imported into the QIIME2 software. The good-quality sequences were grouped using the DADA2 algorithm. The USEARCH pipeline in QIIME2 and SILVA database release 138 were used for taxonomic classification. Beta diversity and taxonomic comparisons were performed using STAMP 2.1.3. Clinical and epidemiological data were obtained from the institutional medical records. In this study, nine patients were evaluated, five of whom were female. Their ages varied from 1 to 11 years (mean 6.1 years). During admission, three patients were using antibiotics (ATB), three patients were using non-antibiotic medications (non-ATB), and the other three patients did not use any medication. At the phylum level, patients with prior ATB administration showed lower proportions of Firmicutes and slightly higher proportions of Actinobacteria and Proteobacteria in their microbiota than the other groups. Although Actinobacteria benefit intestinal health, an increase in Proteobacteria is associated with intestinal dysbiosis. Approximately 30% of the gut microbiota in both groups comprised different proportions of Bifidobacterium, Faecalibacterium, and Blautia species. Enterococcus faecalis accounted for up to 14.6% of the microbiota in the ATB group. This result indicated probable colonization due to antibiotic use. All three groups shared 46 taxa. The ATB group had 11 exclusive taxa, including the genus Klebsiella, which is highly associated with bloodstream infections. In conclusion, antibiotic use may be implicated in the persistent colonization of opportunistic pathogens and antibiotic resistance. Although E. faecalis and Klebsiella spp. are commensal microorganisms, both may cause severe infections under suitable conditions, mainly in hospitalized patients. Therefore, once a patient is identified as at risk of infection at the ALL diagnosis, customized treatment to modify the gut microbiota composition could be applied to improve the prognosis during chemotherapy. Palavras-chave: Gut microbiome, high-throughput sequencing, intestinal dysbiosis, acute lymphoblastic leukemia Agência de fomento:Programa Nacional de Apoio à Atenção Oncológica (PRONON) | |||||