Vancomycin-resistance gene cluster, vanC, in the gut microbiome of acute leukemia patients undergoing intensive...

Area of Science:

• Microbiology
• Immunology
• Hematology

Background:

• Less common enterococcal species, Enterococcus gallinarum and E. casseliflavus, possess low-level vancomycin resistance via vanC genes.
• Previous research indicates peri-transplant gut colonization with these species correlates with reduced mortality post-allogeneic hematopoietic cell transplantation (HCT).
• Acute leukemia patients undergoing HCT often receive intensive chemotherapy, potentially leading to acquired vanC-positive enterococci.

Purpose of the Study:

• To investigate the prevalence of vanC-positive enterococci in acute leukemia patients undergoing intensive chemotherapy prior to HCT.
• To determine if these vanC-positive enterococci are acquired during chemotherapy and if they persist into the HCT period.

Main Methods:

• Quantitative PCR (qPCR) targeting vanC1 and vanC2/3 gene clusters was used.
• Stool samples were collected thrice-weekly from 20 acute leukemia patients undergoing intensive chemotherapy.
• 16S rRNA gene sequencing was employed for comparison with qPCR results.

Main Results:

• A significant proportion of patients (15% for vanC1, 35% for vanC2/3) had detectable vanC genes in at least one stool sample.
• qPCR results, when compared to 16S rRNA gene sequencing, suggest Enterococcus gallinarum may achieve high abundance.
• The findings indicate potential persistence of these bacteria into the HCT period.

Conclusions:

• VanC-positive enterococci, specifically Enterococcus gallinarum and E. casseliflavus, are detectable in acute leukemia patients during intensive chemotherapy.
• These findings support the hypothesis that vanC-positive enterococci may be acquired during chemotherapy and could potentially influence HCT outcomes.