Assessment of urinary 3-indoxyl sulfate as a marker for gut microbiota diversity and abundance of Clostridiales

Abstract

<p id="d7225886e355"> <i>Objectives</i>: After allogeneic hematopoietic stem cell transplantation (allo-HCT), urinary levels of 3-indoxyl sulfate (3-IS) correlate with the relative abundance of bacteria from the class Clostridia (RAC), and antibiotic treatment is considered the major determinant of this outcome. A high RAC has been associated with favorable outcome after allo-HCT and protection from <i>Clostridium difficile</i> infection (CDI). We assessed correlations between alpha diversity, RAC and urinary 3-IS levels in a non-allo-HCT clinical cohort of antibiotic treated patients to further explore 3-IS as a biomarker of reduced diversity and predisposition to CDI. </p><p id="d7225886e363"> <i>Methods</i>: Fecal and urinary specimens were analyzed from 40 non-allo-HCT hospitalized patients before and 9 ± 2 days after initiation of intravenous antibiotic treatment. Fecal microbiota were analyzed by 16s RNA sequencing and urinary 3-IS was analyzed by liquid chromatography-tandem mass spectrometry. Receiver operating characteristic (ROC) analysis was performed to assess the predictive value of 3-IS. </p><p id="d7225886e368"> <i>Results</i>: At a RAC cutoff of &lt;30%, the binary logarithm of 3-IS (medium 3-IS: ≤2.5; high 3-IS: &gt;2.5) was predictive with an accuracy of 82% (negative predictive value: 87%, positive predictive value 67%). Accuracy was improved by combing antibiotic history with 3-IS levels (accuracy 89%, npv 88%, ppv 92%). </p><p id="d7225886e373"> <i>Conclusion</i>: In conjunction with patient antibiotic history, 3-IS is a candidate marker to predict RAC. </p>