Intestinal Domination and the Risk of Bacteremia in Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

Infectious Disease Service, Department of Medicine.
Clinical Infectious Diseases (Impact Factor: 8.89). 06/2012; 55(7):905-14. DOI: 10.1093/cid/cis580
Source: PubMed


Bacteremia is a frequent complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). It is unclear whether changes in the intestinal microbiota during allo-HSCT contribute to the development of bacteremia. We examined the microbiota of patients undergoing allo-HSCT, and correlated microbial shifts with the risk of bacteremia.

Fecal specimens were collected longitudinally from 94 patients undergoing allo-HSCT, from before transplant until 35 days after transplant. The intestinal microbiota was characterized by 454 pyrosequencing of the V1-V3 region of bacterial 16S ribosomal RNA genes. Microbial diversity was estimated by grouping sequences into operational taxonomic units and calculating the Shannon diversity index. Phylogenetic classification was obtained using the Ribosomal Database Project classifier. Associations of the microbiota with clinical predictors and outcomes were evaluated.

During allo-HSCT, patients developed reduced diversity, with marked shifts in bacterial populations inhabiting the gut. Intestinal domination, defined as occupation of at least 30% of the microbiota by a single predominating bacterial taxon, occurred frequently. Commonly encountered dominating organisms included Enterococcus, Streptococcus, and various Proteobacteria. Enterococcal domination was increased 3-fold by metronidazole administration, whereas domination by Proteobacteria was reduced 10-fold by fluoroquinolone administration. As a predictor of outcomes, enterococcal domination increased the risk of Vancomycin-resistant Enterococcus bacteremia 9-fold, and proteobacterial domination increased the risk of gram-negative rod bacteremia 5-fold.

During allo-HSCT, the diversity and stability of the intestinal flora are disrupted, resulting in domination by bacteria associated with subsequent bacteremia. Assessment of fecal microbiota identifies patients at highest risk for bloodstream infection during allo-HCST.

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Available from: Lauren Lipuma, Sep 30, 2015
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    • "La perte de l'effet barrière conduit à l'augmentation des densités intestinales en bactéries normalement maintenues à basses concentrations, comme les entérocoques résistants à la vancomycine ou les entérobactéries, notamment suite à la prise d'antibiotiques actifs contre les bactéries anaérobies comme la clindamycine [20] [21]. Cette augmentation de la concentration des bactéries résistantes aux antibiotiques conduit à un risque plus élevé de diffusion dans l'environnement [21], de translocation digestive [22] ou d'infections urinaires [23] à ces bactéries. "
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    • "In the present study, duration of therapy with specific antibiotics was considered, unlike many earlier studies [12,13,16,17,19-22,24,27,28,30]. Exposure to anti-anaerobic antibiotics has been linked to VRE gastrointestinal tract colonisation [45] and bacteraemia [10,46]; however, the VRE genotype was either vanA VRE [10,46] or not determined [45]. In our study, an increase in duration of therapy with metronidazole (an anti-anaerobic antibiotic) was linked to VRE bacteraemia. "
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