Leonard Knegendorf (Hannover / DE), Claas Baier (Hannover / DE), Dirk Schlüter (Hannover / DE), Nicole Brüder (Hannover / DE), Florian H. Heidel (Hannover / DE), Michelle Eder (Hannover / DE), Ella Ebadi (Hannover / DE), Gernot Beutel (Hannover / DE)
Background
Infections, especially bloodstream infections (BSI), are a common complication in patients undergoing allogeneic stem cell transplantation (allo-SCT). Beyond the detection of infections, microbiological screening performed on patients with hematologic neoplasms frequently detects bacterial isolates that colonize patients.
Methods
We retrospectively identified all adult patients who underwent allo-SCT at Hannover Medical School (Germany) between 2015 and 2020. Microbiological data was extracted from the laboratory information system. Screening results (from for example stool samples/rectal swabs) were included from specimens collected up to 100 days prior to and 20 days after allo-SCT. The assessment of blood culture specimens was limited to a period of 10 days prior to and 20 days after allo-SCT.
Results
During the study period, 503 patients underwent allo-SCT, resulting in 516 cases. Among the collected specimens, blood cultures from 216 cases showed at least one positive result. Gram-negative bacteria (GNB) and enterococci were found in 104/216 (48.1%) of these cases (Figure 1A). In 57/216 (26.4%) of the cases the isolates in the blood were also found in intestinal screening specimens (stool/rectal swab), as determined by species comparison. All matching isolates were either GNB or enterococci (57/104; 54.8%).
Of the 516 transplantation cases, 6 had MRSA colonization, 173 had VRE, 7 had Carbapenem-resistant (CR) Enterobacterales or Acinetobacter sp. and 65 had ESBL-phenotype GNB in combination with fluroquinolone resistance (Figure 1B).
Discussion
In this analysis, we evaluated bacterial colonization and BSI of allo-SCT patients. Our findings reveal a high prevalence of VRE and a low occurrence of CR GNB. Both have important implications for IPC strategies, as these organisms can precipitate nosocomial infections. Furthermore, over half of the BSI cases with GNB and enterococci showed a species match with intestinal screening samples. In the context of oral decontamination strategies, the identification of ESBL-producing bacteria resistant to fluoroquinolones is particularly remarkable.