Gut colonization with vancomicyn-resistant enterococci among patients with hematologic malignancies

Vancomycin-resistant enterococci (VRE) are well known agents that colonize the gastrointestinal tract of immunocompromised patients, especially those with hematologic malignancies. The aim of the current study was to determine the incidence of and risk factors for colonization with VRE among patients with hematologic malignancies.

For a nine-month period, all patients admitted to the Hematology ward at University Hospital in Pleven, Bulgaria who had hematologic malignancy and duration of hospitalization of more than 48 h were screened for colonization with VRE. The data collected from patients and their medical records during the entire hospital stay included: demographic characteristics, clinical information and information about all antimicrobials used. A longitudinal study was used to assesses the risk factors and statistical analysis was performed using SPSS version 27.0.

A total of 119 patients were enrolled in the study. Colonization with VRE was established in 18 of them. One patient carried two species, resulting in a total of 19 VRE: 12 Enterococcus gallinarum, 4 Enterococcus casseliflavus, 2 Enterococcus faecium and 1 Enterococcus faecalis. VanA phenotype, with high-level resistance of vancomycin (MIC ≥ 256 μg/ml) and teicoplanin (MIC = 96 μg/ml), was demonstrated by one E. faecium, which carried vanA. The other E. faecium and E. faecalis expressed low-level resistance to vancomycin (MICs: 8 μg/ml and 12 μg/ml), susceptibility to teicoplanin (MICs = 0.5 μg/ml) and vanB was detected. All E. gallinarum and E. casseliflavus showed low-level resistance to vancomycin and susceptibility to teicoplanin. E. gallinarum strains were positive for vanC1 and E. casseliflavus for vanC2. Only two patients were colonized with vanA or vanB enterococci and the rest 16 were positive for vanC. The univariate analysis revealed that patient's age (70-79 years; p = 0.025) and multiple myeloma (p = 0.001) are risk factors for VRE acquisition among the investigated patients. In addition, the multivariate analysis confirmed that patient's age (70-79 years) is an independent risk factor for VRE colonization.

Our results showed that 15.1% of patients with hematologic malignancies were colonized with VRE. There was a distinct prevalence of vanC enterococci. Among the analyzed risk factors, advanced age and multiple myeloma contributed to VRE acquisition.