Vancomycin-Resistant Enterococcus Found in Nearly One in Five Blood Cancer Patients Worldwide

A sweeping new systematic review and meta-analysis has quantified, for the first time on a global scale, how deeply vancomycin-resistant enterococci, or VRE, have taken hold among one of medicine’s most vulnerable patient populations: people with haematological malignancies. The study, published in Frontiers in Public Health, pooled data from 120 observational studies and found that nearly one in five of these patients—18.4 percent—carries or is infected with enterococci that no longer respond to vancomycin, one of the last-line antibiotics that clinicians rely on when safer drugs fail.

The research team, working under PRISMA 2020 reporting guidelines, searched PubMed, Scopus and Google Scholar for studies published up to March 2026, including only observational studies that reported the prevalence of VRE among patients with blood cancers and related conditions. Study quality was evaluated with the Joanna Briggs Institute checklist, and the pooled estimate was generated using a random-effects meta-analysis of logit-transformed proportions, a statistical approach well suited to prevalence data that range widely across studies. Calculations were performed in OpenMetaAnalyst and Comprehensive Meta-Analysis software, giving the authors two independent platforms to verify their results.

The headline figure of 18.4 percent, with a 95 percent confidence interval of 15.5 to 21.6 percent, conceals an extraordinary degree of variation between individual studies. The heterogeneity statistic I2 came in at 97.56 percent, with a p-value below 0.001, meaning that almost all of the observed variability between studies reflects real differences in settings, populations and methods rather than random statistical noise. In practical terms, the global average is a useful warning sign, but the true risk for any given patient depends heavily on where they are treated and what kind of haematological condition they have.

That geographic variation proved to be one of the most striking findings. South America recorded the highest pooled prevalence at 25.5 percent, followed by Australia at 22.8 percent, while other continents showed lower but still clinically significant levels. Meta-regression formally confirmed what the subgroup analysis suggested: continent was a significant contributor to heterogeneity, with a Cochran’s Q statistic of 11.68 and a p-value of 0.0395. By contrast, the laboratory detection method and the type of clinical sample tested were not significant moderators, suggesting that the differences are driven by genuine epidemiological factors—local antibiotic prescribing patterns, infection control infrastructure and regional strain ecology—rather than by how the bacteria were measured.

The patient-level breakdown is where the analysis becomes most alarming. Among haematopoietic stem cell transplantation recipients, the pooled prevalence of VRE reached 97.1 percent, a figure that approaches universality. Neutropenic patients, whose white blood cell defences have been stripped away by chemotherapy, showed a pooled prevalence of 91.2 percent, and patients with acute myeloid leukemia, the most aggressive of the common leukemias, came in at 68.3 percent. These subgroups represent patients whose immune systems are either deliberately ablated for transplantation or destroyed by disease and its treatment, leaving them almost defenceless against organisms that healthy people carry harmlessly in their gut.

Enterococci are intestinal commensals, organisms that normally live in the human gut without causing disease. The danger arises when the gut barrier is breached by intensive chemotherapy, mucositis from high-dose conditioning regimens, or prolonged neutropenia, allowing bacteria to enter the bloodstream. Vancomycin resistance, mediated primarily by the vanA and vanB gene clusters that alter the bacterial cell-wall target, means that first-line empirical therapy for febrile neutropenia may simply fail. For immunocompromised patients, a VRE bloodstream infection is not a routine resistant bug but a potentially fatal event with limited treatment options, often requiring linezolid or daptomycin, drugs with their own toxicity and resistance problems.

The authors were transparent about the limitations of their evidence base. Publication bias was detected through funnel plot asymmetry, with Egger’s regression test yielding a p-value of 0.0224 and Begg’s test a p-value of 0.0226, both statistically significant. This pattern suggests that smaller studies reporting higher prevalence figures were more likely to be published than those reporting low or null findings, which means the pooled estimate of 18.4 percent may be somewhat inflated relative to the true global figure. Sensitivity analyses were conducted to probe the robustness of the pooled result, and the systematic review was prospectively registered with the Open Science Framework, adding a layer of methodological accountability that is not always present in prevalence syntheses.

Why does this matter now? Antimicrobial resistance is frequently framed as a problem of intensive care units and long-term care facilities in high-income countries, but this analysis shows that the epicentre of risk sits squarely within haematology wards and transplant units worldwide. Patients with leukemia and lymphoma undergo repeated hospital admissions, receive broad-spectrum antibiotics for extended periods, and are exposed to the selective pressure that VRE needs to colonise and outcompete susceptible gut flora. The near-universal prevalence among transplant recipients suggests that in this population, VRE colonisation has become less an exception than the expected baseline in many centres.

The clinical implications follow directly from the numbers. Empirical antibiotic guidelines for febrile neutropenia may need to account for local VRE prevalence, with centres in high-prevalence regions such as South America and Australia potentially requiring earlier coverage of resistant enterococci. Surveillance cultures, gut decolonisation strategies and stringent contact precautions in transplant units are logical responses, though the review stops short of evaluating interventions. What the data do establish is a benchmark: any haematology service can now compare its own VRE rates against a rigorously pooled global estimate and its continental and patient-subgroup reference points.

For researchers, the 97.56 percent heterogeneity is both a caveat and a research agenda. The finding that continent, but not detection method or sample type, explains part of that variation points toward modifiable regional factors—antibiotic stewardship, infection control investment and healthcare-associated transmission networks—as the levers most likely to move prevalence. As the population of patients surviving blood cancers grows and more people undergo stem cell transplantation each year, the reservoir of immunocompromised hosts in whom VRE can flourish will only expand. This review provides the clearest quantitative picture yet of that reservoir, and it suggests that the window for containing vancomycin-resistant enterococci in haematology is narrowing.

Subject of Research: Global prevalence of vancomycin-resistant Enterococcus in patients with haematological malignancies

Article Title: Global prevalence of vancomycin-resistant Enterococcus in patients with haematological malignancies: a systematic review and meta-analysis

Article References: Aljebaly, F. S. M. (2026). Global prevalence of vancomycin-resistant Enterococcus in patients with haematological malignancies: a systematic review and meta-analysis. Frontiers in Public Health, 14, Article 1945305. https://doi.org/10.3389/fpubh.2026.1945305

Image Credits: AI Generated

DOI: 10.3389/fpubh.2026.1945305

Keywords: vancomycin-resistant Enterococcus, haematological malignancies, antimicrobial resistance, meta-analysis, systematic review, stem cell transplantation, neutropenia, acute myeloid leukemia, healthcare-associated infections, infection control, public health, Frontiers in Public Health