Bloodstream Infections Due to Multidrug-Resistant Gram-Negative Organisms in Hematopoietic Stem Cell Transplant Recipients: A Multicenter Case-Control Study in a High-Prevalence Area.

Background: Over the last decade, an alarming increase in multidrug-resistant gram-negative (MDR-GN) pathogens has been recorded at hematopoietic stem cell transplant (HSCT) centers around the world. Infections caused by MDR-GN bacteria not only lead to treatment failure and longer hospital stays but also result in high morbidity and mortality rates.

Objective: To examine the incidence, risk factors, and outcomes of MDR-GN bacteremia among HSCT recipients in an area of high antimicrobial resistance.

Study design: Patients with bacteremia from 7 Greek HSCT centers were prospectively enrolled and followed up for 12 months. We compared patients with MDR-GN bacteremia to those with non-MDR-GN bacteremia, gram-positive (GP) bacteremia and matched controls without bacteremia in terms of demographics, clinical features, microbiology, and outcomes.

Results: In 523 HSCTs performed, we identified 142 episodes of bacteremia due to MDR-GN (38 patients), non-MDR-GN (37 patients), and GP pathogens (67 patients). The overall incidence of MDR-GN bacteremia was 1.4 per 1000 patient-days (95% confidence interval, 1.0-1.9), ranging from 0.0 to 2.9/1000 patient-days across participating centers (P = .01). When comparing patients with MDR-GN bacteremia to those with bacteremia caused by other organisms, in multivariate analysis, age and allogeneic HSCT were independent risk factors for MDR-GN bacteremia. The 12-month mortality rates were 34.5% in bacteremic patients, 60.5% for patients with MDR-GN, 32.4% with non-MDR-GN, and 20.9% with GP bacteremia (P < .001). MDR-GN bacteremia, relapse of the underlying disease, and GVHD were independent risk factors for death.

Conclusions: These findings highlight the importance of implementing rigorous infection control measures, in HSCT centers located in areas with high prevalence of antimicrobial resistance.