Fluoroquinolone-Free Prophylaxis and Impact on Bacterial Infections, Resistance, and Survival in Allo-HSCT: 5-year follow up of the BATMO protocol (Best Anti-microbical Therapy Trapianto di Midollo Osseo)
Daniele Avenoso, Mirko Farina, Simone Ferri, Lorenzo Masina, Liana Signorini, Silvia Lorenzotti, Evelyn Van Hauwermeiren, Biagio Francesco Canino, Silvia Corbellini, Francesca Caccuri, Gabriele Magliano, Enrico Morello, Vera Radici, Simona Bernardi, Federica Re, Alessandro Leoni, Arnaldo Caruso, Domenico Russo, Michele MalagolaAbstract
Background
Infectious complications and antimicrobial resistance (AMR) are leading causes of morbidity and non-relapse mortality (NRM) in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). The BATMO protocol, implemented in 2019, removed fluoroquinolone prophylaxis and introduced a personalized, stewardship-based antimicrobial approach.
Methods
We retrospectively analysed 323 allo-HSCT recipients transplanted between 2016 and 2023 at a single centre, comparing outcomes in patients before (n=115) and after (n=208) BATMO implementation. Primary endpoints included overall survival (OS), NRM, incidence and microbiology of bloodstream infections (BSIs), antimicrobial resistance trends, and carbapenem use. Kaplan-Meier and cumulative incidence methods were employed.
Results
Despite a significant increase in 30-day Gram-negative BSI incidence post-BATMO (24% vs 15%, p=0.03), OS and NRM were similar between the two cohorts. Notably, the post-BATMO cohort included a substantially higher proportion of high-risk transplants, with a marked increase in haploidentical procedures and broader use of post-transplant cyclophosphamide. Interestingly, fluoroquinolone-resistant E. coli strains declined from 100% to 46% (p=0.003), and overall Gram-negative resistance dropped from 75% to 36% (p=0.006). Use of carbapenems remained unchanged (43% vs 53%, p=0.1).
Conclusions
The BATMO protocol demonstrates that withdrawal of fluoroquinolone prophylaxis and implementation of a targeted antimicrobial strategy can reduce resistance without compromising transplant outcomes. These findings support the long-term safety and efficacy of stewardship-based approaches in allo-HSCT.