Clinical Impact of Ceftazidime/avibactam on the Treatment of Suspected or Proven Infections in a Large Cohort of Patients with Haematological Malignancies: a Multicentre Observational Real-World Study.

Objectives: To evaluate clinical impact of ceftazidime/avibactam on treating infections due to MDR Gram-negative bacteria in patients with haematological malignancies (HMs). Methods: We conducted a retrospective, observational study at 17 Italian haematological wards that included patients with HMs receiving ceftazidime/avibactam for the treatment of suspected or proven infections. The primary endpoint was all-cause mortality 30 days after infection onset. Secondary endpoints included the development of in vitro ceftazidime/avibactam resistance, adverse reactions and infection relapse. Results: Of 198 patients enrolled, 66 had fever of unknown origin and 132 had microbiologically proven infections (MPIs). Enterobacterales were responsible for 98 MPIs, with KPC producers accounting for 75% of these, and carbapenem-resistant Pseudomonas aeruginosa caused 25% of MPIs. The overall 30-day mortality rate was 17.7%. Infection relapse occurred in four patients with MPI. Patients who died within 30 days of infection onset tended to have pre-existing cerebrovascular diseases, a Charlson Comorbidity Index > 4 and septic shock at infection onset and had received inadequate initial antibiotic therapy. Thirty-day mortality was independently associated with septic shock at infection onset and inappropriate initial antibiotic therapy. Conclusions: Our study provides further evidence about the effectiveness of ceftazidime/avibactam in treating infections in patients with HMs.