P1527: assessment of risk factors and antimicrobial therapy for carbapenem-resistant pseudomonas aeruginosa bloodstream infections in hematological patients

Topic: 22. Stem cell transplantation - Clinical Background: Infections caused by carbapenem-resistant Pseudomonas aeruginosa (CRPA) have been linked to increased mortality rates, particularly in patients with hematologic malignancies and those who received allogenic-hematopoietic stem cell transplantation. Aims: This retrospective study aimed to investigate clinical outcomes of CRPA bacteremia, identify associated risk factors and compare effectiveness of traditional and novel antibiotic regimen. Methods: This single-center retrospective study included patients with hematological diseases who were diagnosed with CRPA bacteremia between January 2014 and August 2022. The primary outcome was 30-day all-cause mortality, while secondary outcomes measured 7-day and 30-day clinical cure rates. Multivariable cox regression analysis was performed to identify risk factors associated with 30-day mortality. Results: A total of 100 patients diagnosed with CRPA bacteremia were included, of whom 29 had received allogenic-hematopoietic stem cell transplantation. Among the patients, 24 were treated with ceftazidime-avibactam (CAZ-AVI)-based therapy and 76 with traditional antibiotics. The study reported a 30-day mortality rate of 21.0%. Multivariable cox regression analysis identified neutropenia ≥7 days after BSI (P=0.030, HR: 4.068, 95%CI: 1.146~14.434), higher Pitt bacteremia score (P<0.001, HR:1.824, 95%CI: 1.322~2.517), higher Charlson comorbidity index (P=0.01, HR: 1.613, 95%CI: 1.124~2.315) and bacteremia due to multidrug-resistant Pseudomonas aeruginosa (MDR-PA) (P=0.024, HR:3.086, 95%CI: 1.163~8.197) as independent risk factors for 30-day mortality. After adjusting for confounders, an additional multivariable cox regression analysis revealed that definitive regimens containing CAZ-AVI were associated with lower mortality in CRPA bacteremia (P=0.016, HR: 0.150, 95%CI: 0.032~0.702) and MDR-PA bacteremia (P=0.019, HR: 0.119, 95%CI: 0.020~0.709). Summary/Conclusion: Among patients with hematological diseases and CRPA bacteremia, 30-day mortality rate was 21.0% (21/100). Neutropenia ≥7 days after BSI, higher Pitt bacteremia score, higher Charlson comorbidity index and bacteremia due to MDR-PA significantly increased 30-day mortality. CAZ-AVI-based regimens were found to be effective alternatives for the treatment of bacteremia caused by CRPA or MDR-PA.Keywords: Hematological malignancy, Infection, Stem cell transplant