Comparative analysis of treatment outcomes and risk factors associated with different combination antimicrobial regimens in patients with multidrug-resistant Acinetobacter baumannii pneumonia.

BACKGROUND: Multidrug-resistant Acinetobacter baumannii (MDRAB) pneumonia is a major cause of mortality in hospital-acquired infections due to extensive drug resistance and limited therapeutic options. Optimizing treatment and identifying mortality-related factors are urgently needed.

OBJECTIVE: To compare the efficacy of different antibacterial regimens in MDRAB pneumonia and determine independent risk factors for 28-day all-cause mortality.

METHODS: This single-center retrospective cohort study included 142 MDRAB pneumonia patients from February 2022 to February 2025. Patients were divided into three groups: Group A, sulbactam-containing combinations (n = 63); Group B, polymyxins + tigecycline (n = 45); Group C, other regimens (n = 34). Outcomes included bacterial resistance patterns, 28-day mortality, dynamic PCT and CRP levels, APACHE II and SOFA scores, and lymphocyte subsets. Multivariate logistic regression identified mortality predictors.

RESULTS: Group A showed the lowest resistance to cefoperazone/sulbactam (30.16%) and the highest sensitivity (71.43%, both P< 0.05). Group B had the highest tigecycline resistance (31.11%). The 28-day mortality rates were 39.68% (A), 60.00% (B), and 64.71% (C) (P = 0.028). Independent mortality predictors were APACHE II, SOFA, and CD4+/CD8+ ratio (all P< 0.01). On day 7, Group A had the lowest PCT, while Group C showed the smallest declines in PCT and CRP. Group A exhibited the highest CD4+/CD8+ ratio.

CONCLUSION: Sulbactam-based combination therapy was associated with improved pathogen clearance and survival in this retrospective cohort. Mortality is closely linked to initial disease severity and early organ dysfunction. Dynamic changes in PCT and CD4+/CD8+ ratio have significant prognostic value.