Evaluation of the relative effectiveness of various antibiotic regimens used to treat hospital-acquired pneumonia induced by drug-resistant Acinetobacter baumannii.

OBJECTIVE: This study aimed to compare the effectiveness of different antimicrobial regimens used in the treatment of hospital-acquired pneumonia caused by extensively drug-resistant Acinetobacter baumannii (XDRAb-HAP).

METHODS: A retrospective analysis was performed using clinical data from 376 patients diagnosed with XDRAb-HAP across four tertiary teaching hospitals in China between January 2017 and May 2022.

RESULTS: The overall 30-day treatment failure rate was 55.1 % (207/376). Multivariate logistic regression identified immunocompromised status, APACHE II score, septic shock, invasive mechanical ventilation, and delayed initiation of definitive therapy as independent predictors of 30-day treatment failure. After adjusting for potential confounders, tigecycline (TGC) monotherapy was associated with a significantly higher risk of 30-day treatment failure compared with polymyxin B (PMB) monotherapy (OR 8.910, 95 % CI 3.211-24.724, p < 0.001). A comparable risk was observed with the PMB plus TGC combination (OR 1.290, 95 % CI 0.619-2.689, p = 0.496). The addition of sulbactam (OR 0.636, 95 % CI 0.276-1.465, p = 0.288) or a carbapenem (OR 1.066, 95 % CI 0.496-2.290, p = 0.871) did not significantly influence the 30-day treatment outcome compared with regimens lacking these agents. Weighted propensity score analyses further supported these associations between treatment regimens and clinical outcomes.

CONCLUSION: In the current therapeutic landscape, lacking effective novel agents, PMB appears to be a reasonable first-line option for managing XDRAb-HAP. However, PMB-based combination therapies did not demonstrate improved clinical efficacy over PMB monotherapy.