PurposeThe association between clinical and microbiological outcomes and high-dose tigecycline (TGC) was assessed in elderly (≥60 years old) patients with hospital-acquired and ventilator-associated pneumonia due to multidrug-resistant Acinetobacterbaumannii(A. baumannii). This study also assessed tigecycline combination with different antibiotics and its influence on the outcome.Patients and MethodsAn observational retrospective cohort study was conducted. Patients over 60 years old were treated with standard-dose (SD) TGC (100-mg intravenous TGC initially, followed by 50-mg doses administered intravenously twice daily) and high-dose (HD) TGC (200-mg intravenous TGC initially, followed by 100-mg doses administered intravenously twice daily) for a microbially confirmed infection. The outcome was 30-day crude mortality, co-administered antimicrobial agent and the microbial eradication percentage in both groups.ResultsA total of 48 multidrug-resistant A. baumannii respiratory patients were identified. Tigecycline was administered to 85% of ventilation-associated pneumonia (VAP) patients (28/33) in the SD group and 80% of VAP patients (12/15) in the HD group. Combined therapy was the major treatment option in both groups, accounting for 85% and 87%, respectively. Median treatment duration in both groups was 7.36 vs 8.6 days, respectively. Survival days were 13.61 vs 12.4 days (P=0.357), respectively. The 30-day crude mortality was 39.4% (13/33) for the SD group and 14% (2/15) for the HD group (P=0.098). The microbial eradication rate of respiratory specimens in the SD group was higher than that in the HD group (P=0.02). The variables associated with 30-day crude mortality were chronic obstructive pulmonary disease (hazard ratio [HR] 11.63, 95% CI 1.094–123.058; P=0.042), tigecycline treatment duration (HR 0.690, 95% CI 0.515–0.926; P=0.013), and surgery before infection (HR 79.276, 95% CI 6.983–899.979; P=0.000). High-dose tigecycline was not associated with 30-day crude mortality (adjusted HR 0.329, 95% CI 0.074–1.460; P=0.145). Combined antibiotics was also not different between the two groups.ConclusionsHigh-dose tigecycline was not associated with 30-day crude mortality in elderly patients with pneumonia due to multidrug-resistant A. baumannii, although the microbial eradication rate was high.