To explore the efficacy and safety of non-carbapenem-containing (NCC) regimens and carbapenem-containing regimens (CC) regimens, along with the factors influencing the outcomes in critically ill patients with carbapenem-resistant Acinetobacter baumannii (CRAB) pneumonia. This study retrospectively enrolled critically ill patients with CRAB pneumonia who were treated with NCC and CC regimens in a teaching hospital. The primary efficacy outcome was the 28-day clinical efficacy rate, and the safety outcome was the incidence of nephrotoxicity. After the propensity score matching analysis removed the differences between the two groups, the differences in outcomes were statistically analyzed. Cox regression and logistic regression models were used to analyze the factors influencing the outcomes of critically ill patients with CRAB pneumonia. Data from 168 critically ill patients with CRAB pneumonia were eventually included in this study for analysis (NCC = 84, CC = 84). The 28-day clinical efficacy rate was significantly lower in the CC group compared to the NCC group (40.5% vs. 57.1%, P = 0.031), and the incidence of nephrotoxicity was not significantly different in the two groups (P >
0.05). Logistic analysis showed that the prescription of carbapenems was the risk factor of decreased clinical efficacy (aOR = 0.494, 95%CI = 0.262-0.932, P = 0.029) and reduced microbiological eradication (aOR = 0.397, 95%CI = 0.201-0.783, P = 0.008) in patients. CC regimen may not contribute to the 28-day clinical efficacy of CRAB pneumonia and further studies are necessary to elucidate the CC regimen when treating CRAB pneumonia in critically ill patients.