Ceftazidime/avibactam combined with colistin: a novel attempt to treat carbapenem- resistant gram-negative bacilli infection

Abstract

Background The rapid global emergence and spread of carbapenem-resistant gram-negative bacilli (CRO) is recognized as a major public health concern, and there are currently few effective treatments for CRO infection. The aim of this study was to investigate the clinical characteristics and outcomes of patients with CRO infections treated with ceftazidime/avibactam (CAZ/AVI) combined with colistin from October 2019 to February 2023 in China. Methods A total of 31 patients with CRO infections were retrospectively identified using the electronic medical record system of Zhejiang Provincial People's Hospital. Results Thirty-one patients were treated with CAZ/AVI combined with colistin. Respiratory tract infections (27/31, 87%) were most common. Pathogens included carbapenem-resistant Klebsiella pneumoniae (17/31, 54.8%), carbapenem-resistant Acinetobacter baumannii (9/31, 29.0%), and carbapenem-resistant Pseudomonas aeruginosa (5/31, 16.1%). The 30-day mortality rate was 29.0%, and the average lengths of hospital and ICU stay among all patients were 39.0 and 17.0 days, respectively. The average lengths of ICU stay among the survivors and non-survivors were 19.7 and 10.7 days, respectively (P = 0.023). In addition, the pathogen was cleared within 7 days in 20 patients (20/31, 64.5%). Among all patients, average levels of the inflammatory indicator CRP were significantly lower 7 (152.23 ± 68.42 mg/L vs 94.56 ± 56.86 mg/L, P = 0.002) and 14 (152.23 ± 68.42 mg/L vs 83.20 ± 55.87 mg/L, P = 0.005) days after combination therapy than levels 24 h before therapy. Similarly, CRP levels among the survivors were significantly lowered by treatment, with 145.61 ± 70.42 mg/L vs 94.82 ± 53.76 mg/L (P = 0.018) at 7 days and 145.61 ± 70.42 mg/L vs 86.16 ± 57.98 mg/L (P = 0.027) at 14. However, there were no significant differences in PCT or WBC levels among all patients or among survivors. Conclusions CAZ/AVI combined with colistin reduced the inflammatory response in patients with CRO infection, but more studies will be needed to determine whether the combination can increase the 7-day microbial clearance rate and reduce the 30-day mortality rate.