Effectiveness of Ceftazidime-Avibactam versus Colistin against Carbapenem-Resistant Enterobacteriaceae- A Retrospective Study

Background: This study compared the efficacy of ceftazidime-avibactam (CAZ-AVI) with colistin for treating carbapenem-resistant Enterobacteriaceae (CRE) infections. Materials & Methods: This retrospective study included ۱۲۰ patients with a confirmed CRE infection and information on causative bacteria and their susceptibility pattern. Patients were divided into two groups: those receiving CAZ-AVI and/or aztreonam (n=۵۳) and those receiving colistin (n=۶۷) for at least seven days. The colistin group was further subdivided into those who switched to CAZ-AVI due to poor outcomes. Patient data, including demographics, clinical history, microbiological data, Charlson comorbidity index, and outcomes, were collected and analyzed. Mann-Whitney U, Chi-square, and Fisher’s exact tests were used to compare the groups. P< .۰۵ was considered statistically significant. Findings: The findings revealed comparable clinical characteristics, there were no major differences in mean duration of hospitalization, intensive care unit (ICU) admission, and Charlson scores between the two groups. The CAZ-AVI group required a significantly longer duration of antibiotic treatment (p= .۰۱۸) and more source control measures (p= .۰۰۹). Klebsiella pneumoniae was the predominant causative pathogen in both groups, with NDM and OXA۴۸ carbapenem resistance genes being the most common. Toxicity (p= .۰۰۱) and mortality (p= .۰۴۹) were significantly higher in the colistin group. Higher improvement was observed among the CAZ-AVI group and higher mortality among the colistin group (p= .۰۴۹). Conclusion: CAZ-AVI could serve as an alternative to colistin for treating CRE infections. Further research is necessary to confirm these findings and provide evidence-based guidelines for managing CRE infections in India.

Keywords:

Carbapenem-resistant Enterobacteriaceae , Ceftazidime , Colistin , Drug resistance , Microbial , Outcomes