Efficacy of Ceftazidime-Avibactam on the Carbapenem Resistant Strains of Enterobacteriaceae and Pseudomonas Aeruginosa - a Retrospective Study

Abstract

Background: Carbapenem-resistant Enterobacterales (CRE) and Pseudomonas aeruginosa (CRPA) are a big challenge in clinical practice because of restricted choices in treatment. Ceftazidime-avibactam (CZA) is considered a possible alternative, but its effectiveness depends on the mechanism of resistance. The susceptibility of carbapenem-resistant isolates to CZA is assessed in this study in a tertiary care hospital.
Methods: This was a retrospective observational study done between October 2023 and March 2024 in a tertiary care facility at Jamshedpur, India. Data were retrieved from the microbiology laboratory with emphasis on culture and antimicrobial resistance patterns of carbapenem-resistant Enterobacterales and P. aeruginosa. Antimicrobial susceptibility testing (AST) was done by Vitek2 compact system, and susceptibility to CZA was determined following CLSI guidelines (2023-2024).
Results: Out of 107 carbapenem-resistant isolates, Klebsiella pneumoniae (n=69, 63.89%) was the most common, followed by Escherichia coli (n=17, 15.74%) and P. aeruginosa (n=21, 19.44%). In total, 22 isolates (20.56%) were sensitive to CZA, with Klebsiella pneumoniae having the highest susceptibility (30.43%) and E. coli having minimal susceptibility (5.88%). All P. aeruginosa isolates were resistant to CZA.
Conclusion: CZA is moderately effective against CRE, especially Klebsiella pneumoniae, but not against CRPA. The results emphasize the importance of continued surveillance, antimicrobial stewardship, and novel treatment approaches against carbapenem-resistant infections. Research into combination therapies and new agents is essential to combat emerging resistance