Feasibility of Using Ceftazidime-Avibactam as a Therapeutic Option for Bloodstream Infections Caused by Multidrug-Resistant Enterobacterales and Pseudomonas aeruginosa Based on Its Susceptibility Profile.

Background In the era of increased antimicrobial resistance, there are limited therapeutic options available for the treatment of bacteremia caused by multidrug-resistant organisms (MDROs). This study aims to find out the feasibility of using ceftazidime/avibactam (CZA) as a therapeutic option for bloodstream infections caused by multidrug-resistant (MDR) Enterobacterales and based on its susceptibility profile. Materials and methods The isolates were routinely subjected to antimicrobial susceptibility testing (AST) by an automated AST system (VITEK-2). Those isolates found as MDR (resistant to at least one drug for ≥3 antimicrobial classes) were tested against CZA by Kirby-Bauer's disk diffusion (kb-DD) method. Results A total number of 293 MDR Enterobacterales and 31 MDR isolates were included. Of these, 87.3% of isolates were found as carbapenem-resistant (CR), whereas 12.7% of isolates were found as carbapenem susceptible. About 30.6% of MDROs were susceptible to CZA. Among carbapenem-resistant organisms (CROs), CR (33.5%) is most susceptible to CZA, compared to CR (0%)and CR(3.2%). Among the MDR isolates that were susceptible to CZA (30.6%), the majority had poor susceptibility against other β-lactam-β-lactamase inhibitor (BL-BLI) agents. Among all antimicrobial agents tested against CROs, colistin (96%) was found to have the best susceptibility profile. Conclusion It is observed that CZA is an acceptable therapeutic option for the treatment of bacteremia caused by MDROs, especially CROs. Therefore, it is important for the laboratories to perform the AST for CZA if the healthcare settings intend to use CZA for the management of such "difficult-to-treat" bloodstream infections.