Clinical Outcomes in Carbapenem-Resistant Enterobacteriaceae Infections Treated With Ceftazidime-Avibactam: A Single-Center Observational Study.

Introduction Among the several newer beta lactam+beta lactase inhibitors (BL/BLI), ceftazidime-avibactam is the only drug showing activity against OXA-48-like producers. Hence, it is being increasingly used in India to treat infections caused by carbapenem-resistant Enterobacteriaceae (CRE), especially as a colistin-sparing agent. We have used ceftazidime-avibactam in patients suspected and confirmed to have CRE infections in our center, and present a retrospective analysis of our experience. Methods We conducted a single-center, retrospective study involving all patients who were treated with ceftazidime-avibactam for suspected and proven CRE infections during a one-year period at our 500-bedded hospital. Our primary objective for this study was taken as all-cause mortality. The secondary objectives were to determine the clinical cure, defined as the end of the treatment regimen with a resolution of primary infection and resistance to ceftazidime-avibactam in patients who underwent the Epsilometer test (E-test). Results  A total of 103 patients who received ceftazidime-avibactam were identified. The all-cause mortality was 27% while a clinical cure was achieved in 73%. Fifty-two patients received empirical therapy and 51 patients received ceftazidime-avibactam for confirmed CRE infection. Forty-eight patients had an E-test done, out of which 79% of patients had CREs sensitive to ceftazidime-avibactam, and 21% of patients had ceftazidime-avibactam resistant CREs. A higher Sequential Organ Failure Assessment (SOFA) score, Charlson comorbidity index (CCI) score, intensive care unit (ICU) admission, inotrope requirement, and lower days of therapy (DOT) with ceftazidime-avibactam were found to be associated with increased mortality. Conclusion Colistin has been considered to be the last-line agent in CRE infections, but there are concerns about its adverse effects and the emergence of resistance. Given our relatively low mortality of 27% in CRE infections treated with ceftazidime-avibactam, coupled with the high susceptibility of the tested isolates, there may be a role for the empirical use of this drug in infections caused by CRE, especially in a setting where colistin may not be ideal.