Pneumonia and Renal Replacement Therapy Are Risk Factors for Ceftazidime-Avibactam Treatment Failures and Resistance among Patients with Carbapenem-Resistant Enterobacteriaceae Infections

Abstract

Ceftazidime-avibactam was used to treat 77 patients with carbapenem-resistant <i>Enterobacteriaceae</i> (CRE) infections at our center. Thirty- and 90-day survival rates were 81% and 69%, respectively; these rates were higher than those predicted by SAPS II and SOFA scores at the onset of infection. Clinical success was achieved for 55% of patients but differed by the site of infection. Success rates were lowest for pneumonia (36%) and higher for bacteremia (75%) and urinary tract infections (88%). By multivariate analysis, pneumonia (<i>P</i> = 0.045) and receipt of renal replacement therapy (RRT) (<i>P</i> = 0.046) were associated with clinical failure. Microbiologic failures occurred in 32% of patients and occurred more commonly among patients infected with KPC-3-producing CRE than among those infected with KPC-2-producing CRE (<i>P</i> = 0.002). Pneumonia was an independent predictor of microbiologic failure (<i>P</i> = 0.007). Ceftazidime-avibactam resistance emerged in 10% of patients, including 14% of those infected with <i>Klebsiella pneumoniae</i> and 32% of those with microbiologic failure. RRT was an independent predictor of the development of resistance (<i>P</i> = 0.009). Resistance was identified exclusively among <i>K. pneumoniae</i> bacteria harboring variant KPC-3 enzymes. Upon phylogenetic analysis of whole-genome sequences, resistant isolates from 87.5% (7/8) of patients clustered within a previously defined sequence type 258 (ST258) clade II sublineage; resistant isolates from one patient clustered independently from other ST258 clade II isolates. In conclusion, our report offers new insights into the utility and limitations of ceftazidime-avibactam across CRE infection types. Immediate priorities are to identify ceftazidime-avibactam dosing and therapeutic regimens that improve on the poor outcomes among patients with pneumonia and those receiving RRT.