Changing Characteristics and In Vitro Susceptibility to Ceftazidime/Avibactam of Bloodstream Extensively Drug-Resistant Klebsiella pneumoniae from a Greek Intensive Care Unit

During 2014-2016, a total of 248 carbapenem-resistant Klebsiella pneumoniae (CARB-R Kp) were recovered in a Greek intensive care unit (ICU), the colistin resistance (COL-R) rates among CARB-R Kp from bloodstream infections (BSIs) were determined, and molecular characterization and the in vitro susceptibility of CARB-R+COL-R Kp to ceftazidime/avibactam were performed. The majority of CARB-R Kp from BSIs (n = 53) were OXA-48 (43.4%) and KPC (33.9%) producers, but no statistically significant differences were observed for the clinical characteristics of ICU patients affected by OXA-48 and other carbapenemase-producing K. pneumoniae. CARB-R+COL-R Kp (n = 28) represented 52.8% of 53 CARB-R Kp recovered from BSIs. The increase in the COL-R rates from 2014 to 2015 was mainly associated with the diffusion of extensively drug-resistant (XDR) OXA-48-co-producing CTX-M-15-like K. pneumoniae, assigned to multilocus-sequence typing ST101, possessing alterations in the mgrB loci. Ceftazidime/avibactam was active against all OXA-48 and KPC producers. Thus, the spread of XDR Kp possessing different types of carbapenemases further complicates the infection control strategies for the management of XDR Kp, whereas ceftazidime/avibactam may be a reasonable alternative to colistin for the treatment of XDR Kp in settings with low prevalence of metallo-beta lactamase-producing K. pneumoniae.