Here is a review on the topic. These regimens have been our go-to for a while now and are effective although the crude mortality for these infections remains high, in the 30+% range. Newer antibiotics either approved or in the pipeline have brightened the outlook. From the article:
A few emerging treatment options for CPKP infections appear promising. The most prominent new agent is ceftazidime–avibactam, a cephalosporin combined with a novel β-lactamase inhibitor approved by the US Food and Drug Administration (FDA) in February 2015 . Ceftazidime–avibactam has shown potent in vitro activity against CRE isolates [61–63]. and there have also been reports that ceftazidime–avibactam is effective for CPKP infections after other combination regimens have failed [19, 64, 65]. Other β-lactam/β-lactamase inhibitor combinations are also being investigated including ceftolozane–tazobactam and aztreonam–avibactam [12, 66]. Plazomicin, a novel aminoglycoside that has shown in vitro activity against CRE, is currently undergoing a Phase 3 clinical trial (NCT01970371) as part of a combination therapy . Another agent showing potential is eravacycline, a tetracycline derivative, which has shown in vitro efficacy against CRE as well as for complicated intra-abdominal infections and complicated urinary tract infections in clinical trials [68, 69].