According to this review colistin and tigecycline are the only reliable options against MBLs, a category of carbapenemase.
Here is a helpful review of resistance patterns, focusing on the European experience. Again colistin and tigecycline are discussed as the only alternatives for the most resistant isolates.
A discussion of the role of tigecycline.
Tigecycline for carbapenem resistant Acinetobacter.
Review of multidrug resistant gram negative infections in North America. Again, tigecycline and polymyxins are mentioned as the most viable alternatives.
Previous related posts here, here, here, here and here.
Note this quote from a review:
At New York Hospital Queens, KPC-producing Klebsiella have become endemic. Thus, neutropenic patients with serious hospital-acquired infection receive a five-drug regimen to treat a wide variety of potential multiresistant pathogens. This consists of polymyxin B, vancomycin, rifampin, tigecycline, and a carbapenem.