Multidrug resistant (MDR) gram-negative pathogens, especially Enterobacteriaceae, are emerging worldwide. The MDR pattern is relatively common with resistance appearing to all major classes of anti-gram-negative agents (e.g. B-lactams, fluoroquinolones, and aminoglycosides], and in some cases, resistance to all available drugs. This is particularly worrisome in view of the current dearth of new compounds active against MDR gram-negatives in the pipeline.