I think the Carba-NP assay is the most convenient one!
See also the following papers:
Vrioni G et al. Comparative Evaluation of a Prototype Chromogenic Medium (ChromID CARBA) for Detecting Carbapenemase-Producing Enterobacteriaceae in Surveillance Rectal Swabs. J. Clin. Microbiol. June 2012 vol. 50 no. 6 1841-184.
Huang TD et al. Comparative evaluation of two chromogenic tests for rapid detection of carbapenemase in Enterobacteriaceae and in Pseudomonas aeruginosa isolates. J Clin Microbiol. 2014 Aug;52(8):3060-3.
Dortet L et al. CarbAcineto NP test for rapid detection of carbapenemase-producing Acinetobacter spp. J Clin Microbiol. 2014 Jul;52(7):2359-64.
Nordmann P et al. Rapid detection of carbapenemase-producing Enterobacteriaceae. Emerg Infect Dis. 2012 Sep;18(9):1503-7.