A biochemical test (Carba NP test II) was developed to identify carbapenemase production in Enterobacteriaceae and Pseudomonas spp. and to discriminate between the different types of carbapenemases (classes A, B, and D). It is based on the detection of the acidification resulting from imipenem hydrolysis, coupled with tazobactam and EDTA as inhibitors. This is an easy and reliable technique (100% sensitivity and specificity) for detection of not only carbapenemase activity but also carbapenemase types in Enterobacteriaceae and Pseudomonas aeruginosa.