Comparison of a novel, rapid chromogenic biochemical assay, the Carba NP test, with the modified Hodge test for detection of carbapenemase-producing Gram-negative bacilli.

We compared carbapenemase detection among 271 Gram-negative bacilli (of which 131 were carbapenemase producers) using a novel chromogenic rapid test--the Carba NP test (CNP)--and the modified Hodge test (MHT). Sensitivities were comparable (CNP, 100%, versus MHT, 98%; P = 0.08), but CNP was more specific (100% versus 80%; P < 0.0001) and faster.