We assessed the ability of three commercial systems to infer carbapenem 
resistance mechanisms in 39 carbapenemase-producing and 16 other 
carbapenem-resistant Enterobacteriaceae. The sensitivity/specificity values for 
"flagging" a likely carbapenemase were 100%/0% (BD Phoenix), 82 to 85%/6 to 19% 
(MicroScan), and 74%/38% (Vitek 2), respectively. OXA-48 producers were poorly 
detected, but all systems reliably detected isolates with KPC and most with 
metallo-carbapenemases.