Phenotypic, biochemical, and molecular techniques for detection of metallo-β-lactamase NDM in Acinetobacter baumannii.

Seven NDM-positive Acinetobacter baumannii isolates of worldwide origin were studied to evaluate the best technique for their identification. Detection of carbapenemase producers based on the measurement of carbapenemase activity by UV spectrophotometry (as for A. baumannii strains producing other types of carbapenemase), or by the modified Hodge test, failed. Inhibition activity using EDTA was a sensitive technique but lacked specificity compared to molecular techniques, which remain the gold standard.