Rapid ResaImipenem/Acinetobacter NP Test for Detection of Carbapenem Susceptibility/Resistance in Acinetobacter baumannii

The rapid ResaImipenem/Acinetobacter NP test was developed for the identification of carbapenem resistance among Acinetobacter baumannii isolates. The principle of this test is based on the reduction of resazurin (a viability colorant) by metabolically active bacterial cells, hence detecting bacterial growth, in the presence of a defined concentration of imipenem chosen to be slightly above that defining imipenem resistance (6 μg/ml). Bacterial growth is visually detected by a color change from blue (resazurin) to purple or pink (resorufin product). A total of 110 A. baumannii isolates, among which 61 were imipenem resistant, were used to evaluate test performance. The sensitivity and specificity of the test were found to be 100%, in comparison with broth microdilution taken as the reference standard method. The rapid ResaImipenem/Acinetobacter NP test is highly specific and sensitive and is easy to implement in routine microbiology laboratories, and results are obtained within 2 h 30 min. It does not require any specific equipment.