Direct detection of carbapenemase-associated proteins of Acinetobacter baumannii using nanodiamonds coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Detonation nanodiamonds (DNDs) are used for concentration and extraction of A. baumannii carbapenemase-associated proteins, i.e. ADC family protein, prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF-MS) analysis. Using ADC family protein as a biomarker (m/z ~ 40,279) for carbapenem susceptibility test of A. baumannii, the sensitivity and the specificity could reach 96% and 73% as compared to traditional imipenem susceptibility testing. However, the sensitivity and specificity of this method could reach 100% as compared to polymerase chain reaction (PCR) result. Our approach could directly detect the carbapenemase-associated proteins of A. baumannii within 90 min and does not require addition of carbapenemase substrate which is required in the MHT or other mass spectrometric methods and could be efficiently used in the detection of other carbapenemase-producing bacteria.292