Use of Magnetic Nanoparticles for the Detection of Multidrug-Resistant Acinetobacter baumannii

Acinetobacter baumannii is the most important pathogen causing large-scale nosocomial infections and has a high ability to acquire drug resistant genes such as OXA. Because traditional antimicrobial susceptibility test is time-consuming, it is urgent to establish fast and convenient methods of polymerase chain reaction (PCR) and real-time PCR for screening of multi-drug resistant A. baumannii (MDR-Ab). The present employed magnetic nanoparticles to purify the DNA from A. baumannii. The DNA templates were then used for multiplex-PCR and real-time PCR amplification. The presence of A. baumannii OXA gene including blaOXA-23, blaOXA-24, blaOXA-51, blaOXA-58, and efflux pump genes such as adeB, adeJ, macB, emrA, emrB, abeS, abeM, craA was analyzed. The A. baumannii DNA could be extracted rapidly and with high quality by magnetic nanoparticles and was suitable for PCR detection. There was no significant difference between carbapenem-resistant and carbapenem-sensitive A. baumannii in terms of efflux pump genes. The blaOXA-24 and blaOXA-58 genes were not detected in any of the samples tested. In the carbapenem-resistant group, blaOXA-23 and blaOXA-51 genes were detected, and in the carbapenem-sensitive group, blaOXA-51 gene was present. These results indicate that magnetic nanoparticles provide a new fast method for A. baumannii DNA purification, which is suitable for rapid clinical diagnosis. The blaOXA-23 gene is a potential marker for carbapenem-resistant A. baumannii in our hospital. In conclusion, DNA template preparation by magnetic nanoparticles and detection of the blaOXA-23 gene by PCR provide a novel method for carbapenem-resistant A. baumannii screening.