is a common human pathogen that causes several nosocomial chronic infections. Many methods have been reported to detect ; however， a simple， rapid， and visual method remains to be developed. Here， we developed a rapid， visual detection method employing a nanoparticle immunosensor (NPIS) with a sensitivity of 8 CFU mL. Two monoclonal antibodies (mAbs) recognizing different antigenic determinants on the surface of were screened by an indirect enzyme-linked immunosorbent assay (ELISA)， Western blotting， and mass spectrometry assay. The mAb 1E6 was conjugated to magnetic nanoparticles (MNPs) to generate the immuno-magnetic nanoparticles (IMNPs)， whereas the horseradish peroxidase (HRP)-mAb probe was synthesized by conjugating the mAb 2F1 with HRP. Thereafter， the NPIS was developed based on the IMNPs and the HRP-mAb probe， and the total assay time for the detection of was ～60 min. A rapid， sensitive method was developed for screening in clinical samples. The NPIS developed in this study can detect Klebsiella pneumoniae without the enrichment of bacteria and the extraction of the genome; therefore， it can be used as a primary screening method to compliment other methods in the detection of .