Rapid detection of the Klebsiella pneumoniae carbapenemase (KPC) gene by loop-mediated isothermal amplification (LAMP)

Klebsiella pneumoniae carbapenemases (KPC), which are associated with resistance to carbapenem, have recently spread worldwide and have become a global concern. It is necessary to detect KPC-producing organisms in clinical settings to be able to control the spread of this resistance. We have developed a loop-mediated isothermal amplification (LAMP) method for rapid detection of KPC producers. LAMP primer sets were designed to recognize the homologous regions of bla(KPC-2) to bla(KPC-17) and could amplify bla(KPC) rapidly. The specificity and sensitivity of the primers in the LAMP reactions for bla(KPC) detection were determined. This LAMP assay was able to specifically detect KPC producers at 68 degrees C, and no cross-eactivity was observed for other types of beta-lactamase (class A, B, C, or D) producers. The detection limit for this assay was found to be 10(0) CFU per tube, in 25 mm, which was 10-fold more sensitive than a PCR assay for bla(KPC) detection. Then, the sensitivity of the LAMP reactions for bla(KPC) detection in human specimens (sputum samples, urine samples, fecal samples and blood samples) was analyzed; it was observed that the LAMP assay had almost the same sensitivity in these samples as when using purified DNA. The LAMP assay is easy to perform and rapid. It may therefore be routinely applied for detection of KPC producers in the clinical laboratory. (C) 2014, Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.