Evaluation of loop-mediated isothermal amplification assays for rapid detection of blaKPC producing Serratia spp. in clinical specimens: A prospective diagnostic accuracy study

The prevalence of carbapenem-resistant Serratia spp. is increasing owing to the propagation of β lactamase Klebsiella pneumoniae carbapenemase (blaKPC) and it has become one of the major global health concerns. As effective therapies for such resistant pathogens are limited, there is a great need for the rapid and sensitive characterization of the pathogen. In the present study, a loop-mediated isothermal amplification (LAMP) method for the rapid detection of Serratia spp. with blaKPC in pure cultures and clinical specimens was developed. A calcein indicator and real-time turbidity recording system were used to assess the LAMP reaction. The LAMP assay was compared with conventional PCR and real-time PCR kits for the target pathogen. The desired amplification was achieved using selected primers and detection was possible using both the calcein indicator method and the real-time turbity recording system at 65˚C for 60 min. The sensitivity of the detection system for blaKPC-producing Serratia spp. reached a detection limit of 3.92 pg/µl DNA, which was 10 times more sensitive than conventional PCR. Specificity testing indicated that the primers were highly specific. Compared with conventional culture methods and real-time PCR, the LAMP assay was more sensitive, easier for laboratory staff to master and less influenced by the clinical specimen matrix. In conclusion, a LAMP assay for blaKPC-producing Serratia spp. that permitted rapid, sensitive and economical detection for this pathogen was successfully developed. Comparisons with alternative methods indicated that the LAMP assay was more feasible in a clinical setting.