Salmonelladetection with LAMP and qPCR and identification of serovars of interest by multiplex qPCR in poultry carcasses

Salmonellais present in the poultry production chain and is a major challenge in terms of food safety and animal health. The early Salmonelladetection is one of the main tools to control and prevent the transmission of this pathogen. Microbiological isolation and serotyping to identify and differentiate Salmonellaserovars are laborious processes, time-consuming, and expensive. Therefore, molecular diagnostic methods can be rapid and efficient alternatives to the detection of this pathogen. Thus, the aim herein was to standardize and evaluate the use of loop-mediated isothermal amplification (LAMP) in comparison with real-time PCR (qPCR) for detection of Salmonellaassociated with a multiplex qPCR for simultaneous identification and differentiation of S. Enteritidis, S. Typhimurium, S. Pullorum, and S. Gallinarum. The LAMP, qPCR, and multiplex qPCR assays were comparable in specificity. The three techniques were evaluated for specificity for 16 different serovars of Salmonellaand for 37 strains of the serovars of interest. The limit of detection and the efficiency of the LAMP, qPCR, and multiplex qPCR reactions were determined. The techniques were applied to 33 samples of chicken carcasses and compared to the results of conventional microbiology for validation. As results, LAMP was specific in the detection of different Salmonellaserovars but presented lower limit of detection ranging from 101to 104CFU/reaction. In comparison, qPCR could detect less cells (100to 102CFU/reaction), reaching equal specificity and better repeatability in the assays. The qPCR multiplexing for identification of the different serovars also showed good specificity, with the detection threshold between entre 101and 102CFU/reaction. The results obtained in the analyses on poultry carcasses suggested a correspondence between the results obtained in molecular methods and in conventional microbiology. Thus, the proposed assays are promising for the diagnosis of Salmonellain poultry carcasses, already proved to be faster and more efficient than conventional diagnostics techniques, being of great interest for poultry production, animal, and public health.