Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt Rapid and visual detection of Salmonella in meat using invasin A (invA) gene- based loop-mediated isothermal amplification assay G. Bhuvana Priya a , Ravi Kant Agrawal b,* , A. Arun Prince Milton c , Madhu Mishra a , S.K. Mendiratta b , Ashish Luke b , Sofia Inbaraj a , Bhoj Raj Singh d , Deepak Kumar e , Gandham Ravi Kumar f , Swaraj Rajkhowa g a Division of Bacteriology & Mycology, ICAR-Indian Veterinary Research Institute, Izatnagar, 243122, Bareilly, Uttar Pradesh, India b Division of Livestock Products Technology, ICAR-Indian Veterinary Research Institute, Izatnagar, 243122, Bareilly, Uttar Pradesh, India c Division of Animal Health, ICAR- Research Complex for North Eastern Hill Region, Umiam, Meghalaya, India d Division of Veterinary Epidemiology, ICAR-Indian Veterinary Research Institute, Izatnagar, 243122, Bareilly, Uttar Pradesh, India e Division of Veterinary Biotechnology, ICAR-Indian Veterinary Research Institute, Izatnagar, 243122, Bareilly, Uttar Pradesh, India f National Institute of Animal Biotechnology, Hyderabad, Telangana, India g ICAR NRC on Pig, RANI, Guwahati, Assam, India ARTICLE INFO Keywords: Salmonella Food safety Foodborne pathogens Meat LAMP Rapid detection Enrichment Isothermal amplification ABSTRACT Salmonella, recognized as one of the most important foodborne bacteria has worldwide health and socio- economic impact. To prevent the occurrence of outbreaks and recall of food, a simple, rapid and robust detection test is needed. In the present study, a loop-mediated isothermal amplification (LAMP) assay was developed for rapid, sensitive and visual detection of Salmonella spp. and validated in meat using chevon as a model. The specificity of the developed LAMP was ascertained by using Salmonella and non-Salmonella strains. The devel- oped LAMP assay was 10 fold more sensitive than conventional PCR with the analytical sensitivity of 5 fg and 50 fg of DNA, respectively. In chevon samples artificially contaminated with S. Typhimurium, the LOD of LAMP was log 10 8.50 CFU/g, without enrichment, whereas, after short enrichment of meat for 6 h and 12 h, the sensitivity significantly improved with the detection limit of log 10 2.50 CFU/g and log 10 1.50 CFU/g, respec- tively. The current study demonstrates that the developed LAMP assay is a simple, sensitive and specific method to identify Salmonella which may be utilized in future for rapid detection of Salmonella in meat. The present study also highlights the importance of enrichment for sensitive detection of Salmonella from meat samples. 1. Introduction Foodborne non-typhoidal salmonellosis remains an important eco- nomic and public health burden for both developing and developed countries (Vinayaka et al., 2018). It causes bacterial gastroenteritis and is responsible for approximately 30% of foodborne outbreaks in the United States (Crump & Mintz, 2010) and 23% in European Union (EFSA, 2015). Globally, non-typhoidal Salmonella is accountable for 153 million cases (approx) of gastroenteritis and 57,000 deaths each year (Hunter & Francois Watkins, 2019). In India, the exact burden of foodborne diseases is not known. Majority of foodborne disease out- breaks go unreported, unrecognized or un-investigated and may only be noticed after major health or economic damage has occurred. Foods of animal origin are one of the most common sources of Salmonella in- fection (Leach et al., 1999). Contaminated food products such as eggs, poultry, chevon, pork and beef contribute to 75% of human Salmonella cases (Hoelzer, Switt, & Wiedmann, 2011; IFSAC, 2015, p. 2015; Pui et al., 2011). While prevalence data on Salmonella in animal origin foods in India are patchy, several reports are available in the public domain indicating the public health importance of the organism (Sharma et al., 2019; Waghamare et al., 2017; Naik, Shakya, Patyal, Gade, & Bhoomika, 2015; Kaushik, Anjay, Kumari, Bharti, & Dayal, 2014; Shekhar, Upadhyay, & Singh, 2013). Foodborne pathogens are regularly present in foods in low numbers which are usually masked by background micro-flora making their identification difficult (Kawasaki et al., 2010). Conventional detection methods for Salmonella spp. include pre- and selective enrichment, plating on selective media and biochemical testing which are highly specific and considered as the gold standard but these methods are time-consuming (require 7–10 days) and technically demanding https://doi.org/10.1016/j.lwt.2020.109262 Received 29 November 2019; Received in revised form 5 March 2020; Accepted 6 March 2020 * Corresponding author. E-mail address: ravikant7@rediffmail.com (R.K. Agrawal). LWT - Food Science and Technology 126 (2020) 109262 Available online 07 March 2020 0023-6438/ © 2020 Elsevier Ltd. All rights reserved. T