Volume Issue 1 DR-2095 [1-5] RESEARCH ARTICLE Asian Journal of Dairy and Food Research Application of MALDI-TOF Mass Spectrometry for the Assessment of Prevalence of Listeria monocytogenes in Raw Milk, Dairy Products and Freshwater Fishes Rahul Suryawanshi 1 , Ashok Bhosale 2 , Gopal Bharkad 3 , Onkar Shinde 1 , 10.18805/ajdfr.DR-2095 Aishwarya Jogdand 1 , Niraj Hatwar 1 , Hrishikesh Kamat 1 ABSTRACT Background: Foodborne infections like Listeriosis cover several disorders and are a worldwide public health emergency. Listeria monocytogenes has been isolated from various foodstuffs, including milk and fishes. MALDI-TOF mass spectrometry technique is known for its rapid and accurate identification of bacterial organisms. Methods: In the current research, a total of 360 samples comprising raw milk (130), milk products (125) and freshwater fishes (105) were screened for the detection of pathogenic Listeria species by using the USDA method. The recovered Listeria isolates were characterized using conventional set of biochemical analysis along with sugar fermentation tests and further confirmed by MALDI- TOF MS. The virulent nature of pathogenic Listeria isolates was also assessed by in vitro tests like hemolysis on blood agar, CAMP and PI-PLC assay. Result: In current study, on screening 360 animal origin food samples, three isolates were recovered from raw milk samples and identified as Listeria monocytogenes indicating an overall prevalence of Listeria monocytogenes to the tune of 0.83%. Excellent correlation was observed with identification of Listeria species using conventional phenotypic tests and advanced molecular tool Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) technique. The results depict dependability of advanced technique for rapid and reliable identification of Listeria species. Key words: CAMP, Listeria monocytogenes, MALDI-TOF MS, PI-PLC assay. INTRODUCTION Listeriosis is an important foodborne disease in humans because it is associated with the ingestion of contaminated food and water with pathogenic Listeria spp. (Low and Donachie, 1997). It leads to severe invasive illness in humans; the main signs are septicemia, abortion, stillbirth, perinatal infections, meningitis, gastroenteritis and meningoencephalitis, particularly in aged and immuno compromised individuals (Posfay-Barbe and Wald 2004). Pregnant women are more vulnerable to infection than non- pregnant women, which can result in abortion, stillbirth, or perinatal illnesses (Jackson et al., 2010). The incidence of listeriosis caused by this bacterium has skyrocketed in recent years. Most human listeriosis occurs when contamination levels of 102-106 CFUs/ml or/g of Listeria are present in food (Dawson et al ., 2006). Listeria monocytogenes has been isolated from various foodstuffs, including milk (Barbuddhe et al., 2002). Several incidences of foodborne listeriosis have been reported caused by consuming contaminated meat (Lunden et al ., 2003; Bhandare et al., 2007). Matrix-assisted laser desorption/ ionization-time of flight (MALDI-TOF) mass spectrometry (MS) is a single identification and source-tracking tool for L. monocytogenes (Jadhav et al., 2015). This technique examines the chemistry of major proteins, yielding profile spectra consisting of a series of peaks, a characteristic “fingerprint” mainly derived from ribosomal proteins and the fingerprinting has the potential for bacteria identification and subtyping (Barbuddhe et al., 2008). It has become the method of choice for bacterial species identification in clinical diagnostics due to its little hands-on and turnaround time, low costs and high accuracy (Angeletti and Ciccozzi, 2019; Rodrı ìguez-Saìnchez et al., 2019). The present study was 1 Department of Veterinary Public Health, College of Veterinary and Animal Sciences, Udgir-413 517, Latur, Maharashtra, India. 2 Department of Veterinary Microbiology, College of Veterinary and Animal Sciences, Udgir-413 517, Latur, Maharashtra, India. 3 Department of Veterinary Parasitology, College of Veterinary and Animal Sciences, Udgir-413 517, Latur, Maharashtra, India. Corresponding Author: Rahul Suryawanshi, Department of Veterinary Public Health, College of Veterinary and Animal Sciences, Udgir-413 517, Latur, Maharashtra, India. Email: rahulvph@gmail.com How to cite this article: Suryawanshi, R., Bhosale, A., Bharkad, G., Shinde, O., Jogdand, A., Hatwar, N. and Kamat, H. (2023). Application of MALDI-TOF Mass Spectrometry for the Assessment of Prevalence of Listeria monocytogenes in Raw Milk, Dairy Products and Freshwater Fishes. Asian Journal of Dairy and Food Research. doi:10.18805/ajdfr.DR-2095. Submitted: 18-03-2023 Accepted: 17-05-2023 Online: 02-06-2023