Pervasiveness of Listeria monocytogenes in Milk and Dairy Products

Abstract

The study was carried out in milk and dairy products from Tiruchirappalli city, Tamil Nadu, India, to determine the incidence of Listeria monocytogenes. A total of 415 milk and dairy products were studied and L. monocytogenes were isolated from 219 (52.7%) samples. Among the positive samples, the raw milk and flavored milk were 100% contaminated by L. monocytogenes followed by branded milk (65.9%), cheese (62.5%), ice-cream (49.2%), milk powder (26.6%), milk sweets (20%), ghee and paneer (13.3%) and yoghurt (6.6%). Conversely, curd and butter were free from L. monocytogenes. In this study, the 23 isolates were identified through biochemical test, among the 23 isolates only 14 isolates were further confirmed by the detection of phosphatidylinositol phospholipase C gene (plcA) of L. monocytogenes through polymerase chain reaction. From the results concluded the milk and dairy products were more vulnerable for L. monocytogenes in Tiruchirappalli city would create awareness among people especially elderly people and children about the pathogen.