INCIDENCE OF LISTERIA MONOCYfOGENES IN FROZEN AND REFRIGERATED FOODS

Abstract

Seven hundred and eighty five (785) samples comprising of frozen ( 185) and refrigerated (600) foods were randomly collected from Rawalpindi, Islamabad, Jhelum, Lahore, Kotli, Mansehra, Murree and Attock. The samples included various groups of foods i.e. milk and milk products, meat, vegetables and sweets. Collected samples were cold enriched. Primary isolation was procured on Acridine-Nalidixic acid agar medium. Isolates were confirmed morphologically and biochemically . . Out of seven hundred and eighty five (785) samples) 15 were found positive for Listeria monocytoeenes. 1\vo isolates were recovered from frozen food samples with 'a positive percentage of 1.08, while 13 isolates were recovered from refrigerated food samples with a positive percentage of 2.1. Overall percentage was recorded to be 1.91. Among food groups, highest percentage of isolation was in case of milk/vegetables (2.5%) followed by cheese (2.00%), curd (1.49%) and meat (1.36%). All the sweet:, samples we~~ found to be negative.'