بررسی لیستریا مونوسیتوژنس در ماهیان پرورشی تازه، دودی شده و بخهای مورد استفاده جهت نگهداری سرد ماهیان تازه در استانهای تهران و گیلان

Objective: To survey of Listeria monocytogenes in fresh and smoked fish and ice used in fish markets for retaining the freshness of the fish.
Design: Exploratory study.
Samples for analysis: fresh and smoked cultivated fish.
Procedure: Three hundreds of whole fresh and 40 smoked fish of various types were taken in fish markets and fish farms in Tehran and Gillan province of Iran. One hundred and twenty fish consisting of: rainbow trout (40 samples) as a cold water fish and silver carp (40 samples) and common carp (40 samples) as wann water fish and smoked silver carp (40 samples) came from the area of retail, another 180 fish included: rainbow trout (60 samples), silver carp and common carp (120 samples) were collected over 6 months from the area of delivery in fish trams. Also 120 samples of ice before addition to fish box and 120 ice samples after addition to fish boxes for retaining the freshness of the 120 fish were collected from the area of retail. The total of
340 fish and 240 ice samples were tested for prosence of Listeria
monocytogenes, using the modified Canadian version of U.S.
Food and Drug Administration (FDA) Listeria isolation method. As the bacterial intestinal flora of fish may reflect the condition of water, fecal samples of the each 180 fish were tested for presence of Listeria monocytogens.
Statistical analysis: Descriptive statistics.
Results: Incidence of Lisleria monocytogenes in the area of retail
were: 12.5% in rainbow trout, 10% in silver carp, 17.5% in common carp, 2.5% in smoked fish, 2.5% in samples of ice before addition to the fish boxes and 7.5% in samples of ice after addition to the fish boxes respectively. Also the incidence of Listeria monocytoges in the area of delivery in fish farms were: 11.6% in rainbow trout and 8.3% in silver carp and common carp respectively. Of 180 fecal samples tested, 7 samples contained Listeria monocytogenes.
Conclusion: According to the results, the hygienic procedures in fish marketing and consumption such as evisceration of the fish and sufficient cooking respectively, are recommendable. J. Fae. Vet. Med. Univ. Tehran. 57,4: 9-12, 2002.