Prevalence and Antimicrobial Resistance of Listeria Species Isolated from Smoked and Salted Fish

Listeriosis is one of the most important food-borne diseases caused by Listeria species especially L. monocytogenes. The objective of this study was to determine the prevalence and antimicrobial resistance of Listeria species isolated from smoked and salted fish in Isfahan and Bandar anzali. From August 2009 to April 2011, a total of 120 samples of various smoked (n= 80) and salted Iranian fish (n= 40) were obtained from randomly selected retail stores in Isfahan and Bandaranzali cities and were evaluated for the presence of Listeria spp. using standard cultural and PCR methods. Then antibiogram tests were done for determination of antimicrobial resistance. 7 (8.8%) and 6 (15%) of smoked and salted fish samples were positive for Listeria spp. respectively. L. monocytogenes, L. innocua and L. seeligari were isolated from 2.5, 6.7 and 1.6% of fish samples. 9 of 13 Listeria isolates (69.2%) were resistant to one or more antimicrobial agents. Resistance to nalidixic acid (53.8%) and tetracycline (30.8%) were the most common finding. The results of this study indicate the potential risk of infection with Listeria in people consuming raw or under cooked smoked and salted fish. Also, the results obtained in this study indicate the need for an appropriate strategy of surveillance and epidemiological monitoring to control the development of resistance.