Isolation and characterization of Listeria monocytogenes from tropical seafood of Kerala, India
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Listeria monocytogenes, which is an intracellular pathogen, causes various illnesses in human as well as in animals. The pathogenicity of this organism depends upon the presence of different virulence genes. A total of 324 tropical seafood and fishery environmental samples were screened for L. monocytogenes. The incidence of the human pathogenic species L. monocytogenes was 1.2 % of the samples. Listeria spp. was detected in 32.3, 27.1, and 5 % of fresh, frozen, and dry fish samples, respectively. Listeria innocua was found to be the most prevalent species of Listeria in the tropical seafood and environmental samples of Kerala. Listeria monocytogenes and L. innocua isolates were confirmed by multiplex PCR. L. monocytogenes isolates from the four positive samples showed phosphatidylinositol-specific phospholipase C reaction on Chromocult® Listeria selective agar. Molecular characterization of L. monocytogenes isolates for virulence genes revealed the presence of β-hemolysin (hly), plcA, actA, metalloprotease (mpl), iap and prfA genes in all the isolates recovered from the positive samples.
KeywordsListeria monocytogenes Tropical Seafood Virulence gene
The authors of this manuscript are thankful to the Director, Central Institute of Fisheries Technology for providing necessary facilities for carrying out this work. The authors also show their deep sense of gratitude to Dr. S.B. Barbuddhe, Senior Scientist, ICAR Research Complex, Goa for kindly donating two isolates of L. monocytogenes.
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