Prevalence of Listeria spp. in Traditional Indian Dairy Products from Chennai Metropolis, Tamil Nadu

Abstract

The present study was conducted between September, 2014 and June, 2015 to assess the prevalence of Listeria monocytogenes in Traditional Indian Dairy Products from Chennai, Tamil Nadu. Samples of Ghee, Rasagolla, Gulabjamun, Curd and Payasam were screened for the presence of L. monocytogenes using conventional culture method and validated by PCR. Among the 150 samples screened, 50 isolates from different dairy products (22 gulabjamun, 22 rasagolla and 06 curd samples) were presumptively identified as Listeria spp. Further confirmation by biochemical characterization and hemolysis on blood agar revealed that 34 isolates were Listeria welshimeri, 10 were L. murrayi and 06 were identified as L. seeligiri. The 34 isolates of L. welshimeri were present in 14 gulabjamun, 14 rasagolla and 06 curd samples. Similarly, 10 isolates of L. murrayi have been found in 04 gulabjamun and 06 rasagolla samples. L. seeligiri isolates were identified from 04 gulabjamun and 02 rasagolla samples. None of the Listeria species were found in ghee and payasam samples and interestingly, the results of both methods revealed that none of the traditional products screened were positive for L. monocytogenes.