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Studies on the prevalence and molecular characterization of Listeria spp. Isolated From Foods of Animal Origin

KrishiKosh

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Title Studies on the prevalence and molecular characterization of Listeria spp. Isolated From Foods of Animal Origin
 
Creator Nayak, D.N.
 
Contributor Savalia, C.V.
 
Subject bacteria, sampling, animal husbandry, antibiotics, meat, genes, polysaccharides, productivity, biological phenomena, livestock
 
Description The present study was undertaken with the prime objective of isolating and identifying Listeria spp. from various foods of animal origin sold at retail shops/ markets in the city of Navsari, located within jurisdiction of Navsari Agricultural University, Gujarat.
The samples comprised of milk, milk products, meat and fish (50 each) collected aseptically from local market which were subjected first to pre enrichment/ enrichment in LEB, Fraser or UVM broth depending on type of the sample and the procedure adopted (as the case may be) followed by plating on three selective media viz; PALCAM, Oxford and McBride agar. In addition, human clinical samples were also screened as per standard isolation procedure. The colonies showing the typical colony characteristics were further identified upto species level on the basis of their microscopic, morphological and biochemical characteristics. Cultures identified as Listeria were further subjected to in vitro pathogenicity tests, detection of different virulence associated genes and sensitivity to different antibiotics.
Of the 200 food samples; 18 (9%) samples were found positive for Listeria spp. The species isolated were L.seeligeri (6/18), L.innocua (5/18), L.welshimeri (4/18) and L. monocytogenes (3/18). Highest prevalence was observed in milk samples with 8 samples showing presence of Listeria spp. Human clinical samples were negative for Listeria spp. Species wise, 6 isolates of L. seeligeri were isolated, two each from cow and buffalo milk and two from meat samples, 5 isolates of L. innocua of which four were present in fish and one in meat, 4 L. welshimeri isolates of which two were from ice cream samples and one each from buffalo milk and meat and 3 isolates of L. monocytogenes from milk (1 cow and 2 buffalo milk).
Listeria isolates recovered from various food samples showed cent per cent sensitivity towards Ampicillin. A quite high number of isolates were sensitive to Tetracycline (88.89%), followed by Chloramphenicol, Ciprofloxacin and Trimethoprim with a sensitivity of 55.56 per cent each. All the isolates showed 100 per cent resistance towards Cephalexin and a high number showed resistance towards Gentamicin (55.56%) followed by Trimethoprim (44.44%), Ciprofloxacin (33.33%) and Chloramphenicol and Tetracycline (11.11%).
All the Listeria isolates were screened for the presence or absence of virulence genes viz. inlA, inlB, plcA, plcB, actA, hlyA, iap, and prfA using specific primers. Isolates identified as L. monocytogenes revealed presence of all virulence genes suggesting the prevalence in foods of animal origin
 
Date 2016-04-30T15:20:58Z
2016-04-30T15:20:58Z
2014
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/65692
 
Language en
 
Format application/pdf
 
Publisher NAU