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Author: SRAVANTHI, MANNEM × End date: 2010 × Start date: 2010 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    MOLECULAR DETECTION AND CONTROL OF SALMONELLA IN ANIMAL FEEDS
    (Sri Venkateswara Veterinary University, TIRUPATI – 517 502,A.P, 2010-10) SRAVANTHI, MANNEM; ESWARA PRASAD, P (Major); SUDHAKARA REDDY, K; SREENIVASULU, D; ADILAXMAMMA, K
    ABSTRACT : Feed and feed ingredients serve as a carrier for a range of bacteria, which can adversely affect the performance of animal. One such important contaminant of feeds is Salmonella species. Traditional cultural methods used for identification of Salmonella involves use of pre-enrichment, selective enrichment broths (Selenite cystine broth or Rappaport Vassiliadis broth), selective enrichment media (BGA, MCA, XLD etc.) and confirmation of isolates by biochemical tests. Among 109 feed samples tested, seven (6.42%) positive Salmonella isolates were obtained. The incidence of Salmonella contamination in animal feed samples was screened as 10.81% in Kadapa where as 4.4% in Chittoor district. The traditional cultural methods used for Salmonella isolation were time consuming. Among the several alternate analysis strategies, Polymerase Chain Reaction has been found to be a highly specific molecular diagnostic tool. PCR technique was standardized targeting fimA gene of Salmonella. A 29 cycle PCR reaction with an annealing temperature of 58°C and MgCl2 concentration of 3 mM were found optimum for amplification of 85 bp product of fimA gene. To overcome the production losses due to the presence of bacteria in feed samples, suitable control methods have to be followed. Three different control methods viz., formaldehyde treatment, UV treatment and sun drying were adopted. Formaldehyde at two concentrations (0.5% and 1%) and UV light at a wavelength range of 250-260 nm for 10 minutes were used for treatments. Feed samples were kept for sun drying for a period of 6 days. After treatments, feed samples were again processed for Salmonella isolation and total plate counts. All the three treatment methods were effective in completely decreasing the Salmonella levels in feed samples. For reducing total bacterial counts formaldehyde treatment found to be the most effective method, followed by UV treatment and sun drying. ABST was carried out to determine the drugs, effective for the therapy of Salmonella. The drugs, ofloxacin, ciprofloxacin, and ceftriaxone were found to be effective for all isolates of Salmonella. The results of the experiment conclude that PCR technique with fimA gene is found to be effective in detecting Salmonella from feed samples at a shorter time and 1% formaldehyde treatment is highly effective in reducing the total counts of bacteria. Results of ABST conducted indicated ofloxacin, ciprofloxacin and ceftriaxone are highly effective against Salmonella as compared to the other antibiotics.