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Detection of Salmonella spp. in small ruminants using immunoassy and PCR


Bonke, R; Wacheck, S; Stüber, E; Stephan, R; Fredriksson-Ahomaa, M (2012). Detection of Salmonella spp. in small ruminants using immunoassy and PCR. Journal of Food Safety and Food Quality, 63(6):175-178.

Abstract

Salmonellosis is still one of the leading foodborne zoonotic diseases. Culture-based methods for detection of Salmonella spp. are laborious and can take up to seven days to obtain final results. Accurate and rapid methods for Salmonella screening in livestock are important to improve food safety. In this study, the occurrence of Salmonella spp. was studied in 80 pooled samples and fecal samples collected from healthy small ruminants at slaughter using the VIDAS® SLM immunoassay and SYBRGreen® based real-time PCR. Positive samples were subcultivated onto xylose-lysine-desoxycholate (XLD) and hectoen-enteric (HE) agar plates. The detection rate of Salmonella spp. was significantly higher by VIDAS® than by PCR. This pathogen was detected in 85 % and 48 % of the tonsil samples by VIDAS® and PCR, respectively. In total, 70 % of the fecal samples were positive by VIDAS® but only 5 % by PCR. Salmonella spp. was isolated only from samples, which were highly positive (test values >3.00) by VIDAS®. High positive VIDAS® test values (> 3.00) were only obtained in tonsil samples. Most (26/28) of the VIDAS®-positive fecal samples had very low test values (0.23―1.00). These fecal samples were all culture negative and could thus not be confirmed as true positives. The detection rate of Salmonella spp. in sheep tonsils was high with both VIDAS® and PCR methods. Salmonella spp. was isolated from 55 % of the tonsil samples. The goat tonsil samples were mostly (11/14) weak positive with VIDAS® (0.23―1.00); only two samples were PCR positive and one culture positive. Further research using more effective culture methods is needed to exclude possible false-positive results obtained by VIDAS®. More information is also needed about the significance of goats as a reservoir for Salmonella.

Abstract

Salmonellosis is still one of the leading foodborne zoonotic diseases. Culture-based methods for detection of Salmonella spp. are laborious and can take up to seven days to obtain final results. Accurate and rapid methods for Salmonella screening in livestock are important to improve food safety. In this study, the occurrence of Salmonella spp. was studied in 80 pooled samples and fecal samples collected from healthy small ruminants at slaughter using the VIDAS® SLM immunoassay and SYBRGreen® based real-time PCR. Positive samples were subcultivated onto xylose-lysine-desoxycholate (XLD) and hectoen-enteric (HE) agar plates. The detection rate of Salmonella spp. was significantly higher by VIDAS® than by PCR. This pathogen was detected in 85 % and 48 % of the tonsil samples by VIDAS® and PCR, respectively. In total, 70 % of the fecal samples were positive by VIDAS® but only 5 % by PCR. Salmonella spp. was isolated only from samples, which were highly positive (test values >3.00) by VIDAS®. High positive VIDAS® test values (> 3.00) were only obtained in tonsil samples. Most (26/28) of the VIDAS®-positive fecal samples had very low test values (0.23―1.00). These fecal samples were all culture negative and could thus not be confirmed as true positives. The detection rate of Salmonella spp. in sheep tonsils was high with both VIDAS® and PCR methods. Salmonella spp. was isolated from 55 % of the tonsil samples. The goat tonsil samples were mostly (11/14) weak positive with VIDAS® (0.23―1.00); only two samples were PCR positive and one culture positive. Further research using more effective culture methods is needed to exclude possible false-positive results obtained by VIDAS®. More information is also needed about the significance of goats as a reservoir for Salmonella.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:05 Vetsuisse Faculty > Institute of Food Safety and Hygiene
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:2012
Deposited On:12 Mar 2013 09:05
Last Modified:05 Apr 2016 16:37
Publisher DOI:https://doi.org/10.2376/0003-925X-63-175
Official URL:http://www.journal-food-safety.de/html/themen_2012.html

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