Assessment of different cut-off values of the ELISA-Typhimurium for the discrimination of swine herds with Salmonella isolation

Kich, Jalusa Deon; Costa, Eduardo de Freitas; Triques, N.; Niogueira, Mariana; Costa, O. A. Dalla; Coldebella, Arlei; Kummer, Aline; Cardoso, Marisa Ribeiro de Itapema

doi:10.5433/1679-0359.2016v37n5p3107

Cited by 3 publications

(2 citation statements)

References 9 publications

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“…Moreover, a high number of the sampled pigs were carrying Salmonella in their guts. Serology gives historical information [26,27], thus a positive result in the ELISA-Typhimurium test cannot be interpreted as an active infection at slaughter, but indicates that the pig was infected on the farm. However, seropositive pig batches have higher chances of including carrier individuals, which may be excreting Salmonella at slaughter [4,7,40].…”

Section: Discussionmentioning

confidence: 99%

Enumeration, Antimicrobial Resistance and Typing of Salmonella enterica: Profile of Strains Carried in the Intestinal Contents of Pigs at Slaughter in Southern Brazil

Paim

Pissetti

Vieira

et al. 2019

Acta Scientiae. Vet.

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Background: Despite a strong association between Salmonella isolation and slaughter hygiene, as measured by the Enterobacteriaceae levels on pre-chill carcass surfaces, a high variation in this association was observed between sampling days within the same slaughterhouse. It was hypothesised that in a scenario of high exposure on the farm, batches with a high prevalence of carrier pigs shedding a high number of Salmonella may enhance the risk of contamination on some slaughter days. Thus, the aim of this study was to assess the profile of Salmonella carried in the intestinal contents of slaughter pigs.Materials, Methods & Results: Ten pig batches slaughtered in a slaughterhouse were investigated for the presence of Salmonella. From each pig, the following samples were taken: i. blood collected at bleeding; ii. sponges rubbed on the carcass surface after bleeding and before chilling; iii. fragment of the ileocecal region of the intestine. Serum samples were subjected to a ELISA-Typhimurium test. Sponges were investigated for the presence of Salmonella and total aerobic mesophilic (TAM) and Enterobacteriaceae (EC) bacterial counts. Salmonella was enumerated in the intestinal contents. Selected Salmonella strains were subjected to an antimicrobial resistance disk diffusion test, macro-restriction with Xba-I (PFGE) and whole genome sequencing (WGS). From the 50 sampled pigs, 96% were positive in the ELISA-Typhimurium test and 64% were Salmonella-positive in the intestinal contents. The amount of Salmonella in the intestinal content samples was highly variable, and the mean log of fitted distributions of Salmonella in the batch ranged from -2.97 to 2.25 cfu.g-1. The slaughter process achieved a logarithmic reduction, ranging from 0.64 to 2.35 log cfu.cm-2 for TAM and from 0.55 to 2.57 log cfu.cm-2 for EC. Salmonella was isolated from 16% of the carcasses after bleeding; this frequency decreased to 8% at the pre-chill step. All positive pre-chill carcasses originated from pigs carrying Salmonella in the intestinal content and from batches with a high number of carrier pigs. Salmonella Typhimurium and its monophasic variant were the most frequent in the intestinal contents and carcasses. Resistance was detected against ampicillin (42.5%), tetracycline (42.5%), sulfonamide (40%), gentamicin (25%) and ciprofloxacin (12.5%). Regarding colistin, 85% of the tested strains were classified as non-susceptible. The monophasic variant S. Typhimurium strains subjected to PFGE and WGS presented different profiles; several antimicrobial resistance genes were identified and all belonged to ST-19.Discussion: In this study, almost all sampled pigs entering the slaughter line had been exposed to Salmonella on the farm and a high number were carrying Salmonella in their guts. While the three batches with Salmonella-positive carcasses at the pre-chill step presented TAM media that was not significantly different from the other batches, there was a higher number of positive pigs carrying Salmonella in their intestinal contents. Moreover, the batch with the highest number of positive carcasses also presented the highest Salmonella mean count in their intestinal contents. The profile of Salmonella carried in the intestinal content of slaughter pigs proved to be highly variable in terms of the frequency, number of bacteria, serovars, antimicrobial resistance, and genotypes. Results indicate that the day-to-day variability in the prevalence and number of Salmonella in the intestinal contents of slaughter batches is likely to influence the frequency of contaminated pre-chill carcasses. Salmonella Typhimurium isolated from the intestinal contents of slaughter pigs may belong to genotypes involved in human disease and may carry several antimicrobial resistance genes. These aspects should be taken into account when planning Salmonella control in swine.

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Section: Discussionmentioning

confidence: 99%

Enumeration, Antimicrobial Resistance and Typing of Salmonella enterica: Profile of Strains Carried in the Intestinal Contents of Pigs at Slaughter in Southern Brazil

Paim

Pissetti

Vieira

et al. 2019

Acta Scientiae. Vet.

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“…Serum samples were tested by the ELISA-Typhimurium test as previously described (KICH et al, 2007). The cut-off point of the test was the OD 0.169 (KICH et al, 2016). Sponges were individually suspended in 30 mL of buffered peptone water 1%, and 5 mL of suspension was used for Total Aerobic Mesophilic (TAM) enumeration in Plate Count Agar (PCA) (DOWNES et al, 2011).…”

Section: Methodsmentioning

confidence: 99%

Detection of Salmonella Heidelberg resistant to colistin in the intestinal content of pigs at slaughter

Werlang

Paim

Vieira

et al. 2017

International Conference on the Epidemiology and Control of Biological, Chemical and Physical Hazards in Pigs and Pork

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Salmonella Heidelberg has increasingly been reported as cause of human salmonellosis worldwide. In Brazil, S. Heidelberg has been reported in poultry but it is infrequently isolated from pigs. Here, we describe the isolation of S. Heidelberg resistant to colistin from slaughter pigs. Five pigs and their carcasses belonging to a same slaughter batch in ten consecutive days were sampled for fragment of intestine in the ileocecal region and sponges rubbed on the carcass surface (400 cm 2) before chilling. Salmonella detection was performed according to the ISO 6579:2002. Intestinal content was also subjected to Salmonella enumeration by a miniaturized Most Probable Number (MPN) protocol. Salmonella isolates were characterized by antimicrobial resistance by the disk diffusion test, the minimum inhibitory concentration to colistin determination and to gene mcr-1 investigation by PCR. Salmonella was isolated from the intestinal content of 64% (32/50) of the pigs, in amounts that varied from 2.7 to >1,400 MPN/g. Salmonella Heidelberg was the most frequent serovar identified in the intestinal content samples (20/50; 40%), and this serovar was present in eight of the ten pig batches sampled. At the prechill, Salmonella was isolated from 8% of carcasses, and S. Heidelberg was not detected. Salmonella Heidelberg strains were resistant against ampicillin (n=9), tetracycline (n=8), sulfonamide (n=8) and gentamicin (n=5). Nine multi-drug resistant strains were detected; among them four strains were positive for the gene mcr-1. In these strains the MIC value was 8 µg.mL-1 , while in the strains without the mcr-1 gene it ranged from 2 µg.mL-1 to 4 µg.mL-1. Therefore, humans in contact with carrier pigs or their environment may be exposed to S. Heidelberg, including strains harboring the gene mcr-1.

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Comparison of Meat Juice Serology and Bacteriology for Surveillance of Salmonella in the Brazilian Pork Production Chain

Viana

Sereno

Bersot

et al. 2020

Foodborne Pathogens and Disease

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This study assessed an ELISA based assay to detect Salmonella in swine as a potential tool to predict the presence of Salmonella in swine carcasses. Also, the research evaluated if meat juice can be used as an alternative to blood serum as a matrix for ELISA. The following samples were collected from ten batches of swine: blood (n = 100); environment (barn floor, n = 10, and lairage floor, n = 10); meat juice (n = 100, obtained after defrosting of diaphragm); tonsils (n = 100); mesenteric lymph nodes (n = 100); and carcasses after bleeding (n = 100), after singeing (n = 100), after evisceration (n = 100), and after final rinsing (n = 100). Blood and meat juice were subjected to ELISA to detect antibodies against Salmonella, and other samples were subjected to Salmonella detection by ISO 6579. Salmonella was detected in 3 samples from barn floors, 7 lairage floors, 45 tonsils, 43 mesenteric lymph nodes and in 3 carcasses. Based on ELISA, Salmonella positive samples were: 86 and 46 blood serum (20% and 40% cut-offs) and 68 and 46 meat juice (20% and 40% cut-offs). Optical density (OD) readings from blood serum and meat juice presented a high and significant correlation (r = 0.93, P < 0.001), and a substantial agreement for Salmonella detection (K = 0.69, ELISA 40% cut-off). ELISA and microbiological detection presented an absence or poor agreement for Salmonella detection from different samples of the same pig carcass, with the exception of results obtained by ELISA 40% cut-off from blood serum and meat juice with mesenteric lymph nodes (K = 0.49 and 0.50, respectively) and tonsils (K = 0.29 and 0.30, respectively).Meat juice can be considered an alternative to blood serum as a matrix for ELISA in order to allow preliminary detection of Salmonella in mesenteric lymph nodes and tonsils, allowing the identification of potential sources of contamination during slaughtering.

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Assessment of different cut-off values of the ELISA-Typhimurium for the discrimination of swine herds with Salmonella isolation

Cited by 3 publications

References 9 publications

Enumeration, Antimicrobial Resistance and Typing of Salmonella enterica: Profile of Strains Carried in the Intestinal Contents of Pigs at Slaughter in Southern Brazil

Enumeration, Antimicrobial Resistance and Typing of Salmonella enterica: Profile of Strains Carried in the Intestinal Contents of Pigs at Slaughter in Southern Brazil

Detection of Salmonella Heidelberg resistant to colistin in the intestinal content of pigs at slaughter

Comparison of Meat Juice Serology and Bacteriology for Surveillance of Salmonella in the Brazilian Pork Production Chain

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