Diagnostic performance of fecal quantitative real-time polymerase chain reaction for detection of<i>Lawsonia intracellularis</i>–associated proliferative enteropathy in nursery pigs

Pedersen, Ken Steen; Stege, Helle; Jensen, Tim Kåre; Guedes, Roberto Maurício Carvalho; Ståhl, Marie; Nielsen, Jens Peter; Hjulsager, Charlotte Kristiane; Larsen, Lars Erik; Angen, Øystein

doi:10.1177/1040638713480499

Cited by 10 publications

(9 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The selection of herds and pigs, the herd examinations, the sample processing and the laboratory investigations have previously been reported [6, 7]. Feed type was recorded as home-mixed/purchased pelleted feed, while days post-weaning and days since the last change in feed were recorded on a continuous scale.…”

Section: Methodsmentioning

confidence: 99%

“…A number of additional laboratory investigations of the pigs not previously reported were performed using techniques previously described: colon tissue samples were examined for B. pilosicoli by fluorescent in-situ hybridisation (FISH) [8], jejunum content was examined for Rotavirus by ELISA, Salmonella spp. and E. coli [7], colon content was examined for Brachyspira spp [9], and faecal samples were subjected to qPCR testing for E. coli F4 and F18 genes [10]. …”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Herd diagnosis of low pathogen diarrhoea in growing pigs – a pilot study

et al. 2014

Self Cite

View full text Add to dashboard Cite

BackgroundThe major indication for antibiotic use in Danish pigs is treatment of intestinal diseases post weaning. Clinical decisions on antibiotic batch medication are often based on inspection of diarrhoeic pools on the pen floor. In some of these treated diarrhoea outbreaks, intestinal pathogens can only be demonstrated in a small number of pigs within the treated group (low pathogen diarrhoea). Termination of antibiotic batch medication in herds suffering from such diarrhoea could potentially reduce the consumption of antibiotics in the pig industry. The objective of the present pilot study was to suggest criteria for herd diagnosis of low pathogen diarrhoea in growing pigs.Data previously collected from 20 Danish herds were used to create a case series of clinical diarrhoea outbreaks normally subjected to antibiotic treatment. In the present study, these diarrhoea outbreaks were classified as low pathogen (<15% of the pigs having bacterial intestinal disease) (n =5 outbreaks) or high pathogen (≥15% of the pigs having bacterial intestinal disease) (n =15 outbreaks). Based on the case series, different diagnostic procedures were explored, and criteria for herd diagnosis of low pathogen diarrhoea were suggested. The effect of sampling variation was explored by simulation.ResultsThe diagnostic procedure with the highest combined herd-level sensitivity and specificity was qPCR testing of a pooled sample containing 20 randomly selected faecal samples. The criteria for a positive test result (high pathogen diarrhoea outbreak) were an average of 1.5 diarrhoeic faecal pools on the floor of each pen in the room under investigation and a pathogenic bacterial load ≥35,000 per gram in the faecal pool tested by qPCR. The bacterial load was the sum of Lawsonia intracellularis, Brachyspira pilosicoli and Escherichia coli F4 and F18 bacteria per gram faeces. The herd-diagnostic performance was (herd-level) diagnostic sensitivity =0.99, diagnostic specificity =0.80, positive predictive value =0.94 and negative predictive value =0.96.ConclusionsThe pilot study suggests criteria for herd diagnosis of low pathogen diarrhoea in growing pigs. The suggested criteria should now be evaluated, and the effect of terminating antibiotic batch medication in herds identified as suffering from low pathogen diarrhoea should be explored.Electronic supplementary materialThe online version of this article (doi:10.1186/2046-0481-67-24) contains supplementary material, which is available to authorized users.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Herd diagnosis of low pathogen diarrhoea in growing pigs – a pilot study

et al. 2014

Self Cite

View full text Add to dashboard Cite

show abstract

“…The prevalence of L. intracellularis in both normal and diarrheic feces and the quantitative load of L. intracellularis in the positive samples were similar to those previously reported in Danish growing pigs. 10,11 The performance of quantitative diagnostic tests is evaluated in terms of accuracy and precision. Lin concordance correlation coefficient evaluates both aspects and is computed based on 3 different parameters.…”

Section: Discussionmentioning

confidence: 99%

“…8 Excretion levels for L. intracellularis indicative of proliferative enteropathy have been reported, and qPCR could potentially be applied for the assessment of severity of infection with L. intracellularis in practice. 9,11 Pooling of fecal samples could reduce laboratory costs associated with qPCR testing for L. intracellularis. However, for L. intracellularis PCR testing of fecal samples, inhibition has been a matter of concern.…”

Section: Introductionmentioning

confidence: 99%

Pooling of porcine fecal samples for quantification of Lawsonia intracellularis by real-time polymerase chain reaction

et al. 2014

Self Cite

View full text Add to dashboard Cite

Abstract. Procedures in which biological specimens are mixed and tested as 1 sample (pooling) have been applied for various biological specimens and laboratory examinations. The objective of the current study was to investigate agreement between laboratory testing of fecal pools and theoretical values obtained by averaging test results from individual fecal samples in relation to a quantitative polymerase chain reaction (qPCR) test for Lawsonia intracellularis. Ten diarrheic and 10 normal fecal samples were submitted from each of 43 Danish swine herds (n = 860 fecal samples). Pools (n = 43), each containing 20 individual fecal samples from the same herd, were prepared in the laboratory by pooling 10% fecal phosphate buffered saline solutions. All pools and individual fecal samples were subjected to qPCR testing for L. intracellularis. The theoretical number of L. intracellularis in the pools was calculated as the mean number of bacteria from the 20 individual fecal samples contributing to each pool. Agreement between the laboratory testing of pools and theoretical calculations based on individual sample results was evaluated. Pooling resulted in fewer L. intracellularis-positive herds (41.9%) compared with testing 20 fecal samples (53.5%). Agreement between the laboratory and the theoretical pools for dichotomized test results was 100% (95% confidence interval: 91.8-100%). For the quantitative test results, Lin concordance correlation coefficient was 0.997. The mean difference between the laboratory testing and the theoretical values was not different from zero (mean difference = 0.039 log 10 bacteria/g feces; P = 0.26).

show abstract

“…A real-time PCR assay had a sensitivity of only 0.84 and specificity of 0.93 in detecting L. intracellularis infected swine feces. Therefore PCRs are not only less sensitive, expensive and require specialized facilities and equipment [7,10,18] but also have little value in predicting the optimal time for vaccine placement. Serological methods are relatively inexpensive and user-friendly and therefore are the first method of choice in screening swine herds for antibodies against L. intracellularis.…”

Section: Discussionmentioning

confidence: 99%

Evaluation and use of a serological assay for the detection of antibodies toLawsonia intracellularisin swine

Magtoto

Vegi

Wang

et al. 2014

International Journal of Veterinary Science and Medicine

View full text Add to dashboard Cite

Porcine proliferative enteropathy (PPE) is a common and economically important gastro-intestinal disease of swine caused by the intracellular bacterium, Lawsonia intracellularis. Conventional tests to detect antibody responses to L. intracellularis include the immuno-peroxidase monolayer assay (IPMA), immuno-fluorescent antibody test (IFAT) and a lipopolysaccharide ELISA (LPS-ELISA). These tests are not commercially available. Therefore, objective of this study is to evaluate the performance of a commercial L. intracellularis blocking ELISA. Performance of the commercial ELISA was compared to the IPMA and LPS-ELISA using serum from experimentally infected animals (N = 40). The prevalence of L. intracellularis sero-positive animals was assessed by comparing suspect and randomly selected sera (N = 394). The commercial ELISA, IPMA and a non-commercial lipopolysaccharide (LPS) LPS-ELISA showed a 95% correlation when tested using experimentally derived known status samples. When compared to the IPMA the sensitivity of the commercial ELISA was 91% while the specificity was 100%. Therefore, the diagnostic sensitivity and specificity of the commercial L. intracellularis ELISA was comparable to the LPS-ELISA and IPMA. A comparison of suspect and randomly selected field samples with the commercial ELISA indicated that L. intracellularis sero-positivity is widespread and does not correlate with possible disease status. ª 2014 Production and hosting by Elsevier B.V. on behalf of Faculty of Veterinary Medicine, Cairo University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/3.0/).Abbreviations: PPE, porcine proliferative enteropathy; IFAT, immuno-fluorescent antibody test; IPMA, immuno-peroxidase monolayer assay; ELISA, enzyme linked immunosorbent assay; LPS, lipopolysaccharide; IHC, immunohistochemistry; PCR, polymerase chain reaction

show abstract

Diagnostic performance of fecal quantitative real-time polymerase chain reaction for detection ofLawsonia intracellularis–associated proliferative enteropathy in nursery pigs

Cited by 10 publications

References 15 publications

Herd diagnosis of low pathogen diarrhoea in growing pigs – a pilot study

Herd diagnosis of low pathogen diarrhoea in growing pigs – a pilot study

Pooling of porcine fecal samples for quantification of Lawsonia intracellularis by real-time polymerase chain reaction

Evaluation and use of a serological assay for the detection of antibodies toLawsonia intracellularisin swine

Contact Info

Product

Resources

About