Detection of extracellular factor-positive Streptococcus suis serotype 2 strains in tonsillar swabs of live sows by PCR.
In this study, the sensitivity (Se) and specificity (Sp) of a PCR for the detection of EF-positive Streptococcus suis serotype 2 strains in tonsillar swabs of live sows were assessed. We sampled 471 sows originating from four farrow-to-finish farms by tonsillar swabbing and collected their tonsils after slaughter. On these specimens, a PCR, a bacterial examination (BE) or both were performed for the detection of EF-positive S. suis serotype 2 strains. Swab-PCR, Tonsil-PCR and Tonsil-BE were regarded as three integral tests. A Bayesian approach was used to calculate the Se and Sp of the tests. Se and Sp for Swab-PCR were 0.63 (95% credibility interval <0.52, 0.74>) and 0.96 (<0.92, 0.99>), respectively. Values for Se and Sp of Tonsil-PCR amounted to 0.88 (<0.75, 0.96>) and 0.94 (<0.87, 0.99>), respectively. For Tonsil-BE, Se was 0.65 (<0.51, 0.76>) and Sp was 0.97 (<0.91, 0.99>). Repetition of the swabbing procedure after 10 min resulted in a higher Se 0.85 (<0.67, 0.96>) than the Se of the first-Swab-PCR. Repetition of the PCR on the same sample did not result in any significant changes in the outcome of the analysis.
Swildens
Bas
B
Faculty of Veterinary Medicine, Department of Farm Animal Herd Health and Reproduction, P.O. Box 80151, Yalelaan 7, 3584 CL Utrecht 3058 TD, The Netherlands. b.swildens@vet.uu.nl
Wisselink
Henk J
HJ
Engel
Bas
B
Smith
Hilde E
HE
Nielen
Mirjam
M
Verheijden
Jos H M
JH
Stegeman
J Arjan
JA
D000818:Animals; D001499:Bayes Theorem; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005260:Female; D014066:Palatine Tonsil / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013290:Streptococcal Infections / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D017011:Streptococcus suis / Q000235:genetics / Q000302:isolation & purification*; D013552:Swine; D013553:Swine Diseases / Q000175:diagnosis / Q000382:microbiology*
D004269:DNA, Bacterial