The use of culture, pooled samples and PCR for identification of herds infected withBrachyspira hyodysenteriae

Abstract

AbstractThe sensitivity of culturingBrachyspira hyodysenteriaewas determined after sampling with swabs from porcine fecal specimens inoculated with tenfold dilutions of a field strain of these microbes. After storage of swabs,Brachyspira hyodysenteriaewas recovered throughout the first 3 weeks after inoculation from feces with more than 140 cells/g. Viable spirochetes could still be recovered after up to 83 days of storage from feces, with 1.4 × 106cells or more per gram. Culture forBrachyspiraspp. was performed on 285 rectal swabs, which were pooled in batches of five. The number of pooled samples positive forB. hyodysenteriaecorresponded with the sum results of individual analysis of the corresponding collections of five samples. A PCR system based on thetlyA gene ofB.hyodysenteriaewas developed and tested on primary cultures of pooled samples. The results of the PCR assay showed a 97% correlation with the culture results. The prevalence ofBrachyspiraspp. was determined in five swine herds and found to be highest among breeding gilts and boars aged 13–16 weeks and among 6–12-week-old weaned pigs. In contrast,Brachyspiraspp. were only rarely found in sows, which may reflect the development of immunity by adult pigs to all species of the genus.