Comparison of Diagnostic Detection Methods for Mycobacterium avium subsp. paratuberculosis in North American Bison

Abstract

Tissues and fecal material were collected from 14 North American bison ( Bison bison) that were suspected of having Johne's disease and analyzed for the presence of Mycobacterium avium subsp. paratuberculosis (M. paratuberculosis). Sections of ileum, ileal-cecal lymph node, and three sequential sections of jejunum with their associated mesenteric lymph nodes were taken from each animal. Fecal culture indicated that 5 of 14 (35.7%) animals were infected, whereas cultures from tissues detected 12 of 14 (85.7%) animals as infected and 59 of 111 (53.2%) of the tissues as positive for M. paratuberculosis. Polymerase chain reaction analysis identified infection in 14 of 14 (100%) animals and in 91 of 112 (81.2%) tissues. In addition, tissues were processed for Ziehl-Neelsen acid-fast staining, auramine O/acridine orange fluorescent staining, and immunohistochemical staining. Ziehl-Neelsen and auramine O staining identified 7 of 14 (50%) and 5 of 14 (35.7%) animals as infected and 24 of 112 (21.4%) and 28 of 112 (25%) tissues as positive, respectively. Immunohistochemical analyses of bison tissues, using antisera collected from rabbits immunized with four different preparations of M. paratuberculosis, identified a greater percentage of infected animals (ranging from 57 to 93%) and positive tissues (ranging from 28 to 46%). Collectively, these data indicate that DNA-based detection of M. paratuberculosis was more sensitive than bacterial culture or staining, identified infection in all the bison, and detected the greatest number of positive tissues within each animal.