In vivo isolation of Salmonella choleraesuis from porcine neutrophils.

Seventy-five pigs from 4 facilities were examined for Salmonella choleraesuis by use of bacteriologic culture of feces, blood, WBC (buffy coat), mononuclear leukocytes, and neutrophils. The organism was isolated from 0 of 75 fecal samples, compared with isolation from 39 of 75 purified neutrophil preparations. Of the pigs that did not have Salmonella isolated from feces or blood, but had S choleraesuis isolated from neutrophils, 6 were further examined. These pigs from 2 groups again had culture performed at least 3 successive times to test for repeatability and to determine optimal number of neutrophils required for Salmonella isolation. These same pigs were euthanatized and necropsied. Nineteen tissue specimens from each pig were obtained for culture, but S choleraesuis was isolated only from neutrophil samples. Results indicate that neutrophils may contribute to the carrier state in pigs and should be cultured when attempting to identify S choleraesuis carrier swine.

Desferoxamine and iron dextran in acute Salmonella cholerae-suis infection in pigs.

Serum iron (SI)-related and hematologic changes were evaluated in a herd of weaned pigs inoculated with a strain of Salmonella cholerae-suis, causing 83% mortality within 22 days after inoculation was done. Serum iron concentrations decreased to 35% of base-line values 2 days after inoculation was done, but recovered to near base line subsequently. Total SI-binding capacity (TIBC) decreased gradually for 14 days after inoculation was done. Transferrin (TF) concentrations decreased to near half the base line throughout the postinoculation observation period. The calculated SI saturation coefficient decreased to half the base line, but recovered to or above the base-line value subsequently. Combined observations of SI, TIBC, TF, and SI saturation coefficient concentrations indicated that there was higher saturation of host iron-binding proteins and recruitment of additional iron-binding systems subsequent to 2 days after inoculation was done. Day 2 after inoculation seemed to be a critical period for host iron metabolism. Injection of supplemental iron dextran simultaneously with Salmonella infection resulted in lower mortality of iron-injected pigs (P less than 0.005). A highly significant negative correlation was observed between SI concentration and rectal temperatures after pigs were inoculated with Salmonella (r = -0.54; P less than 0.0001). Hemoglobin concentrations, mean corpuscular volume, and mean corpuscular hemoglobin were not significantly affected by Salmonella infection or iron injection concurrent with Salmonella infection.(ABSTRACT TRUNCATED AT 250 WORDS)