ENTEROTOXIN ACTIVITY OF A SALMONELLA-TYPHIMURIUM OF EQUINE ORIGIN INVIVO IN RABBITS AND THE EFFECT OF SALMONELLA CULTURE LYSATES AND CHOLERA-TOXIN ON EQUINE COLONIC MUCOSA INVITRO

  • 1 April 1986
    • journal article
    • research article
    • Vol. 47  (4) , 769-773
Abstract
To determine whether a strain of Salmonella typhimurium (UCD 1755) of equine origin had enterotoxin activity, 2 ml of a cell-free culture lysate of strain UCD 1755 and approximately 109 viable strain UCD 1755 organisms were inoculated into ligated small intestinal segments of rabbits. Intestinal seqments inoculated with viable strain UCD 1755 organisms and those inoculated with a cell-free culture lysate of strain UCD 1755 had significant (P < 0.05) accumulation of fluid 10 hours after inoculation when compared with ligated intestinal segments either inoculated with sterile-heart infusion broth or left empty. There was not a statistically significant difference between fluid accumulation of intestinal segments inoculated with viable strain UCD 1755 and that of segments inoculated with a cell-free culture lysate of strain UCD 1755. The responses of equine colonic mucosa to culture filtrates of 2 strains of Salmonella typhimurium (UCD 1755 and SL 1027) and purified cholera toxin were studied in vitro. Isolated samples of colonic mucosa were incubated for 4 hours at 37.degree. C in Krebs-Henseleit bicarbonate buffer (KHB) alone, KHB plus culture lysate of strain UCD 1755, KHB plus culture lysate of strain SL 1027, and KHB plus 1 .mu.g of cholera toxin/ml. Cyclic adenosine monophosphate (cAMP) content of each sample was determined. Mucosa incubated in KHB plus cholera toxin had a significantly (P < 0.01) greater cAMP content than did mucosa incubated in KHB alone. Mucosa incubated in either KHB plus strain UCD 1755 culture lysate or KHB plus strain SL 1027 lysate had a greater cAMP content than did mucosa incubated in KHB alone, but the difference was not significant.