Systematic Veterinary Bacteriology and Mycology

DIAGNOSIS

• Gram stained smears can be made from the mucosa of the small intestine of a recently dead animal.
• Large numbers of Gram-positive rods are suggestive of C.welchii.
• Saccharolytic in Robertson's cooked meat media, opalescence in egg yolk agar, haemolysis on blood agar, stormy clot fermentation and sugar fermentation tests are helpful for identification.
• Histopathology on brain sections helps to demonstrate focal symmetrical encephalomalacia in pulpy kidney disease.
• Rapid kidney autolysis, pulpy cortical softening and Glucosuria are suggestive of pulpy kidney disease.

Demonstration of toxin in the small intestine

• Collect 20-30ml of ileal contents from a recently dead animal and send it to the laboratory as soon as possible.
• The ileal contents are centrifuged and the clear supernatant is tested for toxin.
• In ileal contents, the epsilon and iota toxins are usually in the active form.
• To demonstrate the toxin 0.4ml of the clarified ileal content can be inoculated i/v ly into mice.
• If mouse dies within 5 mts this is probably due to shock. Death from toxin usually occurs within 10hrs.
• Identification of toxin in the clarified ileal content is carried out by a neutralization test by using suitable antitoxin.