Infectious necrotic hepatitis caused by Clostridium novyi type B in a horse: case report and review of the literature

Abstract

A 14-y-old bay Quarter Horse gelding was presented with progressive neurologic signs, elevated rectal temperature, and icterus for 3 d prior to death. Postmortem examination revealed icterus, large amounts of serosanguineous fluid in the abdominal cavity, widespread petechiae and ecchymoses in several organs, and a large, pale, and well-demarcated focus of necrosis in the liver. Histologically, there was coagulative necrosis surrounded by a rim of inflammatory cells and large numbers of gram-positive rods, which were identified as Clostridium novyi by immunohistochemistry. Liver samples tested by PCR were positive for C. novyi type B flagellin and alpha toxin genes, but negative for Clostridium haemolyticum and other clostridia. Based on postmortem findings and ancillary tests, a definitive diagnosis of infectious necrotic hepatitis (INH) was made. Mostly a disease of ruminants, also known as black disease, INH has rarely been reported in horses, and a definitive etiologic diagnosis has not been achieved previously; the etiology of all cases reported to date was identified as C. novyi but the type was not determined. Animals are predisposed to clostridial hepatitis when hepatic anaerobiosis is established. Such conditions allow germination and proliferation of bacterial spores, resulting in production and release of toxins. INH, caused by C. novyi type B, and bacillary hemoglobinuria, caused by C. haemolyticum, are mechanistically and pathologically almost indistinguishable. Because these 2 microorganisms are closely related, differentiation requires molecular tools.

Characterization of Clostridium novyi isolated from a sow in a sudden death case in Korea

“…The isolation and identification of C. novyi is rarely successful because specimens must be delivered to laboratories very quickly under strict anaerobic conditions [12,13,15]. In addition, samples should be processed within 12 h of the death of pigs for accurate diagnosis and successful isolation of C. novyi before the proliferation of other bacteria in the carcass [11,12,16].…”

Characterization of Clostridium novyi isolated from a sow in a sudden death case in Korea

“…The isolation and identification of C. novyi is rarely successful because specimens must be delivered to laboratories very quickly under strict anaerobic conditions (12,13,15). In addition, samples should be processed within 12 hours of the death of pigs for accurate diagnosis and successful isolation of C. novyi before the proliferation of other bacteria in the carcass (11,12,16).…”

Characterization of Clostridium novyi isolated from a sow in a sudden death case in Korea

“…Alpha toxin is produced and released by the vegetative forms of C. novyi type B, and its monoglycosyltransferase activity inactivates several GTP-binding proteins in cells, resulting in modification and redistribution of the actin cytoskeleton. For these reasons, necrosis occurs in the liver, and the cut surface of the affected liver exhibits a sponge-like appearance (19)(20)(21)(22)(23)(24). Glycosyltransferases were detected in the genome of the C. novyi isolate, indicating that the C. novyi isolate produces alpha toxin.…”

“…Subsequently, the endospores are spread to other organs. The endospores germinate and produce toxins in organs when anaerobic conditions form (19).…”