Overview
- Video
- Salmonella, a rod-shaped gram-negative bacterium belonging to the family of Enterobacteriaceae, is the causative agent of salmonellosis. Salmonellosis in warm-blooded vertebrates is in most cases associated with serovars of Salmonella enterica. The most common type of infection is the carrier state, in which infected animals carry the pathogen for a variable period of time without showing any clinical signs. Clinical disease is characterized by two major syndromes: a systemic septicemia (also termed as typhoid) and an enteritis. Other less common clinical presentations include abortion, arthritis, respiratory disease, necrosis of extremities, and meningitis.
- facultative intracellular pathogen is primarily an intestinal bacterium
Clinical signs
- As infection progresses, a true septicemia may follow, with subsequent localization in brain and meninges, pregnant uterus, joints and distal aspects of the limbs, and tips of the ears and tails, which can result, respectively, in meningoencephalitis, abortion, osteitis, and dry gangrene of the feet, tail, or ears. The organism also frequently localizes in the gallbladder and mesenteric lymph nodes, and survivors intermittently shed the organism in the feces.
- S Typhimurium is commonly associated with outbreaks of enteritis in calves <2 months old, whereas S Dublin has been associated with the same condition in older calves and adult cattle.