Acute Death of Kangaroos in a Zoo Due to Highly Pathogenic Corynebacterium pseudotuberculosis and Yersinia pseudotuberculosis

Abstract

Background: “Lumpy jaw” is disease effecting wallabies and kangaroos, particularly in Macropus rufus and Macropus giganteus. In the most serious situations, additional tooth loss and fistulas follow, accompanied by a stench, weight loss, and eventually death due to sepsis or blood poisoning. “Lumpy jaw” disease has seriously affected the normal display and health of kangaroos, and cause a huge economic loss. There was an outbreak of jaw infection in kangaroos at the Nanjing Forest Zoo. Two Macropus giganteus and two Macropus rufus died of “lumpy jaw”. The main objective of the describing case was to isolate pathogens, provide a basis for follow-up treatment, and serve to establish a disease prevention protocol.

Case: Four grown-up kangaroos (two Macropus giganteus and two Macropus rufus) were raised in Nanjing Forest Zoo, who had obviously clinical symptoms, such as oral lesions of pus, necrotic tissue, rotting teeth, then died of “lumpy jaw”. Oral swab samples were collected from the lesion sites of the dying kangaroos. Mice experiments were conducted to examine the pathogenicity of the strains. Tests of antimicrobial susceptibity were performed to prescribe with better drug treatments for kangaroos. Corynebacterium pseudotuberculosis and Yersinia pseudotuberculosis were identified based on morphology, culture characteristics and biochemical tests. Corynebacterium pseudotuberculosis (G⁺) in Sucrose, Mannitol, Lactose, Maltose, Glucose tubes were positive, that acids and gases both production, in Gelatin liquefaction, Indol test, MR were positive, that only acids production, others were negative; Yersinia pseudotuberculosis (G^-) in Urea, MR were positive, that only acids production, others were negative.The infected mice presented with gum erosion or ulcers when the two pathogens were injected subcutaneous at the oral regional by 2-3 point at 0.2 mL of individual strains（1.0×10⁹ CFU/mouse）. Drug sensitivity tests showed that Corynebacterium pseudotuberculosis is highly sensitive to Erythromycin (E) and Sulfamethoxazole (SMZ); meanwhile, Yersinia pseudotuberculosis is highly sensitive to Sulfamethoxazole (SMZ), Nitrofurantoin (N), Penicillin-G (P-G) and Erythromycin (E). The other “lumpy jaw” kangaroos in the zoo now receive oral screening with antibiotics (SMZ, E).

Discussion: Yersinia pseudotuberculosis is one of three pathogenic bacteria of the gram-negative genus Yersinia; it can be found in birdsand other mammals. It also spreads through soil, plants, and insects in the environment.Yersinia pseudotuberculosis can also lead to fatal systemic symptoms in human. Corynebacterium pseudotuberculosis belongs to the Actinobacteria family, which are associated with Caseous lymphadenitis in breeding animals, especially in goats and sheep. The isolates affected the lymph nodes and visceral organs of the kangaroos in this case, who presented with gingivitis or stomatitis. It is the first report of Corynebacterium pseudotuberculosis and Yersinia pseudotuberculosis co-infecting kangaroo and causing a fatal case of “lumpy jaw” in China. In this case, isolation and identification of pathogenic bacteria were carried out on the sick kangaroos, and animal test and drug susceptibity test were conducted. The study results could provide theoretical basis for the follow-up treatment and prevention method of this disease.