Clinical and genomic features of Listeria monocytogenes-associated mesenteric lymphadenitis in a cat

BACKGROUND

Listeriosis is a severe foodborne infection caused by Listeria monocytogenes, an important foodborne pathogen of animals and humans. Listeriosis is a rare disease in cats.

OBJECTIVE

To describe the clinical, diagnostic imaging, histological, and microbiological features of L. monocytogenes-associated mesenteric lymphadenitis in a cat.

ANIMALS

Listeria monocytogenes-associated mesenteric lymphadenitis was confirmed in a cat by histology and microbiology.

RESULTS

Two distinct isolates of L. monocytogenes were cultured from the affected mesenteric lymph node and whole genome sequencing was performed.

CONCLUSION AND CLINICAL IMPORTANCE

This report should alert veterinary clinicians and microbiologists to the syndrome, which may have implications for health and food safety in animals and humans.

Paraintestinal mesenteric abscess and chronic peritonitis in a bull

A 2-year-old bull was examined because of intermittent anorexia, signs of mild colic, and weight loss of 3 weeks' duration. A tympanitic resonance (ping) could be heard during simultaneous auscultation and percussion of the right paralumbar fossa, and a mass could be felt in the right dorsal quadrant of the abdominal cavity during palpation per rectum. Right flank laparotomy was performed, and intraoperative ultrasonography and ultrasound-guided fine-needle aspiration were used to determine that the mass was an abscess. However, the abscess could not be removed or drained into the colon because of extensive adhesions to other organs. Because the owner refused to pursue continued medical treatment, the bull was euthanatized. At necropsy, the abscess was found to be connected to a caudal mesenteric lymph node through a fistula. Histologic evaluation of the lymph node revealed hyperplastic lymphadenitis, and an alpha-hemolytic streptococcus was recovered from the abscess fluid. The most likely possibility for the findings in this bull were that the lymphadenitis was of hematogenous origin and that the abscess developed as a direct extension of the infectious process, similar to development of mesenteric abscesses in horses with chronic streptococcal infection (i.e., strangles).

Intestinal and pulmonary mycotic lymphadenitis in cattle

Among 4877 slaughtered cattle with tuberculosis-like lesions in lymph nodes, 94 cases (1.9 per cent) revealed fungal hyphae on histopathological examination. The survey period was 12 years and most of the affected animals (greater than 77 per cent) were beef cattle. Affected nodes were mesenteric in 84 cases (89.4 per cent), mediastinal and/or bronchial in seven cases (7.4 per cent), and in three cases (3.2 per cent), both mesenteric and mediastinal nodes were affected. The incidence of mycotic lymphadenitis was unrelated to year of study or season. Eighty-two of the cases were re-examined histologically and immunohistochemically. All lesions were granulomatous in nature and, in 26 cases, eosinophilic asteroid bodies (rosette formation) around hyphae were found. In 75 cases, immunofluorescence staining identified the agent as a zygomycete, probably Absidia corymbifera and, in one case, there was a concurrent infection with a Candida species. In seven cases that did not react with the antibodies employed, a diagnosis of zygomycosis was suggested on the basis of hyphal morphology. Hyphae of Aspergillus spp. were not found in any of the lesions. A concurrent fungal and mycobacterial infection (M. avium) was diagnosed in one case. Thus, zygomycetes are the main cause of macroscopically apparent mycotic lymphadenitis, a sporadic disease most probably caused by feeding with mouldy food stuffs.

Avian mycobacteriosis in three horses

The clinical, bacteriologic and pathologic findings of three adult horses suffering from avian tuberculosis are presented. Chronic weight loss and hypoproteinemia were pertinent clinical abnormalities in all three horses. Gross pathologic lesions were characterized by chronic enterocolitis with mesenteric lymphadenopathy in two horses and hepatic granulomas in the third horse. The microscopic diagnoses were chronic, non-caseating granulomatous enterocolitis, and necrotizing, non-mineralizing granulomatous hepatitis, respectively. All three horses had granulomatous lymphadenitis of mesenteric lymph nodes with varying degrees of non-mineralizing, coagulation necrosis. Various serotypes of the Mycobacterium avium-intracellulare complex were isolated from selected tissues and feces.

Mesenteric lymphadenitis of swine caused by Rhodococcus sputi

Rhodococcus sputi caused tuberculosislike lymphadenitis of mesenteric lymph nodes in swine. This is the first study reporting that R. sputi can be a pathogen in swine.