Comparative Pathology of Nocardiosis in Marine Mammals

• Published in: Veterinary pathology Vol. 46; no. 2; pp. 299 - 308
• Main Authors: St. Leger, J.A, Begeman, L, Fleetwood, M, Frasca, S, Garner, M.M, Lair, S, Trembley, S, Linn, M.J, Terio, K.A
• Format: Journal Article
• Language: English
• Published: United States American College of Veterinary Pathologists 2009
• Subjects: Adrenal Glands - microbiology; Adrenal Glands - pathology; animal pathology; Animals; bacterial pneumonia; Caniformia; Cerebellum - microbiology; Cerebellum - pathology; Cetacea; Delphinapterus leucas; Delphinidae; disease diagnosis; encephalitis; Female; killer whale; lesions (animal); Lung - microbiology; Lung - pathology; lungs; lymph nodes; Lymph Nodes - microbiology; Lymph Nodes - pathology; lymphadenitis; Male; marine mammals; Nocardia - classification; Nocardia - isolation & purification; Nocardia asteroides; Nocardia brasiliensis; Nocardia cyriacigeorgici; Nocardia farcinica; Nocardia Infections - pathology; Nocardia Infections - veterinary; Nocardia levis; Nocardia otitidiscaviarum; Orcinus orca; Pinnipedia; seals; Skin - microbiology; Skin - pathology; Thoracic Vertebrae - microbiology; Thoracic Vertebrae - pathology; Tursiops truncatus
• ISSN: 0300-9858; 1544-2217
• DOI: 10.1354/vp.08-VP-0209-S-FL

Nocardia spp. infections in mammals cause pyogranulomatous lesions in a variety of organs, most typically the lung. Members of the Nocardia asteroides complex are the most frequently recognized pathogens. Nine cases of nocardiosis in free-ranging pinnipeds and 10 cases of nocardiosis in cetaceans were evaluated. Host species included the hooded seal (Cystophora cristata, n = 8), leopard seal (Hydrurga leptonyx, n = 1), Atlantic bottlenose dolphin (Tursiops truncatus, n = 4), beluga whale (Delphinapterus leucas, n = 4), and killer whale (Orcinus orca, n = 2). The most common presentation of nocardiosis in both pinnipeds and cetaceans was the systemic form, involving 2 or more organs. Organs most frequently affected were lung and thoracic lymph nodes in 7 of 9 cases in pinnipeds and 8 of 10 cases in cetaceans. Molecular identification and bacterial isolation demonstrated a variety of pathogenic species. N. asteroides, N. farcinica, N. brasiliensis, and N. otitisdiscaviarum are pathogenic for pinnipeds. In cetaceans N. asteroides, N. farcinica, N. brasiliensis, N. cyriacigeorgica, and N. levis are pathogenic. Hematoxylin and eosin and acid fast staining failed to reveal bacteria in every case, whereas modified acid fast and Grocott's methenamine silver consistently demonstrated the characteristic organisms. In both pinnipeds and cetaceans, juvenile animals were affected more often than adults. Hooded seals demonstrated more cases of nocardiosis than other pinnipeds.