Hypervirulent Klebsiella Pneumoniae in California Sea Lions: Pathologic Findings in Natural Infections
- Infectious disease
- Pathology
- Microbiology
Abstract
Tissues of stranded California sea lions (Zalophus californianus) naturally infected with a hyperviruluent strain of Klebsiella pneumoniae were examined by histopathology and immunohistochemistry against the K. pneumoniae K2 capsular antigen. In 7 of 8 animals, there was severe purulent bronchopneumonia, sometimes complicated by fibrinonecrotizing pleuritis with pyothorax. In affected areas of lung, large numbers of degenerate neutrophils and macrophages were admixed with rare large extracellular and intracellular gram-negative bacilli surrounded by a prominent capsule. Through serotyping, polymerase chain reaction, sequencing, and immunohistochemistry, these bacteria were confirmed to be a K2 serotype of K. pneumoniae. The same bacteria were identified through double immunolabeling within macrophages in blood vessels, lymph nodes, spleen, and liver. Intact K. pneumoniae were identified on epithelial surfaces of the nasopharyngeal, tracheal, and small intestine mucosae and within distal renal tubules. Our findings indicate that hypervirulent K. pneumoniae causes severe respiratory disease and intrahistiocytic bacteremia in California sea lions.
Seguel, M., Gottdenker, N.L., Colegrove, K., Johnson, S., Struve, C., Howerth, E.W. 2017. Hypervirulent Klebsiella pneumonia in California sea lions (Zalophus californianus): Pathologic findings in natural infections. Veterinary Pathology 54(5): 846-850.
Related Publications
{"image":"\/Animals\/Wild\/Other species\/nz-sea-lion-shutterstock.jpg","alt":"New Zealand sea lion","title":"Causes of Death in Two Populations of New Zealand Sea Lions","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/causes-of-death-in-two-populations-of-new-zealand-sea-lions","label":"Research Paper"}
{"image":"\/Animals\/Patients\/California sea lions\/csl-by-bill-hunnewell-c-the-marine-mammal-center-6.jpg","alt":"California sea lions","title":"Zoonotic Bacteria Persistence and Susceptibility","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/zoonotic-bacteria-persistence-and-susceptibility","label":"Research Paper"}
{"image":"\/Animals\/Patients\/California sea lions\/cropped-images\/csl-photo-by-bill-hunnewell-c-the-marine-mammal-center-1-0-0-2358-1722-1600891644.jpg","alt":"California sea lions","title":"Emerging Viruses in Marine Mammals","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/emerging-viruses-in-marine-mammals","label":"Research Paper"}
{"image":"\/Animals\/Patients\/California sea lions\/csl-photo-by-bill-hunnewell-c-the-marine-mammal-center-12.jpg","alt":"two California sea lions","title":"Multi-Phase Muscle Breakdown in California Sea Lions","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/multi-phase-muscle-breakdown-in-california-sea-lions","label":"Research Paper"}
Recent News
{"image":"\/Animals\/Patients\/Elephant seals\/2025\/cropped-images\/elefante-es-photo-by-bill-hunnewell-104-0-1270-992-1767832647.jpg","alt":"Elefante \u2013 Northern elephant seal","title":"Rescue Stories: Vote for Your Favorite Marine Mammal Patient of 2025!","link_url":"https:\/\/www.marinemammalcenter.org\/news\/rescue-stories-vote-for-your-favorite-marine-mammal-patient-of-2025","label":"News Update","date":"2026-01-16 10:05:08"}
Rescue Stories: Vote for Your Favorite Marine Mammal Patient of 2025!
January 16, 2026
Read More{"image":"\/People\/Action\/Veterinary care\/cropped-images\/Harris_Green turtle_TMMC-0-0-1270-992-1767649941.jpg","alt":"Heather Harris","title":"Seattle Aquarium Awards Dr. Heather Harris With Prestigious Conservation Research Award","link_url":"https:\/\/www.marinemammalcenter.org\/news\/seattle-aquarium-awards-dr-heather-harris-with-prestigious-conservation-research-award","label":"In the News","date":"2026-01-05 04:48:00"}
Seattle Aquarium Awards Dr. Heather Harris With Prestigious Conservation Research Award
January 5, 2026
Read More{"image":"\/People\/Action\/Veterinary care\/cropped-images\/harris-teaching-tube-feeding-0-0-1270-992-1767650122.jpg","alt":"A veterinarian and two trained volunteers tube feed an elephant seal pup.","title":"Training College Students in Marine Mammal Health","link_url":"https:\/\/www.marinemammalcenter.org\/news\/training-college-students-in-marine-mammal-health","label":"News Update","date":"2026-01-05 04:48:00"}
{"image":"\/Animals\/Patients\/Harbor seals\/2013\/cropped-images\/hs-bogey-photo-by-Ingrid-Overgard-c-the-marine-mammal-center-382-0-2914-2276-1605061447.jpg","alt":"harbor seal Bogey","title":"Top Eco Friendly Valentine\u2019s Day Gifts","link_url":"https:\/\/www.marinemammalcenter.org\/news\/top-eco-friendly-valentines-day-gifts","label":"News Update","date":"2026-01-01 01:00:00"}
