
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.
pathology
microbiology
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\/Wild\/Hawaiian monk seal\/cropped-images\/hms-wild-photo-1-c-noaa-pifsc-hmsrp-35-0-1270-992-1759760452.jpg","alt":"A Hawaiian monk seal rests on its side on a sandy beach.","title":"Where Do Hawaiian Monk Seals Live? And Other \u2018\u012alio Holo I Ka Uaua Trivia","link_url":"https:\/\/www.marinemammalcenter.org\/news\/where-do-hawaiian-monk-seals-live-and-other-ilio-holo-i-ka-uaua-trivia","label":"News Update","date":"2025-10-06 00:00:00"}

Where Do Hawaiian Monk Seals Live? And Other ‘Īlio Holo I Ka Uaua Trivia
October 6, 2025
Read More{"image":"\/Animals\/Patients\/California sea lions\/2025\/cropped-images\/dottie-csl-photo-by-bill-hunnewell-218-0-1270-992-1759777087.jpg","alt":"California sea lion","title":"LA Times: Marine mammals are dying in record numbers along the California coast","link_url":"https:\/\/www.marinemammalcenter.org\/news\/la-times-marine-mammals-are-dying-in-record-numbers-along-the-california-coast","label":"In the News","date":"2025-10-03 02:00:00"}

LA Times: Marine mammals are dying in record numbers along the California coast
October 3, 2025
Read More{"image":"\/People\/Action\/Veterinary care\/cropped-images\/dane-whitaker-and-emily-whitmer-vaccine-trial-by-bill-hunnewell-49-0-1270-992-1757364612.jpg","alt":"Two veterinarians collect a blood sample from an elephant seal in a rehabilitation pen.","title":"Bird Flu Vaccine Trial May Offer Hope for Protecting Hawaiian Monk Seals","link_url":"https:\/\/www.marinemammalcenter.org\/news\/bird-flu-vaccine-trial-may-offer-hope-for-protecting-hawaiian-monk-seals","label":"News Update","date":"2025-09-09 09:13:00"}

Bird Flu Vaccine Trial May Offer Hope for Protecting Hawaiian Monk Seals
September 9, 2025
Read More{"image":"\/Animals\/Patients\/Elephant seals\/2025\/cropped-images\/es-vaccine-trial-satellite-tag-by-bill-hunnewell-218-0-1270-992-1757432410.jpg","alt":"Northern elephant seal","title":"The New York Times: Scientists Begin Testing Bird Flu Vaccine in Seals","link_url":"https:\/\/www.marinemammalcenter.org\/news\/the-new-york-times-scientists-begin-testing-bird-flu-vaccine-in-seals","label":"In the News","date":"2025-09-09 02:00:00"}

The New York Times: Scientists Begin Testing Bird Flu Vaccine in Seals
September 9, 2025
Read More