
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\/Patients\/Harbor seals\/cropped-images\/hs-group-with-hats-photo-by-bill-hunnewell-c-the-marine-mammal-center-34-0-1270-992-1750873865.jpg","alt":"Four harbor seals with small ID tags on their heads swim in a rehabilitation pool.","title":"How Our Patients are Named and Identified","link_url":"https:\/\/www.marinemammalcenter.org\/news\/how-our-patients-are-named-and-identified","label":"Patient Update","date":"2025-06-26 02:00:00"}

{"image":"\/Animals\/Wild\/Gray whale\/cropped-images\/gray-whale-oreo-by-josie-slaathaug-c-the-marine-mammal-center-108-0-1270-992-1750880575.jpg","alt":"Gray whale fluke above the water","title":"Los Angeles Times: The numbers of gray whales migrating along the California coast continue to plummet","link_url":"https:\/\/www.marinemammalcenter.org\/news\/los-angeles-times-the-numbers-of-gray-whales-migrating-along-the-california-coast-continue-to-plummet","label":"In the News","date":"2025-06-25 02:00:00"}

Los Angeles Times: The numbers of gray whales migrating along the California coast continue to plummet
June 25, 2025
Read More{"image":"\/Animals\/Wild\/Harbor seal\/cropped-images\/harbor-seal-pup-photo-by-Ruvim-Miksanskiy-251-0-1270-992-1750880392.jpg","alt":"Harbor seal pup resting on the beach","title":"ABC7 San Francisco: Animal trauma could be linked to bad human behavior, Bay Area marine mammal experts say","link_url":"https:\/\/www.marinemammalcenter.org\/news\/abc7-san-francisco-animal-trauma-could-be-linked-to-bad-human-behavior-bay-area-marine-mammal-experts-say","label":"In the News","date":"2025-06-24 02:00:00"}

ABC7 San Francisco: Animal trauma could be linked to bad human behavior, Bay Area marine mammal experts say
June 24, 2025
Read More{"image":"\/People\/Action\/Response\/cropped-images\/mbo-crew-es-rope-rescue-photo-by-lesley-simms-c-the-marine-mammal-center-2-0-0-1270-992-1749571082.jpg","alt":"MBO crew carrying a crate up a cliff","title":"The Marine Mammal Center reports high levels of marine mammal disturbance in Central and Northern California for third year in a row","link_url":"https:\/\/www.marinemammalcenter.org\/news\/the-marine-mammal-center-reports-high-levels-of-marine-mammal-disturbance-in-central-and-northern-california-for-third-year-in-a-row","label":"Press Release","date":"2025-06-10 02:00:00"}

The Marine Mammal Center reports high levels of marine mammal disturbance in Central and Northern California for third year in a row
June 10, 2025
Read More