{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:30:31Z","timestamp":1760059831300,"version":"build-2065373602"},"reference-count":37,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2025,7,15]],"date-time":"2025-07-15T00:00:00Z","timestamp":1752537600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"U.S. Fish &amp; Wildlife Service\u2019s Wildlife and Sport Fish Restoration","award":["F22AF002266 AZ FW-100-P-30"],"award-info":[{"award-number":["F22AF002266 AZ FW-100-P-30"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Pathogens"],"abstract":"<jats:p>Nocardia spp. are opportunistic pathogens of humans, domestic animals, and wildlife that can cause high levels of morbidity and mortality. Here, we present a unique case of nocardial airsacculitis in a free-ranging mallard (Anas platyrhynchos) from Arizona, USA, and compare it to the hosts, geographic distribution, diagnostic methodology, and infection site of known nocardiosis cases in birds. A gross necropsy, histopathology, and bacterial culture were performed. There were no gross findings associated with the nocardiosis. Histopathology showed multiple granulomas expanding the air sac with intralesional filamentous bacteria that were Grocott\u2019s methenamine silver-positive, Fite\u2013Faraco and Ziehl\u2013Neelsen acid-fast, positive with the Periodic acid\u2013Schiff reaction, and variably Gram-positive. The organism was isolated in culture and identified as Nocardia cyriacigeorgica based on the sequencing of a 463 bp portion of the 16S rRNA gene. While reports of nocardiosis in the class Aves are rare and some are possibly misdiagnosed due to limited diagnostics, cases are reported globally, sometimes resulting in epizootics. More information is needed to understand whether immunosuppression plays a role in disease development in birds. Known to be an emerging pathogen in humans, N. cyriacigeorgica can be considered as a differential diagnosis for pulmonary and potentially cutaneous or disseminated infections in birds.<\/jats:p>","DOI":"10.3390\/pathogens14070698","type":"journal-article","created":{"date-parts":[[2025,7,15]],"date-time":"2025-07-15T11:52:58Z","timestamp":1752580378000},"page":"698","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Nocardia cyriacigeorgica in a Mallard (Anas platyrhynchos) from Arizona, USA"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0254-6491","authenticated-orcid":false,"given":"Susan","family":"Knowles","sequence":"first","affiliation":[{"name":"U.S. Geological Survey, 6006 Schroeder Road, Madison, WI 53711, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7922-8352","authenticated-orcid":false,"given":"Brenda M.","family":"Berlowski-Zier","sequence":"additional","affiliation":[{"name":"U.S. Geological Survey, 6006 Schroeder Road, Madison, WI 53711, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4626-8339","authenticated-orcid":false,"given":"Anne","family":"Justice-Allen","sequence":"additional","affiliation":[{"name":"Arizona Game and Fish Department, 5000 W. Carefree Highway, Phoenix, AZ 85086, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Barbara L.","family":"Bodenstein","sequence":"additional","affiliation":[{"name":"U.S. Geological Survey, 6006 Schroeder Road, Madison, WI 53711, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2239-1252","authenticated-orcid":false,"given":"Jeffrey M.","family":"Lorch","sequence":"additional","affiliation":[{"name":"U.S. Geological Survey, 6006 Schroeder Road, Madison, WI 53711, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,7,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Churgin, S.M., Teng, J.L.L., Ho, J.H.P., Graydon, R., Martelli, P., Lee, F.K., Hui, S.W., Fong, J.Y.H., Lau, S.K.P., and Woo, P.C.Y. (2019). 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