{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,31]],"date-time":"2026-10-31T10:31:52Z","timestamp":1793442712492,"version":"4.5.0"},"reference-count":19,"publisher":"American Association of Avian Pathologists (AAAP)","issue":"2","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Avian Diseases"],"published-print":{"date-parts":[[2021,1,19]]},"abstract":"<jats:p>In April and November of 2018, multiple commercial laying hen flocks within the same company presented with a sharp increase in mortality and drop in egg production that persisted for several days. These flocks showed striking necropsy lesions consistent with systemic infection and responded to antimicrobial treatment in the feed. Staphylococcus aureus (SA) was the most frequently isolated organism from multiple tissues including comb and wattle lesions, lungs, liver, ovary, spleen, and bone marrow. Given such an uncommon presentation of SA, which is known as a secondary opportunistic pathogen, a challenge study was conducted to evaluate its role in these disease outbreaks. In the present study, laying hens of two ages (22 and 96 wk) were inoculated with SA via three routes: oral gavage, subcutaneous (SC) injection, and intravenous (IV) injection. Both young and old hens in the IV group showed a significant increase in body temperature and drop in body weight; however, the clinical signs observed in the naturally occurring outbreaks were not present. SA was reisolated at multiple time points postchallenge from all challenge groups except the negative control group. While the SC group showed localized necrosis at the injection site, microscopic changes were different from changes observed in birds from the natural outbreaks. Despite observed initial differences in route and age, the SA challenge strain was not capable of reproducing the disease on its own. The results of this study indicate that SA may have played a role in the increased mortality, clinical signs, and necropsy lesions reported with the naturally occurring outbreaks. However, SA should still be considered as a secondary opportunistic pathogen. Other factors that could have caused the initial insult are stress, immunosuppression, or other primary infectious agents. The results of this study may aid veterinary diagnosticians, clinicians, and all poultry professionals to include SA in their differentials list as a secondary opportunistic pathogen in similar cases. This is an uncommon presentation and further field observations and clinical studies are needed to better elucidate the pathogenesis of this disease, which will in turn help to prevent future outbreaks.<\/jats:p>","DOI":"10.1637\/0005-2086-65.2.310","type":"journal-article","created":{"date-parts":[[2021,6,22]],"date-time":"2021-06-22T00:49:48Z","timestamp":1624322988000},"page":"310-320","source":"Crossref","is-referenced-by-count":4,"title":["Comparison of Naturally Occurring vs. Experimental Infection of Staphylococcus aureus Septicemia in Laying Hens in Two Different Age Groups"],"prefix":"10.1637","volume":"65","author":[{"given":"Meaghan","family":"Meyer","sequence":"first","affiliation":[{"name":"Department of Animal Science, Iowa State University, Ames, IA 50011"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elizabeth","family":"Bobeck","sequence":"additional","affiliation":[{"name":"Department of Animal Science, Iowa State University, Ames, IA 50011"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuko","family":"Sato","sequence":"additional","affiliation":[{"name":"Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University College of Veterinary Medicine, Ames, IA 50011"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mohamed","family":"El-Gazzar","sequence":"additional","affiliation":[{"name":"Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University College of Veterinary Medicine, Ames, IA 50011"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1212","reference":[{"key":"7","doi-asserted-by":"crossref","unstructured":"D St\u0119pie\u0144-Py\u015bniak, J Wilczy\u0144ski, A Marek, et al.  \"Avian Pathol.\"  46, \"Staphylococcus simulans associated with endocarditis in broiler chickens.\" 44 (2017)","DOI":"10.1080\/03079457.2016.1203392"},{"key":"1","doi-asserted-by":"crossref","unstructured":"R Coates-Brown, JC Moran, P Pongchaikul, et al.  \"Front Microbiol.\"  9, \"Comparative genomics of Staphylococcus reveals determinants of speciation and diversification of antimicrobial defense.\" 2753 (2018)","DOI":"10.3389\/fmicb.2018.02753"},{"key":"3","doi-asserted-by":"crossref","unstructured":"T Takahashi, L Satoh, N Kikuchi,  \"Int J System Bacteriol.\"  49, \"Phylogenetic relationships of 38 taxa of the genus Staphylococcus based on 16s rRNA gene sequence analysis.\" 725 (1999)","DOI":"10.1099\/00207713-49-2-725"},{"key":"6","doi-asserted-by":"crossref","unstructured":"AA Al-Rubaye, MB Couger, S Ojha, et al.  \"PLOS ONE.\"  10, \"Genome analysis of Staphylococcus agnetis, an agent of lameness in broiler chickens.\" e0143336 (2015)","DOI":"10.1371\/journal.pone.0143336"},{"key":"8","doi-asserted-by":"crossref","unstructured":"MA Awan  and M Matsumoto  \"Poult Sci.\"  77, \"Heterogeneity of staphylococci and other bacteria isolated from six-week-old broiler chickens.\" 944 (1998)","DOI":"10.1093\/ps\/77.7.944"},{"key":"9","doi-asserted-by":"crossref","unstructured":"JR Andreasen, CB Andreasen, M Anwer, et al.  \"Avian Dis.\"  37, \"Heterophil chemotaxis in chickens with natural staphylococcal infections.\" 284 (1993)","DOI":"10.2307\/1591650"},{"key":"11","doi-asserted-by":"crossref","unstructured":"D Santivatr, SK Maheswaran, JA Newman, et al.  \"Avian Dis.\"  25, \"Effect of infectious bursal disease virus infection on the phagocytosis of Staphylococcus aureus by mononuclear phagocytic cells of susceptible and resistant strains of chickens.\" 303 (1981)","DOI":"10.2307\/1589924"},{"key":"13","doi-asserted-by":"crossref","unstructured":"J. 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Andreasen,  \"Diseases of poultry.\"  \"Staphylococcosis.\" 995 (2020)"},{"key":"5","doi-asserted-by":"crossref","unstructured":"K Hermans, LA Devriese, F Haesebrouck,  \"Pathogenesis of bacterial infections in animals.\"  \"Staphylococcus.\" 75 (2010)","DOI":"10.1002\/9780470958209.ch5"},{"key":"10","unstructured":"LA Newberry, DG Lindsey, JN Beasley, et al.  \"Proceedings of 45th North Carolina Avian Disease Conference.\"  \"A summary of data collected from turkeys following acute hemorrhagic enteritis virus infection at different ages.\" 63 (1994)"},{"key":"12","unstructured":"AA Bickford  and AS Rosenwald  \"Poult Dig.\"  \"Staphylococcal infections in chickens.\" 285 (1975)"},{"key":"14","unstructured":"K Fries-Craft, MM Meyer, Y Sato, et al.  \"Front Vet Sci.\"  \"Age and Staphyolococcus aureus inoculation route differentially alters metabolic potential and immune cell populations in laying hens.\""},{"key":"15","unstructured":"\"Version 9.4.\"  (2016)"},{"key":"16","unstructured":"\"Version 3.5.2.\"  (2018)"}],"container-title":["Avian Diseases"],"original-title":[],"link":[{"URL":"https:\/\/bioone.org\/journals\/avian-diseases\/volume-65\/issue-2\/0005-2086-65.2.310\/Comparison-of-Naturally-Occurring-vs-Experimental-Infection-of-Staphylococcus-aureus\/10.1637\/0005-2086-65.2.310.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,31]],"date-time":"2026-10-31T09:50:09Z","timestamp":1793440209000},"score":1,"resource":{"primary":{"URL":"https:\/\/bioone.org\/journals\/avian-diseases\/volume-65\/issue-2\/0005-2086-65.2.310\/Comparison-of-Naturally-Occurring-vs-Experimental-Infection-of-Staphylococcus-aureus\/10.1637\/0005-2086-65.2.310.full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,1,19]]},"references-count":19,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2021,6,1]]}},"URL":"https:\/\/doi.org\/10.1637\/0005-2086-65.2.310","relation":{},"ISSN":["0005-2086","1938-4351"],"issn-type":[{"value":"0005-2086","type":"print"},{"value":"1938-4351","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,1,19]]}}}