Cross-sectional study of calves from Norwegian dairy herds with enzootic pneumonia: pathogen occurrence, antimicrobial resistance, culture result interpretation, and sampling site agreement

Cross-sectional study of calves from Norwegian dairy herds with enzootic pneumonia: pathogen occurrence, antimicrobial resistance, culture result interpretation, and sampling site agreement | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Cross-sectional study of calves from Norwegian dairy herds with enzootic pneumonia: pathogen occurrence, antimicrobial resistance, culture result interpretation, and sampling site agreement Lise Marie Ånestad, Silje Enge Falkeid, Veslemøy Sunniva Oma, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6534677/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 13 You are reading this latest preprint version Abstract Background Enzootic pneumonia in calves is associated with pathogens such as Pasteurellaceae bacteria and Mycoplasmopsis bovis . Some of these bacteria are commensals in healthy calves, complicating culture interpretation, discouraging laboratory diagnostic use, and limiting knowledge of their impact. This study aimed to investigate the occurrence and antimicrobial resistance pattern of respiratory pathogens in calves from dairy herds with enzootic pneumonia. Culture results between upper and lower airway sites in healthy and sick calves were also compared to evaluate their diagnostic value. A cross-sectional study was conducted on 131 calves (72 healthy and 59 sick) from nine Norwegian dairy herds. Nasal swabs (NS), nasopharyngeal swabs (NPS), and serum were obtained from each calf, and bronchoalveolar lavage (BAL) from 113 calves. Results At the calf level, Pasteurella multocida was present in 60%, Mannheimia haemolytica in 55%, and Histophilus somni in 3%. At the sampling site level, from NS, NPS, and BAL, P. multocida was detected in 47%, 45%, and 27%, and M. haemolytica in 46%, 37%, and 8%, respectively. H. somni was detected in ≤ 2% per site. P. multocida appeared as pure culture in 73% (22/30) of positive BAL cultures. Serum antibodies to M. bovis were not detected. Disc diffusion showed that most Pasteurellaceae isolates were susceptible to penicillin and other common pneumonia antimicrobials. The exceptions were penicillin-resistant M. haemolytica isolates in two calves. Logistic regression identified dominant, abundant cultures of P. multocida from BAL as the only bacterial risk factor for pneumonia. Agreement for P. multocida detection between NS and NPS cultures and BAL was fair (kappa). Positive predictive values of P. multocida culture results at different abundance levels in NS and NPS, relative to BAL, were at most 49%. Conclusion P. multocida was the predominant bacterium in lungs of calves from problem herds, and its abundance in the lungs may differentiate infection from colonization in sick calves. M. haemolytica and H. somni appeared to have less clinical impact. Antimicrobial resistance appeared not to be a problem. Upper airway cultures were inaccurate predictors of bacterial presence and abundance in the lungs, and must be interpreted carefully alongside other diagnostic tools. bovine respiratory disease dairy calves Pasteurella multocida Mannheimia haemolytica penicillin nasal swab nasopharyngeal swab bronchoalveolar lavage diagnostics bacterial abundance Full Text Additional Declarations No competing interests reported. Supplementary Files Additionalfile1.docx Additionalfile2.docx Additionalfile3.docx Additionalfile4.docx Additionalfile5.docx Additionalfile6.docx Additionalfile7.docx Additionalfile8.docx Additionalfile9.docx Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 28 Apr, 2026 Reviews received at journal 14 Apr, 2026 Reviewers agreed at journal 13 Apr, 2026 Reviewers agreed at journal 10 Apr, 2026 Reviewers agreed at journal 08 Apr, 2026 Reviewers agreed at journal 08 Apr, 2026 Reviews received at journal 17 Jul, 2025 Reviewers agreed at journal 11 Jul, 2025 Reviewers invited by journal 08 Jul, 2025 Editor assigned by journal 21 May, 2025 Editor invited by journal 18 May, 2025 Submission checks completed at journal 16 May, 2025 First submitted to journal 16 May, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6534677","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":467593292,"identity":"305e5d4a-8e18-4be0-b859-32a46d9fe1ce","order_by":0,"name":"Lise Marie Ånestad","email":"data:image/png;base64,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","orcid":"","institution":"Norwegian Veterinary Institute","correspondingAuthor":true,"prefix":"","firstName":"Lise","middleName":"Marie","lastName":"Ånestad","suffix":""},{"id":467593293,"identity":"94915146-4698-4fb1-ad2c-c36b73f6827d","order_by":1,"name":"Silje Enge Falkeid","email":"","orcid":"","institution":"Norwegian University of Life Sciences","correspondingAuthor":false,"prefix":"","firstName":"Silje","middleName":"Enge","lastName":"Falkeid","suffix":""},{"id":467593294,"identity":"13614d22-f31c-47ce-b627-f750573477f9","order_by":2,"name":"Veslemøy Sunniva Oma","email":"","orcid":"","institution":"Norwegian University of Life Sciences","correspondingAuthor":false,"prefix":"","firstName":"Veslemøy","middleName":"Sunniva","lastName":"Oma","suffix":""},{"id":467593295,"identity":"bfa22c27-7854-4c80-a26d-b0278263d2cf","order_by":3,"name":"Randi Therese Garmo","email":"","orcid":"","institution":"TINE SA","correspondingAuthor":false,"prefix":"","firstName":"Randi","middleName":"Therese","lastName":"Garmo","suffix":""},{"id":467593296,"identity":"bb3eb973-a917-4d0c-a43c-082f9242e6d4","order_by":4,"name":"Ane Mohn Bjelland","email":"","orcid":"","institution":"Norwegian Institute of Public Health","correspondingAuthor":false,"prefix":"","firstName":"Ane","middleName":"Mohn","lastName":"Bjelland","suffix":""},{"id":467593297,"identity":"742009b2-6806-41c9-a2b7-81faf3d2cce2","order_by":5,"name":"Amelia R. 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Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"bovine respiratory disease, dairy calves, Pasteurella multocida, Mannheimia haemolytica, penicillin, nasal swab, nasopharyngeal swab, bronchoalveolar lavage, diagnostics, bacterial abundance","lastPublishedDoi":"10.21203/rs.3.rs-6534677/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6534677/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eEnzootic pneumonia in calves is associated with pathogens such as \u003cem\u003ePasteurellaceae\u003c/em\u003e bacteria and \u003cem\u003eMycoplasmopsis bovis\u003c/em\u003e. Some of these bacteria are commensals in healthy calves, complicating culture interpretation, discouraging laboratory diagnostic use, and limiting knowledge of their impact. This study aimed to investigate the occurrence and antimicrobial resistance pattern of respiratory pathogens in calves from dairy herds with enzootic pneumonia. Culture results between upper and lower airway sites in healthy and sick calves were also compared to evaluate their diagnostic value. A cross-sectional study was conducted on 131 calves (72 healthy and 59 sick) from nine Norwegian dairy herds. Nasal swabs (NS), nasopharyngeal swabs (NPS), and serum were obtained from each calf, and bronchoalveolar lavage (BAL) from 113 calves.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eAt the calf level, \u003cem\u003ePasteurella multocida\u003c/em\u003e was present in 60%, \u003cem\u003eMannheimia haemolytica\u003c/em\u003e in 55%, and \u003cem\u003eHistophilus somni\u003c/em\u003e in 3%. At the sampling site level, from NS, NPS, and BAL, \u003cem\u003eP. multocida\u003c/em\u003e was detected in 47%, 45%, and 27%, and \u003cem\u003eM. haemolytica\u003c/em\u003e in 46%, 37%, and 8%, respectively. \u003cem\u003eH. somni\u003c/em\u003e was detected in \u0026le;\u0026thinsp;2% per site. \u003cem\u003eP. multocida\u003c/em\u003e appeared as pure culture in 73% (22/30) of positive BAL cultures. Serum antibodies to \u003cem\u003eM. bovis\u003c/em\u003e were not detected. Disc diffusion showed that most \u003cem\u003ePasteurellaceae\u003c/em\u003e isolates were susceptible to penicillin and other common pneumonia antimicrobials. The exceptions were penicillin-resistant \u003cem\u003eM. haemolytica\u003c/em\u003e isolates in two calves. Logistic regression identified dominant, abundant cultures of \u003cem\u003eP. multocida\u003c/em\u003e from BAL as the only bacterial risk factor for pneumonia. Agreement for \u003cem\u003eP. multocida\u003c/em\u003e detection between NS and NPS cultures and BAL was fair (kappa). Positive predictive values of \u003cem\u003eP. multocida\u003c/em\u003e culture results at different abundance levels in NS and NPS, relative to BAL, were at most 49%.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003e \u003cem\u003eP. multocida\u003c/em\u003e was the predominant bacterium in lungs of calves from problem herds, and its abundance in the lungs may differentiate infection from colonization in sick calves. \u003cem\u003eM. haemolytica\u003c/em\u003e and \u003cem\u003eH. somni\u003c/em\u003e appeared to have less clinical impact. Antimicrobial resistance appeared not to be a problem. Upper airway cultures were inaccurate predictors of bacterial presence and abundance in the lungs, and must be interpreted carefully alongside other diagnostic tools.\u003c/p\u003e","manuscriptTitle":"Cross-sectional study of calves from Norwegian dairy herds with enzootic pneumonia: pathogen occurrence, antimicrobial resistance, culture result interpretation, and sampling site agreement","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-24 12:17:31","doi":"10.21203/rs.3.rs-6534677/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-28T14:17:34+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-14T17:00:35+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"219978563389398087837801063163470978842","date":"2026-04-13T06:58:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"306317828217559934096885830286899558466","date":"2026-04-10T16:05:22+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"339560442385657161394135241969176745737","date":"2026-04-09T00:03:17+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"104879295098474432074890584778575200835","date":"2026-04-08T16:20:54+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-17T16:21:26+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"166783708158219194381769034468453280314","date":"2025-07-11T17:44:14+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-07-09T03:39:18+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-21T14:43:26+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-05-19T02:53:34+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-05-16T21:29:14+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Veterinary Research","date":"2025-05-16T21:28:10+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-veterinary-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [BMC Veterinary Research](http://bmcvetres.biomedcentral.com/)","snPcode":"12917","submissionUrl":"https://submission.nature.com/new-submission/12917/3?","title":"BMC Veterinary Research","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e2a8e2af-3389-4faf-9472-c02d41daf2d7","owner":[],"postedDate":"June 24th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-08T12:39:49+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-24 12:17:31","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6534677","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6534677","identity":"rs-6534677","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}