{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T17:10:15Z","timestamp":1785431415174,"version":"3.56.0"},"reference-count":46,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T00:00:00Z","timestamp":1783555200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001807","name":"S\u00e3o Paulo Research Foundation","doi-asserted-by":"publisher","award":["2021\/09134-6"],"award-info":[{"award-number":["2021\/09134-6"]}],"id":[{"id":"10.13039\/501100001807","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001807","name":"S\u00e3o Paulo Research Foundation","doi-asserted-by":"publisher","award":["2021\/05400-3"],"award-info":[{"award-number":["2021\/05400-3"]}],"id":[{"id":"10.13039\/501100001807","id-type":"DOI","asserted-by":"publisher"}]},{"award":["2021\/09134-6"],"award-info":[{"award-number":["2021\/09134-6"]}],"id":[{"id":"https:\/\/ror.org\/02ddkpn78","id-type":"ROR","asserted-by":"publisher"}]},{"award":["2021\/05400-3"],"award-info":[{"award-number":["2021\/05400-3"]}],"id":[{"id":"https:\/\/ror.org\/02ddkpn78","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Veterinary Sciences"],"abstract":"<jats:p>Antimicrobial resistance (AMR) is a global concern partly driven by excessive antimicrobial use (AMU) in animal production. Clinical mastitis (CM) is a leading cause of AMU in dairy farms, highlighting its importance from a public-health perspective. This observational study aimed to evaluate the use of antimicrobial susceptibility testing as a criterion for selecting antimicrobials for the treatment of mild and moderate CM in dairy cows. To this end, the association between in vitro antimicrobial susceptibility test results of mastitis-causing pathogens and in vivo bacteriological cure (BC) was assessed. A total of 340 cows with mild or moderate CM from 14 commercial dairy herds in Brazil were enrolled in the study. Isolates from the pretreatment milk samples were subjected to antimicrobial susceptibility testing (AST) using agar disk diffusion. Susceptibility results and cow-level variables were included in a generalized linear mixed model (GLMM) to evaluate their association with BC. No significant association was found between the antimicrobial susceptibility results and BC of the mastitis cases. In conclusion, although in vitro susceptibility testing remains an important tool for AMR surveillance, the findings of this study suggest that its utility in guiding antimicrobial treatment decisions in CM cases is limited.<\/jats:p>","DOI":"10.3390\/vetsci13070667","type":"journal-article","created":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T10:16:22Z","timestamp":1783592182000},"page":"667","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Association Between Antimicrobial Susceptibility Test Results and Bacteriological Cure of Mild and Moderate Bovine Clinical Mastitis"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0188-5595","authenticated-orcid":false,"given":"Breno Luis","family":"Nery Garcia","sequence":"first","affiliation":[{"name":"Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4205-1423","authenticated-orcid":false,"given":"Carlos Eduardo","family":"Fidelis","sequence":"additional","affiliation":[{"name":"Department of Animal Nutrition and Production, School of Veterinary Medicine and Animal Science, University of S\u00e3o Paulo, Pirassununga 13635-900, S\u00e3o Paulo, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-7318-1407","authenticated-orcid":false,"given":"Kristian da Silva","family":"Barbosa","sequence":"additional","affiliation":[{"name":"Department of Animal Nutrition and Production, School of Veterinary Medicine and Animal Science, University of S\u00e3o Paulo, Pirassununga 13635-900, S\u00e3o Paulo, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2708-5414","authenticated-orcid":false,"given":"Gustavo","family":"Freu","sequence":"additional","affiliation":[{"name":"Department of Animal Nutrition and Production, School of Veterinary Medicine and Animal Science, University of S\u00e3o Paulo, Pirassununga 13635-900, S\u00e3o Paulo, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4273-3494","authenticated-orcid":false,"given":"Marcos Veiga dos","family":"Santos","sequence":"additional","affiliation":[{"name":"Department of Animal Nutrition and Production, School of Veterinary Medicine and Animal Science, University of S\u00e3o Paulo, Pirassununga 13635-900, S\u00e3o Paulo, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,9]]},"reference":[{"key":"ref_1","unstructured":"O\u2019Neill, J. (2015). Antimicrobials in Agriculture and the Environment: Reducing Unnecessary Use and Waste the Review on Antimicrobial Resistance, Review on Antimicrobial Resistance."},{"key":"ref_2","unstructured":"WHO (2000). WHO Global Principles for the Containment of Antimicrobial Resistance in Animals Intended for Food, World Health Organization."},{"key":"ref_3","unstructured":"WHO (2005). Critically Important Antibacterial Agents for Human Medicine for Risk Management Strategies of Non-Human Use: Report of a WHO Working Group Consultation, World Health Organization."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"e316","DOI":"10.1016\/S2542-5196(17)30141-9","article-title":"Restricting the Use of Antibiotics in Food-Producing Animals and Its Associations with Antibiotic Resistance in Food-Producing Animals and Human Beings: A Systematic Review and Meta-Analysis","volume":"1","author":"Tang","year":"2017","journal-title":"Lancet Planet. Health"},{"key":"ref_5","first-page":"e000822","article-title":"European Regulations on Prevention Use of Antimicrobials from January 2022","volume":"44","author":"Simjee","year":"2022","journal-title":"Rev. Bras. Med. Vet."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"4965","DOI":"10.3168\/jds.2012-5713","article-title":"Herd-Level Relationship between Antimicrobial Use and Presence or Absence of Antimicrobial Resistance in Gram-Negative Bovine Mastitis Pathogens on Canadian Dairy Farms","volume":"96","author":"Saini","year":"2013","journal-title":"J. Dairy Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"104937","DOI":"10.1016\/j.prevetmed.2020.104937","article-title":"Antimicrobial Use for Treatment of Clinical Mastitis in Dairy Herds from Brazil and Its Association with Herd-Level Descriptors","volume":"176","author":"Tomazi","year":"2020","journal-title":"Prev. Vet. Med."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3761","DOI":"10.3168\/jds.2022-22826","article-title":"Invited Review: Selective Treatment of Clinical Mastitis in Dairy Cattle","volume":"106","author":"McCubbin","year":"2023","journal-title":"J. Dairy Sci."},{"key":"ref_9","unstructured":"Food and Agriculture Organization (FAO), World Organization for Animal Health (OIE), and World Health Organization (WHO). (2003). FAO OIE WHO Joint FAO\/OIE\/WHO Expert Workshop on Non-Human Antimicrobial Usage and Antimicrobial Resistance: Scientific Assessment, World Health Organization."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"4441","DOI":"10.3168\/jds.2010-4046","article-title":"The Selective Treatment of Clinical Mastitis Based on On-Farm Culture Results: I. Effects on Antibiotic Use, Milk Withholding Time, and Short-Term Clinical and Bacteriological Outcomes","volume":"94","author":"Lago","year":"2011","journal-title":"J. Dairy Sci."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"389","DOI":"10.1016\/j.cvfa.2018.06.001","article-title":"Use of Rapid Culture Systems to Guide Clinical Mastitis Treatment Decisions","volume":"34","author":"Lago","year":"2018","journal-title":"Vet. Clin. N. Am.\u2014Food Anim. Pract."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"9115","DOI":"10.3168\/jds.2020-19513","article-title":"Evaluation of Chromogenic Culture Media for Rapid Identification of Microorganisms Isolated from Cows with Clinical and Subclinical Mastitis","volume":"104","author":"Granja","year":"2021","journal-title":"J. Dairy Sci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"10585","DOI":"10.3168\/jds.2020-18365","article-title":"Critically Important Antimicrobials Are Generally Not Needed to Treat Nonsevere Clinical Mastitis in Lactating Dairy Cows: Results from a Network Meta-Analysis","volume":"103","author":"Nobrega","year":"2020","journal-title":"J. Dairy Sci."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1461","DOI":"10.2460\/javma.2005.227.1461","article-title":"Relationship between Antimicrobial Susceptibility of Clinical Mastitis Pathogens and Treatment Outcome in Cows","volume":"227","author":"Hoe","year":"2005","journal-title":"J. Am. Vet. Med. Assoc."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2589","DOI":"10.3168\/jds.2008-1693","article-title":"Relationship between in Vitro Susceptibility Test Results and Treatment Outcomes for Gram-Positive Mastitis Pathogens Following Treatment with Cephapirin Sodium","volume":"92","author":"Apparao","year":"2009","journal-title":"J. Dairy Sci."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1437","DOI":"10.2460\/javma.234.11.1437","article-title":"Relationship between Results of in Vitro Susceptibility Tests and Outcomes Following Treatment with Pirlimycin Hydrochloride in Cows with Subclinical Mastitis Associated with Gram-Positive Pathogens","volume":"234","author":"Apparao","year":"2009","journal-title":"J. Am. Vet. Med. Assoc."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"108644","DOI":"10.1016\/j.vetmic.2020.108644","article-title":"Antimicrobial Susceptibility of Nine Udder Pathogens Recovered from Bovine Clinical Mastitis Milk in Europe 2015\u20132016: VetPath Results","volume":"245","author":"Youala","year":"2020","journal-title":"Vet. Microbiol."},{"key":"ref_18","unstructured":"Middleton, J.R., Fox, L.K., Pighetti, G., and Petersson-Wolfe, C. (2017). Laboratory Handbook on Bovine Mastitis, National Mastitis Council. [3rd ed.]."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"3397","DOI":"10.3168\/jds.2010-3925","article-title":"Risk Factors Associated with Short-Term Post-Treatment Outcomes of Clinical Mastitis","volume":"94","author":"Ruegg","year":"2011","journal-title":"J. Dairy Sci."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Freu, G., Tomazi, T., Monteiro, C.P., Barcelos, M.M., Alves, B.G., and Dos Santos, M.V. (2020). Internal Teat Sealant Administered at Drying off Reduces Intramammary Infections during the Dry and Early Lactation Periods of Dairy Cows. Animals, 10.","DOI":"10.3390\/ani10091522"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"849","DOI":"10.1007\/s42770-019-00110-5","article-title":"Comparison of Standard and On-Plate Extraction Protocols for Identification of Mastitis-Causing Bacteria by MALDI-TOF MS","volume":"50","author":"Barcelos","year":"2019","journal-title":"Braz. J. Microbiol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"104489","DOI":"10.1016\/j.micpath.2020.104489","article-title":"Differentiation of Non-Aureus Staphylococci Species Isolated from Bovine Mastitis by PCR-RFLP of GroEL and Gap Genes in Comparison to MALDI-TOF Mass Spectrometry","volume":"149","author":"Conesa","year":"2020","journal-title":"Microb. Pathog."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"3813","DOI":"10.3168\/jds.2023-24086","article-title":"Frequency of Non-Aureus Staphylococci and Mammaliicocci Species Isolated from Quarter Clinical Mastitis: A 6-Year Retrospective Study","volume":"107","author":"Freu","year":"2024","journal-title":"J. Dairy Sci."},{"key":"ref_24","unstructured":"CLSI (2025). CLSI VET01S TM Performance Standards for Antimicrobial Disk, CLSI. [7th ed.]."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"12030","DOI":"10.3168\/jds.2021-20177","article-title":"Association between Antimicrobial Use and Antimicrobial Resistance of Streptococcus Uberis Causing Clinical Mastitis","volume":"104","author":"Martins","year":"2021","journal-title":"J. Dairy Sci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"e20240555","DOI":"10.1590\/0103-8478cr20240555","article-title":"Antimicrobials in the Management of Bovine Mastitis","volume":"55","author":"Piaia","year":"2025","journal-title":"Ci\u00eancia Rural"},{"key":"ref_27","unstructured":"CLSI (2024). CLSI M100TM, Performance Standards for Antimicrobial Susceptibility Testing, Clinical and Laboratory Standards Institute. [33rd ed.]. CLSI supplement M100."},{"key":"ref_28","unstructured":"European Committee on Antimicrobial Susceptibility Testing EUCAST (2025, November 05). Breakpoint-Tabelle 15.0. Available online: https:\/\/www.eucast.org."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"2177","DOI":"10.1128\/JCM.00418-14","article-title":"In Vitro Antimicrobial Susceptibility of Aerococcus Urinae","volume":"52","author":"Humphries","year":"2014","journal-title":"J. Clin. Microbiol."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Kolar, Q.K., Goncalves, J.L., Erskine, R.J., and Ruegg, P.L. (2024). Comparison of Minimum Inhibitory Concentrations of Selected Antimicrobials for Non-Aureus Staphylococci, Enterococci, Lactococci, and Streptococci Isolated from Milk Samples of Cows with Clinical Mastitis. Antibiotics, 13.","DOI":"10.3390\/antibiotics13010091"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1","DOI":"10.18637\/jss.v067.i01","article-title":"Fitting Linear Mixed-Effects Models Using Lme4","volume":"67","author":"Bates","year":"2015","journal-title":"J. Stat. Softw."},{"key":"ref_32","first-page":"1","article-title":"Pandas: A Foundational Python Library for Data Analysis and Statistics","volume":"14","author":"McKinney","year":"2011","journal-title":"Python High Perform. Sci. Comput."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Seabold, S., and Perktold, J. (2010). Statsmodels: Econometric and Statistical Modeling with Python. Proceedings of the 9th Python in Science Conference, SciPy.","DOI":"10.25080\/Majora-92bf1922-011"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"268","DOI":"10.1111\/j.1469-0691.2011.03570.x","article-title":"Multidrug-Resistant, Extensively Drug-Resistant and Pandrug-Resistant Bacteria: An International Expert Proposal for Interim Standard Definitions for Acquired Resistance","volume":"18","author":"Magiorakos","year":"2012","journal-title":"Clin. Microbiol. Infect."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1111\/jvp.12057","article-title":"Treatment for Bovine Escherichia Coli Mastitis\u2014An Evidence-Based Approach","volume":"36","author":"Suojala","year":"2013","journal-title":"J. Vet. Pharmacol. Ther."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"3322","DOI":"10.3168\/jds.S0022-0302(04)73468-2","article-title":"Extended Ceftiofur Therapy for Treatment of Experimentally-Induced Streptococcus Uberis Mastitis in Lactating Dairy Cattle","volume":"87","author":"Oliver","year":"2004","journal-title":"J. Dairy Sci."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1080\/00480169.2007.36762","article-title":"Clinical and Bacteriological Response to Treatment of Clinical Mastitis with One of Three Intramammary Antibiotics","volume":"55","author":"McDougall","year":"2007","journal-title":"N. Z. Vet. J."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"3364","DOI":"10.3168\/jds.2020-18830","article-title":"Negatively Controlled, Randomized Clinical Trial Comparing Different Antimicrobial Interventions for Treatment of Clinical Mastitis Caused by Gram-Positive Pathogens","volume":"104","author":"Tomazi","year":"2021","journal-title":"J. Dairy Sci."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"5696","DOI":"10.3168\/jds.2022-22993","article-title":"Treatment of Mild to Moderate Clinical Bovine Mastitis Caused by Gram-Positive Bacteria: A Noninferiority Randomized Trial of Local Penicillin Treatment Alone or Combined with Systemic Treatment","volume":"106","author":"Svennesen","year":"2023","journal-title":"J. Dairy Sci."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"413","DOI":"10.1016\/j.cvfa.2018.06.002","article-title":"Making Antibiotic Treatment Decisions for Clinical Mastitis","volume":"34","author":"Ruegg","year":"2018","journal-title":"Vet. Clin. N. Am.\u2014Food Anim. Pract."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"4727","DOI":"10.3168\/jds.2018-15272","article-title":"Symposium Review: Features of Staphylococcus Aureus Mastitis Pathogenesis That Guide Vaccine Development Strategies","volume":"102","author":"Malouin","year":"2019","journal-title":"J. Dairy Sci."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Fidelis, C.E., Orsi, A.M., Freu, G., Gon\u00e7alves, J.L., and dos Santos, M.V. (2024). Biofilm Formation and Antimicrobial Resistance of Staphylococcus Aureus and Streptococcus Uberis Isolates from Bovine Mastitis. Vet. Sci., 11.","DOI":"10.3390\/vetsci11040170"},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"De Buck, J., Ha, V., Naushad, S., Nobrega, D.B., Luby, C., Middleton, J.R., De Vliegher, S., and Barkema, H.W. (2021). Non-Aureus Staphylococci and Bovine Udder Health: Current Understanding and Knowledge Gaps. Front. Vet. Sci., 8.","DOI":"10.3389\/fvets.2021.658031"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"105482","DOI":"10.1016\/j.rvsc.2024.105482","article-title":"Staphylococcus Aureus and Methicillin-Resistant Staphylococci and Mammaliicocci in the Bulk Tank Milk of Dairy Cows from a Livestock-Dense Area in Northern Italy","volume":"182","author":"Locatelli","year":"2025","journal-title":"Res. Vet. Sci."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"6594","DOI":"10.3168\/jds.2014-8027","article-title":"In Vitro Susceptibility of Bovine Mastitis Pathogens to a Combination of Penicillin and Framycetin: Development of Interpretive Criteria for Testing by Broth Microdilution and Disk Diffusion","volume":"97","author":"Pillar","year":"2014","journal-title":"J. Dairy Sci."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1016\/j.vetmic.2017.11.021","article-title":"Monitoring of Antimicrobial Susceptibility of Udder Pathogens Recovered from Cases of Clinical Mastitis in Dairy Cows across Europe: VetPath Results","volume":"213","author":"Simjee","year":"2018","journal-title":"Vet. Microbiol."}],"container-title":["Veterinary Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2306-7381\/13\/7\/667\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T10:45:04Z","timestamp":1783593904000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2306-7381\/13\/7\/667"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,9]]},"references-count":46,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["vetsci13070667"],"URL":"https:\/\/doi.org\/10.3390\/vetsci13070667","relation":{},"ISSN":["2306-7381"],"issn-type":[{"value":"2306-7381","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,9]]}}}