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Identification of linezolid-resistant Enterococcus spp. in calves: findings from Portuguese high-yielding dairy farms

2025-05-27Conference paper Open access
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dc.contributor.authorRibeiro, Alícia
dc.contributor.authorTeixeira, Maria J.
dc.contributor.authorPinho, Luís
dc.contributor.authorCampos, Carla
dc.contributor.authorNovais, Carla
dc.contributor.authorPeixe, Luísa
dc.contributor.authorBrito, Nuno V.
dc.contributor.authorQuinteira, Sandra
dc.contributor.authorMiranda, Carla
dc.contributor.authorFreitas, Ana R.
dc.contributor.authorCampos, Carla
dc.date.accessioned2026-01-14T11:56:10Z
dc.date.available2026-01-14T11:56:10Z
dc.date.issued2025-05-27
dc.description.abstractAntimicrobial resistance (AMR) is a global health threat requiring a One Health approach, asantibiotic-resistant bacteria canspread between animals and humans. Enterococcusspp., particularly E. faecium(Efm) and E. faecalis(Efs),are keyAMR indicators due to their role as gut commensals and their potential as reservoirs of resistance genes.They are also opportunistic pathogensthat can cause severe human infections. Cattle are a recognized reservoir of multidrug-resistant (MDR) Enterococcusspp.,yet remain among the least studied food-producing animals in this context[1,2]. To assess if contemporary faecal samples from main cattle farms in Northern Portugal carry clinically relevant antibiotic-resistant Enterococcusspp. Thirty bovine fecal swab samples were collected from 10 high-yielding farms with Holstein-Friesian dairy cattle in 2 cities during 2023[3]. Sample processing included pre-enrichment (37ºC/18h) without/with antibiotics (ampicillin 16μg/mL, vancomycin 8μg/mL or florfenicol 16μg/mL) followed by plating onto Slanetz–Bartley selective agar, without/with the same antibiotics (37°C/48h). Typical colonies weres aved for identification (MALDI-TOF MS) and antibiotic susceptibility test (disk diffusion;EUCAST/CLSI). Prevalence percentages were calculated on a per-sample basis.All samples contained Enterococcus(n=43) that were identified as Efm(n=18,60%), E. hirae(n=14, 47%), Efs(n=9, 30%), E. casseliflavus and E. durans(n=1 each, 3%); and resistant to erythromycin (44%), tetracycline (39%), chloramphenicol (20%), ampicillin, linezolid, high-level streptomycin (17%each), ciprofloxacin(13%), and high-level gentamicin (7%). MDR isolates (23%) were mostly obtained from calves rather than adults, and only found in Efs(67%) and Efm(50%) species. Linezolid-resistant isolates were only recovered from supplemented media with florfenicol while those resistant to ampicillin were better detected using culture medium with ampicillinor florfenicol. Ampicillin resistance was only detected in Efm while linezolid resistance was identified in both Efmand Efs (all calves, all MDR, 2 farms). Our study shows that dairy cattle carry MDR Enterococcus spp.,including strains resistant to critically important antibiotics in the treatment of human infections (linezolid). These findings underscore the urgent need for sustained AMR surveillance and cross-sector collaboration within a One Health framework.eng
dc.identifier.citationRibeiro, A., Teixeira, M. J., Pinho, L., Campos, C., Novais, C., Peixe, L., Brito, N. V., Quinteira, S., Miranda, C., & Freitas, A. R. (2025). Identification of linezolid-resistant Enterococcus spp. in calves: Findings from Portuguese high-yielding dairy farms. IV 1H-TOXRUN INTERNATIONAL CONGRESS 2025 - Scientific Letters Book of Abstracts, 1(Sup.1). https://doi.org/10.48797/sl.2025.324
dc.identifier.doi10.48797/sl.2025.324
dc.identifier.eissn2795-5117
dc.identifier.urihttp://hdl.handle.net/10400.22/31517
dc.language.isoeng
dc.peerreviewedyes
dc.publisherIUCS-CESPU Publishing
dc.relation.hasversionhttps://publicacoes.cespu.pt/index.php/sl/article/view/324
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/
dc.subjectAntimicrobial resistance
dc.subjectEnterococcus spp.
dc.subjectCattle
dc.titleIdentification of linezolid-resistant Enterococcus spp. in calves: findings from Portuguese high-yielding dairy farmseng
dc.typeconference paper
dspace.entity.typePublication
oaire.citation.conferenceDate2025-05
oaire.citation.conferencePlacePorto
oaire.citation.issueSup1
oaire.citation.titleIV 1H-TOXRUN INTERNATIONAL CONGRESS 2025 - Scientific Letters - Book of Abstracts
oaire.citation.volume1
oaire.versionhttp://purl.org/coar/version/c_970fb48d4fbd8a85
person.familyNameCampos
person.givenNameCarla
person.identifier.ciencia-idA71C-B158-BC1F
person.identifier.orcid0000-0002-6220-4469
relation.isAuthorOfPublication2d983798-af3d-467b-a97e-e5629edf5409
relation.isAuthorOfPublication.latestForDiscovery2d983798-af3d-467b-a97e-e5629edf5409

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