Prevalence of Variant GTR<sup>I</sup><i>Staphylococcus aureus</i> Isolated from Dairy Cow Milk Samples in the Alpine Grazing System of the Aosta Valley and Its Association with AMR and Virulence Profiles
<b>Background/Objectives</b>: In the Aosta Valley, the alpine grazing system integrates livestock production and land management. Valdostana breeding has adapted to this mountainous region, but the spread of <i>Staphylococcus aureus</i> within pastures may impact animal healt...
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2025-03-01
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| author | Valentina Monistero Delower Hossain Sara Fusar Poli Elizabeth Sampaio de Medeiros Paola Cremonesi Bianca Castiglioni Filippo Biscarini Hans Ulrich Graber Giulia Mochettaz Sandra Ganio Alessandra Gazzola Maria Filippa Addis Claudio Roullet Antonio Barberio Silvia Deotto Lara Biasio Fernando Ulloa Davide Galanti Valerio Bronzo Paolo Moroni |
| author_facet | Valentina Monistero Delower Hossain Sara Fusar Poli Elizabeth Sampaio de Medeiros Paola Cremonesi Bianca Castiglioni Filippo Biscarini Hans Ulrich Graber Giulia Mochettaz Sandra Ganio Alessandra Gazzola Maria Filippa Addis Claudio Roullet Antonio Barberio Silvia Deotto Lara Biasio Fernando Ulloa Davide Galanti Valerio Bronzo Paolo Moroni |
| author_sort | Valentina Monistero |
| collection | DOAJ |
| description | <b>Background/Objectives</b>: In the Aosta Valley, the alpine grazing system integrates livestock production and land management. Valdostana breeding has adapted to this mountainous region, but the spread of <i>Staphylococcus aureus</i> within pastures may impact animal health. The aim of this study was to provide an overview of <i>S. aureus</i> genotypes associated with antimicrobial resistance (AMR) and virulence profiles in four dairy herds in the Aosta Valley from July 2022 to August 2023. <b>Methods</b>: A total of 468 composite milk samples were collected at three timepoints: T1 (pasture-livestock system), T2 (farm-livestock system), and T3 (pasture-livestock system). <i>S. aureus</i> isolates were characterized by antimicrobial susceptibility testing, ribosomal spacer (RS)-PCR, multilocus sequence typing (MLST), PCR analysis for 28 virulence genes and 6 AMR genes, and <i>adlb</i>-targeted real-time PCR. <b>Results</b>: RS-PCR analysis of 82 <i>S. aureus</i> strains revealed 12 genotypes (GT) in eight clusters (CL). The most prevalent variant was GTR<sup>I</sup> (61%), followed by GTB (15%). Resistance to penicillin was high (69%), with CLR strains showing 88% resistance, and 51% resistance to amoxicillin plus clavulanate. All strains were susceptible to cephalosporins and oxacillin. Macrolide resistance was low (4%), and multi-drug resistance was 6%. AMR gene presence corresponded with susceptibility, with <i>blaZ</i> detected in 94% of CLR strains. CLR strains also possessed genes for biofilm formation and virulence factors. <b>Conclusions</b>: This study highlights the presence of AMR and virulence factors in <i>S. aureus</i> strains from alpine grazing systems, underscoring the need for ongoing monitoring to mitigate risks to animal health. |
| format | Article |
| id | doaj-art-e0167d1f9f84466484dc5a8e3e4a62aa |
| institution | DOAJ |
| issn | 2079-6382 |
| language | English |
| publishDate | 2025-03-01 |
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| spelling | doaj-art-e0167d1f9f84466484dc5a8e3e4a62aa2025-08-20T03:14:17ZengMDPI AGAntibiotics2079-63822025-03-0114434810.3390/antibiotics14040348Prevalence of Variant GTR<sup>I</sup><i>Staphylococcus aureus</i> Isolated from Dairy Cow Milk Samples in the Alpine Grazing System of the Aosta Valley and Its Association with AMR and Virulence ProfilesValentina Monistero0Delower Hossain1Sara Fusar Poli2Elizabeth Sampaio de Medeiros3Paola Cremonesi4Bianca Castiglioni5Filippo Biscarini6Hans Ulrich Graber7Giulia Mochettaz8Sandra Ganio9Alessandra Gazzola10Maria Filippa Addis11Claudio Roullet12Antonio Barberio13Silvia Deotto14Lara Biasio15Fernando Ulloa16Davide Galanti17Valerio Bronzo18Paolo Moroni19Dipartimento di Medicina Veterinaria e Scienze Animali, Università Degli Studi di Milano, 26900 Lodi, ItalyDipartimento di Medicina Veterinaria e Scienze Animali, Università Degli Studi di Milano, 26900 Lodi, ItalyDipartimento di Medicina Veterinaria e Scienze Animali, Università Degli Studi di Milano, 26900 Lodi, ItalyDipartimento di Medicina Veterinaria e Scienze Animali, Università Degli Studi di Milano, 26900 Lodi, ItalyInstitute of Agricultural Biology and Biotechnology, National Research Council, 26900 Lodi, ItalyInstitute of Agricultural Biology and Biotechnology, National Research Council, 26900 Lodi, ItalyInstitute of Agricultural Biology and Biotechnology, National Research Council, 26900 Lodi, ItalyFood Microbial Systems, Microbiological Safety of Foods of Animal Origin Group, Agroscope, 3003 Bern, SwitzerlandDipartimento di Prevenzione AUSL Della Valle d’Aosta, 11100 Aosta, ItalyDipartimento di Prevenzione AUSL Della Valle d’Aosta, 11100 Aosta, ItalyIstituto Zooprofilattico Sperimentale Della Lombardia e Dell’emilia-Romagna, 26900 Lodi, ItalyDipartimento di Medicina Veterinaria e Scienze Animali, Università Degli Studi di Milano, 26900 Lodi, ItalyDipartimento di Prevenzione AUSL Della Valle d’Aosta, 11100 Aosta, ItalyIstituto Zooprofilattico Sperimentale Delle Venezie, 35020 Legnaro, ItalyIstituto Zooprofilattico Sperimentale Delle Venezie, 35020 Legnaro, ItalyIstituto Zooprofilattico Sperimentale Delle Venezie, 35020 Legnaro, ItalyEscuela de Graduados, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia 5090000, ChileDipartimento di Medicina Veterinaria e Scienze Animali, Università Degli Studi di Milano, 26900 Lodi, ItalyDipartimento di Medicina Veterinaria e Scienze Animali, Università Degli Studi di Milano, 26900 Lodi, ItalyDipartimento di Medicina Veterinaria e Scienze Animali, Università Degli Studi di Milano, 26900 Lodi, Italy<b>Background/Objectives</b>: In the Aosta Valley, the alpine grazing system integrates livestock production and land management. Valdostana breeding has adapted to this mountainous region, but the spread of <i>Staphylococcus aureus</i> within pastures may impact animal health. The aim of this study was to provide an overview of <i>S. aureus</i> genotypes associated with antimicrobial resistance (AMR) and virulence profiles in four dairy herds in the Aosta Valley from July 2022 to August 2023. <b>Methods</b>: A total of 468 composite milk samples were collected at three timepoints: T1 (pasture-livestock system), T2 (farm-livestock system), and T3 (pasture-livestock system). <i>S. aureus</i> isolates were characterized by antimicrobial susceptibility testing, ribosomal spacer (RS)-PCR, multilocus sequence typing (MLST), PCR analysis for 28 virulence genes and 6 AMR genes, and <i>adlb</i>-targeted real-time PCR. <b>Results</b>: RS-PCR analysis of 82 <i>S. aureus</i> strains revealed 12 genotypes (GT) in eight clusters (CL). The most prevalent variant was GTR<sup>I</sup> (61%), followed by GTB (15%). Resistance to penicillin was high (69%), with CLR strains showing 88% resistance, and 51% resistance to amoxicillin plus clavulanate. All strains were susceptible to cephalosporins and oxacillin. Macrolide resistance was low (4%), and multi-drug resistance was 6%. AMR gene presence corresponded with susceptibility, with <i>blaZ</i> detected in 94% of CLR strains. CLR strains also possessed genes for biofilm formation and virulence factors. <b>Conclusions</b>: This study highlights the presence of AMR and virulence factors in <i>S. aureus</i> strains from alpine grazing systems, underscoring the need for ongoing monitoring to mitigate risks to animal health.https://www.mdpi.com/2079-6382/14/4/348alpine grazing system<i>Staphylococcus aureus</i>intramammary infectiongenotypingantimicrobial resistancevirulence genes |
| spellingShingle | Valentina Monistero Delower Hossain Sara Fusar Poli Elizabeth Sampaio de Medeiros Paola Cremonesi Bianca Castiglioni Filippo Biscarini Hans Ulrich Graber Giulia Mochettaz Sandra Ganio Alessandra Gazzola Maria Filippa Addis Claudio Roullet Antonio Barberio Silvia Deotto Lara Biasio Fernando Ulloa Davide Galanti Valerio Bronzo Paolo Moroni Prevalence of Variant GTR<sup>I</sup><i>Staphylococcus aureus</i> Isolated from Dairy Cow Milk Samples in the Alpine Grazing System of the Aosta Valley and Its Association with AMR and Virulence Profiles Antibiotics alpine grazing system <i>Staphylococcus aureus</i> intramammary infection genotyping antimicrobial resistance virulence genes |
| title | Prevalence of Variant GTR<sup>I</sup><i>Staphylococcus aureus</i> Isolated from Dairy Cow Milk Samples in the Alpine Grazing System of the Aosta Valley and Its Association with AMR and Virulence Profiles |
| title_full | Prevalence of Variant GTR<sup>I</sup><i>Staphylococcus aureus</i> Isolated from Dairy Cow Milk Samples in the Alpine Grazing System of the Aosta Valley and Its Association with AMR and Virulence Profiles |
| title_fullStr | Prevalence of Variant GTR<sup>I</sup><i>Staphylococcus aureus</i> Isolated from Dairy Cow Milk Samples in the Alpine Grazing System of the Aosta Valley and Its Association with AMR and Virulence Profiles |
| title_full_unstemmed | Prevalence of Variant GTR<sup>I</sup><i>Staphylococcus aureus</i> Isolated from Dairy Cow Milk Samples in the Alpine Grazing System of the Aosta Valley and Its Association with AMR and Virulence Profiles |
| title_short | Prevalence of Variant GTR<sup>I</sup><i>Staphylococcus aureus</i> Isolated from Dairy Cow Milk Samples in the Alpine Grazing System of the Aosta Valley and Its Association with AMR and Virulence Profiles |
| title_sort | prevalence of variant gtr sup i sup i staphylococcus aureus i isolated from dairy cow milk samples in the alpine grazing system of the aosta valley and its association with amr and virulence profiles |
| topic | alpine grazing system <i>Staphylococcus aureus</i> intramammary infection genotyping antimicrobial resistance virulence genes |
| url | https://www.mdpi.com/2079-6382/14/4/348 |
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