Changes in antimicrobial resistance of Staphylococcus aureus in bovine quarter milk samples from southern Germany between 2012 and 2022.

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  • Additional Information
    • Source:
      Publisher: American Dairy Science Association Country of Publication: United States NLM ID: 2985126R Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1525-3198 (Electronic) Linking ISSN: 00220302 NLM ISO Abbreviation: J Dairy Sci Subsets: MEDLINE
    • Publication Information:
      Publication: Champaign, IL : American Dairy Science Association
      Original Publication: Lancaster, Pa. [etc.]
    • Subject Terms:
      Milk*/microbiology ; Staphylococcus aureus*/drug effects ; Microbial Sensitivity Tests* ; Anti-Bacterial Agents*/pharmacology; Animals ; Cattle ; Germany ; Female ; Staphylococcal Infections/veterinary ; Staphylococcal Infections/microbiology ; Mastitis, Bovine/microbiology
    • Abstract:
      The objective of this study was to describe the in vitro resistance of Staphylococcus aureus from bovine quarter milk samples obtained by the udder health laboratory of the Bavarian Animal Health Services between 2012 and 2022. All S. aureus samples were tested for β-lactamase production and only forwarded to further microbroth susceptibility testing either if the β-lactamase result was positive or upon explicit request by the submitter. The growth of most S. aureus isolates was inhibited at the lowest evaluated minimum inhibitory concentration (MIC) of tested antimicrobials, with the MIC 50 and MIC 90 (the MIC where 50% and 90% of isolates were inhibited by the tested antibiotics, respectively) mostly beneath the respective breakpoint. On average, about one-fourth (24%, n = 5,718) of tested isolates was resistant to erythromycin. However, the prevalence of resistant isolates dropped from 53% (n = 1,018) in 2012 to 8% (n = 113) in 2022. The second highest prevalence of in vitro resistance was to penicillin (17%, of all isolates tested for β-lactamase production, n = 28,069). Less than 14% of isolates were resistant to the remaining assessed antimicrobial agents (cefoperazone, pirlimycin, kanamycin-cefalexin, marbofloxacin, amoxicillin-clavulanate, cefquinome, or cefazolin, respectively). Over the years, 4% (n = 959) of the S. aureus isolates selected for microbroth susceptibility testing (and 0.8% (n = 1,392) of all submitted S. aureus isolates) were methicillin-resistant S. aureus, and 5% (n = 1,162) of S. aureus isolates were multidrug resistant. However, there was an overall trend toward fewer resistant isolates. These findings are consistent with those of several European monitoring programs that reported a slight decrease of antimicrobial resistance (AMR) of bovine S. aureus in countries where antibiotic use in veterinary medicine was reduced. Notably, isolates of clinical mastitis cases were consistently less likely to express in vitro resistance than isolates obtained from milk of healthy cows or subclinical mastitis cases. In conclusion, AMR of S. aureus was decreasing and penicillin should remain the first-choice antimicrobial in the attempt of treating S. aureus intramammary infections in Bavaria.
      (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)
    • Contributed Indexing:
      Keywords: Staphylococcus aureus; antimicrobial resistance; dairy cattle; mastitis
    • Accession Number:
      0 (Anti-Bacterial Agents)
    • Publication Date:
      Date Created: 20231117 Date Completed: 20240522 Latest Revision: 20240522
    • Publication Date:
      20240523
    • Accession Number:
      10.3168/jds.2023-23997
    • Accession Number:
      37977447