Staphylococcus mastitis, biofilms, and antibiotic resistance: Barriers to milk quality and food safety on artisanal and farmstead cheese producing farms in Vermont

Project Overview

Project Type: Graduate Student
Funds awarded in 2014: $14,999.00
Projected End Date: 12/31/2016
Grant Recipient: University of Vermont
Region: Northeast
State: Vermont
Graduate Student:
Faculty Advisor:
John Barlow
University of Vermont

Annual Reports

Information Products


  • Animal Products: dairy


  • Animal Production: animal protection and health
  • Education and Training: extension

    Proposal abstract:

    The objective of this project is to support farmstead cheese producers with improved knowledge on mastitis, milk quality and food safety. Mastitis is the most important cause of production losses on dairy farms, and farmstead cheese producers are unique because their value added on-farm production requires an integrated approach to animal health, milk quality and food safety. This project will address the emerging problem of mastitis caused by the coagulase negative staphylococci (CNS). CNS species are the most common cause of mastitis and may contribute to biofilms on milking equipment and cheese production facilities. They are also a possible reservoir of antimicrobial resistance. Yet some CNS species are desirable in cheese making and other CNS species are thought to be beneficial commensals of the udder skin. Understanding Staphylococcus epidemiology and ecology on artisan cheese farms will give more insight to the contributions of specific species in this diverse group. Using molecular techniques, we will quantify the diversity of the CNS species on farms that make artisan cheese. We are interested in factors that allow specific species to persist in particular niches on farms. Our long-term goal is to identify practices that prevent persistence of pathogens while encouraging beneficial microbes. We will generate epidemiologic data, which can be used to help farmers mitigate mastitis pathogen transmission, improve milk quality and food safety, and enhance farm productivity and sustainability. Outreach will include: 1) a scientific publication; 2) technical reports to farmers participating in the project; and 3) presentations at stakeholder meetings.

    Project objectives from proposal:

    1. To identify the sources of Staphylococcus species on farms that make farmstead cheese.
    We will describe the detailed distribution of the CNS species on 5 dairy farms that make artisan or farmstead cheese. Under this objective we will use sequence-based molecular methods to describe the comparative distribution of bacteria isolated from various sources or niches on these farms.
    The specific aims of this objective are to:
    a) Identify the CNS species that are opportunistic mastitis pathogens and determine their sources on these farms.
    b) Identify the CNS species that are normal flora of the udder and teat skin but are not commonly isolated from cases of mastitis, and describe these as a component of the beneficial teat skin commensal bacteria.
    c)Identify the sources of CNS species that are known beneficial bacteria in cheese maturation.
    2. To quantify the association between antibiotic resistance or biofilm formation and the staphylococci species or strains isolated from various sources on dairy farms. Antibiotic resistance threatens both human and animal health and methicillin resistant staphylococci are a particular problem in both community and hospital settings. Antibiotic use in agriculture has been implicated as contributing to this problem, yet little is know about the source and diversity of staphylococci that carry antibiotic resistance genes on dairy farms. Our past research has shown that antibiotic resistant staphylococci are present on both organic and conventional dairy farms, albeit at lower levels on organic farms. Antibiotic resistance can be enhanced by formation of bacterial communities (biofilms). Biofilms are important in the survival of bacteria in various environments including milking and cheese making equipment. Biofilms may also to play a role in mammary gland infections and lead to chronic infections. Little research has been done to describe the prevalence of antibiotic resistant and biofilm forming phenotypes among the diverse CNS species found on dairy farms. Data from this objective will inform mastitis treatment, milk quality and food safety programs for the farmers that make artisan cheese. These descriptive data will also inform future research on emerging pathogens and novel control practices on dairy farms.
    The specific aims of this objective are to:
    a) Quantify the prevalence of antimicrobial resistance among the various CNS species isolated from different sources on artisan cheese farms.
    b) Quantify the prevalence of biofilm forming bacteria among the various CNS species isolated from different sources on artisan cheese farms.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.