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Is Staph Aureus Lurking in Your Herd? Five Proven Strategies to Stop It

Why is Staph. aureus so challenging?
Staphylococcus aureus (Staph. aureus) is one of the most frustrating pathogens in dairy farming. Unlike many mastitis-causing bacteria, Staph. aureus can evade the cow’s immune system by living inside udder tissue cells, making it difficult to fully eliminate with antibiotic treatment. It often causes subclinical infections, where despite an elevated somatic cell count (SCC) the cow displays no visible signs of illness. As well as impacted SCC counts, subclinical infections caused by Staph. aureus lead to reduced milk yields, and can have a negative impact on milk composition, which will ultimately impact your profitability. If infected animals going unnoticed and untreated, Staph. aureus can silently pass from cow to cows through the herd causing a major herd health problem. Once there is a Staph aureus problem in the herd, its ability to form protective biofilms and develop antibiotic resistance makes Staph. aureus extremely difficult to eradicate.

Here are five practical ways to reduce its impact on your farm:

1. Implement good hygiene and sanitation practices
Good hygiene is the frontline defence against the spread of Staph. aureus. Regular cleaning and disinfecting of milking equipment, gloves, and cow teats helps prevent cow-to-cow transmission. Focus on consistent teat spraying, and avoid over-milking which can cause the teat-end damage that gives bacteria an easy entry point. Any cow that has been identified has having Staph. aureus should be milked separately from the rest of the herd, or milked last, followed by thorough cleaning the milking equipment used

2. Use vaccines
Vaccination can be an important tool to reduce the severity and incidence of Staph. aureus mastitis. Though vaccines do not prevent infection entirely, they can reduce bacterial load, lower somatic cell counts, and improve treatment outcomes. Work with your veterinarian to identify if a vaccine is suitable for your herd and to develop a vaccination schedule that supports your overall mastitis control strategy.

3. Use on-farm milk culturing to identify, quarantine and treat Staph. Aureus affected cows

Experts now recommend culturing every case of clinical mastitis to identify the bacteria causing it. In addition, regular milk culturing of cows with elevated SCC counts (>150,000 or 200,000 cells/mL is a general guide) enables identification of the silent carriers in the herd. On-farm culturing, using an easy-to-use technology such as Mastatest, means that testing can be carried out efficiently and quickly.

Where Staph. aureus is identified, the cow should be quarantined for treatment. Follow the advice of your veterinarian on the appropriate choice of antibiotic. Staph. aureus strains can be resistant to some antibiotics, so cure might not be achieved with the first agent used.

4. Targeted antibiotic selection

Staph. aureus strains can be resistant to common antibiotics, making it difficult to treat effectively. Your veterinarian can guide you on the appropriate choice of antibiotic that is most likely to achieve a cure. Your veterinarian may recommend antibiotic sensitivity testing in order to make the best selection.

When you use Mastatest to do you on-farm mastitis culturing, you’ll receive information on antibiotic sensitivity of that specific strain at the same time as you receive the bacterial identification. This means you can pick the right antibiotic first time, with no further delay in treatment commencing.

5. Monitor cattle health and inform cull decisions through on-farm milk culturing
Some cows become chronic carriers of Staph. aureus, repeatedly flaring up and acting as a source of infection for others. Regular monitoring of somatic cell counts and milk culturing can help identify these cows. Persistently infected animals that do not respond to treatment should be considered for culling, especially if they pose a risk to the broader herd. Using milk culture data to guide culling decisions allows for a more strategic, evidence-based approach to herd health management.

In summary, controlling Staph. aureus requires a multifaceted approach. By improving hygiene, using vaccines strategically, culturing milk to guide treatment, carefully selecting your antibiotics, and culling chronic cases, farmers can reduce its impact and protect the long-term productivity of their herds.