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Updated: Aug 15, 2026
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
MRSA in bulk tank milk of dairy herds in Germany - changes over time
Bernd-Alois Tenhagen1, Katja Alt1, Mirjam Grobbel1
1Abteilung Biologische Sicherheit, Bundesinstitut für Risikobewertung, Berlin, Germany.
Objective:
Methicillin-resistant Staphylococcus aureus (MRSA) have repeatedly been isolated from dairy herds. It was the purpose of this study to compare the results of 3 subsequent national scale cross-sectional investigations in dairy herds in Germany on the prevalence of MRSA in bulk tank milk and the characteristics of the isolates.
Material And Methods:
The investigations were carried out in 2010, 2014 and 2019, respectively. MRSA were isolated from 25 ml of bulk tank milk using a double selective enrichment protocol. Samples were distributed across the country according to the regional dairy cattle population.
Results:
The prevalence of MRSA in bulk tank milk samples was lower in 2010 than in 2014 and tended to decrease until 2019. Prevalence was higher in samples from conventional than from organic herds and increased with herd size. Most isolates (75/78) were assigned to the clonal complex 398 and the spa-types t011 and t034. Resistance of the isolates to other antimicrobials than beta-lactams decreased over time.
Conclusions:
MRSA remain present in the German dairy population and are found more frequently in larger vs. smaller herds and in conventional vs. organic herds.
Clinical Relevance:
MRSA should be considered in biosecurity protocols and with respect to occupational health of farm staff. Presence of MRSA in raw milk supports the recommendation not to drink unpasteurized raw milk.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) persists in German dairy herds, with prevalence higher in larger, conventional farms. Antimicrobial resistance decreased over time, but MRSA presence in raw milk warrants caution.
Area of Science:
- Veterinary Microbiology
- Food Safety
- Antimicrobial Resistance
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant concern in livestock, including dairy herds.
- Previous studies have indicated the presence of MRSA in German dairy cattle.
Purpose of the Study:
- To compare the prevalence and characteristics of MRSA in German dairy herds across three national cross-sectional surveys.
- To analyze trends in MRSA prevalence and antimicrobial resistance over time.
Main Methods:
- Three national cross-sectional investigations were conducted in 2010, 2014, and 2019.
- MRSA was detected in bulk tank milk using a double selective enrichment protocol.
- Sample distribution reflected regional dairy cattle populations.
Main Results:
- MRSA prevalence in bulk tank milk showed a decrease from 2010 to 2019.
- Prevalence was higher in conventional versus organic herds and increased with herd size.
- Most isolates belonged to clonal complex 398, with decreasing resistance to non-beta-lactam antimicrobials over time.
Conclusions:
- MRSA remains prevalent in German dairy herds, particularly in larger and conventional operations.
- Findings emphasize the need for MRSA in biosecurity and occupational health strategies.
- The presence of MRSA in raw milk reinforces recommendations against consuming unpasteurized milk.
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