1. University of Copenhagen
Faculty of Health and Medical Sciences
Department of Veterinary and Animal Sciences
Staphylococcus aureus and Streptococcus agalactiae in Milk and Teat Skin from Cows in Automatic Milking Systems
Line Svennesen1, Yasser Mahmmod1, Karl Pedersen2, Volker Krömker3, and Ilka C. Klaas1,4
1University of Copenhagen, Copenhagen, Denmark 2National Veterinary Institute, Technical University of Denmark, Kgs. Lyngby, Denmark 3University of Applied Sciences and Arts, Hannover, Germany 4DeLaval International AB, Tumba, Sweden (present)
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Aim of Study
The aim of this study was to investigate the association between teat skin colonization and intramammary infections with S. aureus or S. agalactiae in herds with automatic milking systems (AMS).
Summary
Knowledge of pathogenic reservoirs is crucial for controlling the transmission of contagious mastitis pathogens like Staphylococcus aureus and Streptococcus agalactiae. The role of the teat skin as a reservoir of S. agalactiae is unknown, and still discussed for S. aureus. Furthermore, teat skin colonization is not yet investigated in automatic milking systems. The aim of this study was to investigate the association between teat skin colonization and intramammary infections with S. aureus or S. agalactiae in herds with automatic milking systems. Our results indicate associations between teat skin colonization and intramammary infections for both S. aureus and S. agalactiae, and further statistical analysis will be carried out. To our knowledge this is the first time S. agalactiae is isolated from teat skin, however, only from cows with S. agalactiae intramammary infections.
Materials and Methods
Herds:
≥ 3 milking robots
Positive status for S. agalactiae in bulk tank milk (PCR)
8 farmers were interested in participating
Cows:
30-40 cows per herd
≥ 200,000 cells/mL at last milk recording
Not treated with antibiotics 4 weeks prior to sampling
Randomly selected
Quarters:
All milking quarters from selected cows
Teat skin samples:
Teats cleaned with dry paper towel
Modified wet-dry method ; wet rayon swab followed by dry degrees rotation - immersed into 2 ml ¼ Ringer’s solution
Milk samples:
Aseptically collected quarter foremilk samples
Bacteriological culture:
Within 24 hours
10 µL of milk streaked onto a quarter of a plate or 100 µL of teat skin sample inoculated to a whole plate of:
Calf blood agar
Modified Edward’s medium for S. agalactiae
Selective medium for S. aureus
Incubated aerobically at 37°C for 48 hours
Identification based on morphology
Identification verified using MALDI-TOF or Latex agglutination test
Results
Milk and teat skin samples cultured from 1142 quarters (300 cows)
Quarters were considered positive if ≥ 1 colony of S. aureus or S. agalactiae on at least one of the three media used
S. agalactiae:
7.4 % of milk samples positive (n = 84 quarters)
0.35 % of teat skin samples positive (n = 4)
Quarters positive both teat skin and milk = 0.26 % (n = 3)
Teat skin positive quarters only from cows with S. agalactiae isolated from the same or another quarter
S. aureus:
8.1 % of milk samples positive (n = 93)
6.6 % of teat skin samples positive (n = 75)
Quarters positive both teat skin and milk = 1.3 % (n = 15)
For S. aureus there were 3.2 higher odds of a quarter being milk positive and teat skin positive, relative to being teat skin negative and milk positive (P = ).
Take Home Message
S. agalactiae can be isolated from the teat skin of cows with S. agalactiae in milk (in herds with AMS), however it appears to be very uncommon even in high-risk cows with high somatic cell count from herds with S. agalactiae history.
For S. aureus, there is considerable evidence of interrelation between teat skin colonization and intramammary infection.
This research study was funded by The Danish Milk Levy Fund