Dairy cows: sanitising of Staphylococcus aureus genotype B-positive herds

Mastitis is the most common disease of cows, and also leads to very high costs in the Swiss dairy industry. A significant percentage of cases can be traced back to the Staphylococcus aureus genotype B (GTB) pathogen. Unlike all other Staphylococcus aureus genotypes, this one is infectious, and thus leads to problems in herds, particularly in alpine regions. Moreover, under certain circumstances Staphylococcus aureus GTB also produces enterotoxins which cause food poisoning in humans. Cheese containing enterotoxins must be incinerated, which has led time and again to very high losses in the alpine farming sector. In order to stamp out Staphylococcus aureus GTB at herd level, Agroscope has developed a highly specific and sensitive qPCR test for detecting this pathogen in milk, as well as a highly efficient and reliable process for sanitising infected herds. The only process of its kind in the world using a genotype-specific qPCR assay, this method represents a breakthrough in the control of Staphylococcus aureus as a pathogen of infectious mastitis. In one study, they actually succeeded in completely and sustainably sanitising all GTB-infected herds within nine months, with 93 % of all GTB-positive cows being successfully cured and milk cell counts falling significantly. The procedure was implemented with great success in the canton of Ticino, which has a significant GTB problem. Thanks to the sanitisation project, the rate of infection of the cows in this canton fell from 10 % to 0,3 %. The sanitised herds remained GTB-free after the treatment. Successful GTB sanitisation is based on strict implementation of the five basic pillars: 1. A highly sensitive, highly GTB-specific qPCR test; 2. Strict application of the compulsory farmyard measures, such as milking by group and thorough cleaning of the milking plant twice daily; 3. Monthly testing of the milk of the individual cows with the qPCR assay and adjustment of the milking groups; 4. Selection of the antibiotic for the treatment of GTB-positive cows on the basis of whole-genome analyses; 5. Treatment and veterinary influence.

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