THE IMPORTANCE OF STAPHYLOCOCCUS AUREUS IN SA DAIRY HERDS.

Staphylococcus aureus is internationally recognised as the most important pathogen of intra-udder infection and the foremost reason for economic loss to dairy farmers. South Africa is not different, but the spread and antimicrobial resistance (AMR) of different strains compared to elsewhere in the world is not well documented, which then was the main focus of the review by the authors cited.

Results for major countries in Europe, North America, China and Africa (including South Africa) showed that S. aureus between 1975 and 2018 was probably the most prevalent cause of mastitis with estimates ranging from 7 to 40% of all cows infected. From a study undertaken between 1996 and 2009 involving 379 000 lactating and 11 950 dry cows in South Africa, it was revealed that non-aureus staphylococcus were by far the most abundant bacteria isolated (>60%), followed by S. aureus (>17%) and αβ haemolytic S. aureus (about 8%), but the prevalence is different in different regions of the country. In terms of AMR, there are similarities but also great variation in antibiotic resistance of S. aureus between different regions of Southern Africa and other countries. A difference was also found between maltose-positive and the emerging maltose-negative S. aureus pathogen and between different levels of management.

As there is only a small selection of intra-udder antibiotics available in South Africa, which are mainly products based on ampicillin and cloxacillin, and AMR patterns caused by S. aureus vary between regions and between maltose-positive and maltose-negative strains, specific surveillance data as defined by climate, region and even farm are important, in order to reduce the incidence of unnecessary or incorrect treatment of antibiotics. This research should be ongoing.