DAIRY Australia confirmed this week the bacteria that cause mastitis are still susceptible to current antibiotics used by producers in South Eastern Australia, according to a new pathogen study.
Commenting on the outcome of the ‘Survey of Mastitis Pathogens in the South Eastern Australian Dairy
Industry’ released recently, Dairy Australia echoed the study’s conclusions that antibiotics used in dairy
cattle mastitis therapy in South Eastern Australia are as effective as they were 30 years ago.
Conducted by mastitis control experts Dairy Focus, in collaboration with Zoetis, formerly Pfizer Animal
Health, the survey is the most comprehensive of its kind in Australia since the early 1980s.
The stand out result from the research is that minimal resistance has developed to the antimicrobials used to treat mastitis in Australia.
“The results we’ve seen from this survey show that mastitis therapies currently available in Australia continue to be as effective as we’ve understood them to be in past years,” said Dr John Penry, Project Leader for Countdown 2020, Dairy Australia.
“For producers, this means that they can continue to rely on antibiotics with the understanding that the most common pathogens causing clinical mastitis cases remain susceptible to the range of antibiotics available based on laboratory assessment.”
The survey also explored the most common pathogens present in clinical and subclinical mastitis cases
across all four key dairy cattle farming regions in South Eastern Australia.
Across all regions, Streptococcus uberis was identified as the most common clinical mastitis pathogen with a presence in more than 54 per cent of all culture positive samples taken as part of the survey.
The study also found that together Streptococcus uberis, Staphylococcus aureus, Escherichia coli and
Streptococcus dysgalactiae accounted for nearly 90 per cent of clinical mastitis cases in south eastern
Australia.
In subclinical cases of mastitis Staphylococcus aureus was the most commonly occurring of the four endemic pathogens (17.5 per cent).
Streptococcus uberis (13.1 per cent) was the next most common.
Comparing the distribution of these pathogens across key dairy cattle regions in South Eastern Australia was also a key part of the research.
The survey found that the prevalence of the four major clinical mastitis pathogens (Streptococcus uberis, Staphylococcus aureus, Escherichia coli and Streptococcus dysgalactiae) was similar across the Gippsland, Northern Victoria, Tasmanian and Western Victoria regions.
While season, stage of lactation and a cow’s age may impact the clinical mastitis incidence rates on farm,
the results of the survey showed that the prevalence of major pathogens does not alter significantly with
these factors.
Additionally, Streptococcus uberis was identified as the dominant pathogen at all stages of lactation consistently isolated at a rate greater than 30 per cent of positive culture samples.
