Mastigram+ – the new on-farm Gram positive detection test

Mastigram+ is the new on-farm Gram positive detection test that will change the way mastitis is treated on our farms.

Clinical mastitis is a significant problem on our dairy farms due to its impact on health, welfare and productivity. It is also a major contributor to antibiotic use in dairy cattle. Mastitis is inflammation of the mammary gland and is most frequently caused by bacterial intramammary infection. Mastitis causes physical and chemical changes in the milk which can be detected through a variety of methods. Once detected, there is limited information to help inform treatment decision making of the animal. The bacteria that can cause mastitis can be categorised as either Gram positive or Gram negative. Knowing which type of bacteria has caused the clinical case of mastitis means that an informed decision can be made about the most appropriate antibiotic for treatment. The Vetscan Rapid Mastigram+ test from Zoetis is the first on-farm lateral flow diagnostic test that can identify Gram positive bacteria in the time between milkings. It has very high diagnostic accuracy, with 99.1% sensitivity and 100% specificity. This means producers can be confident whether or not the mastitis case has a Gram positive bacteria present or not.

Samples are taken at the point of detection of a new mild or moderate clinical mastitis case. Only a sample of 1ml is required to run the test. At this time the cow can be treated with a non-steroidal anti-inflammatory medicine (NSAID). The sample is then incubated for 7 hours and then the lateral flow dip test is run. The incubated milk sample is placed in a test tube and the lateral flow stick inserted. After 10 minutes the result can be read from the test strip. This will produce a test result in time for the next milking so that a treatment decision can be made. The presence of a Gram positive bacteria, a positive result, suggests that the case may benefit from treatment with a narrow spectrum target course of antibiotics which can be prescribed by the vet. A negative test result, indicating that a Gram positive bacteria is not present in the sample, may mean that treatment with antibiotics is not required. Many Gram negative bacteria that cause clinical mastitis have a high self cure rate, meaning that antibiotics are not always required.

There are many benefits to knowing whether a Gram positive bacteria is present in the milk sample of a mastitis case. Firstly and fundamentally this facilitates the responsible use of antibiotics, and contributes to the One Health approach to minimising the spread of antimicrobial resistance (AMR). Antibiotics are only required in some mastitis cases, predominantly those caused by Gram positive pathogens. Most Gram negative cases do not require antibiotic therapy. When antibiotics are required, they can be narrow spectrum products to target the bacteria present. Using a narrow spectrum, targeted antibiotic enhances the responsible approach to antibiotic use and can lead to higher cure rates. Therefore, a further benefit of testing is improved mastitis cure rates by targeted treatment leading to fewer mastitis cases. There are fewer cases because the recurrence rate is lower for an individual case and there is less opportunity for infection to spread leading to fewer new cases. Overall this means that the focus can be shifted from treatment of cases to the prevention of new cases, improving overall health and welfare on the farm and increasing productivity and profitability.

A consequence of reduced antibiotic use alongside improved cure rates is that there are likely to be fewer cows that would fail an inhibitory substance test and therefore a reduction in milk antibiotic residues failures. This brings benefits to farmers, vets as well as milk processors and ultimately the consumer. There is lower antibiotic usage, less milk under withdrawal period and fewer cows under treatment to manage accordingly. This means that there is less wasted milk throughout the supply chain.

In conclusion, Mastigram+ is an exciting new on-farm diagnostic test for mastitis in dairy cattle that aids decision making for mastitis treatment. The test is easy and quick to perform and can be straightforwardly incorporated into current workflows. Using the test supports the One Health approach to the responsible use of antibiotics, allowing reduced antibiotic use and targeted narrow spectrum treatment for cases that do require antibiotic therapy. Through using Mastigram+, farms can maximise the chances of treatment success of a case of clinical mastitis and therefore improve productivity and profitability.

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