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Gram negatives: Are they all the same?

Jim Mattox for Progressive Dairy Published on 18 January 2022

Rapid, pathogen-specific treatment is quickly becoming one of the major competitive advantages in milk quality management. Leading dairy farms are implementing on-farm culture systems to quickly diagnose and treat clinical mastitis.

These systems give farms accurate, rapid results in 24 hours or less, allowing them to act with precision and confidence.

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Some progressive dairy farms have been using on-farm culture systems for years, but recent improvements in technology, a push to reduce antibiotics and the growing adaptation of selective dry cow therapy is fueling the market for on-farm mastitis diagnostic tools.

Managing expensive mastitis is all about prevention of new infections. Secondly, accurate diagnosis and treatment of the new clinical infections, especially acute cases, is paramount.

Acute mastitis is defined as the cow showing severe clinical signs of infection, like fever, depression and loss of appetite. The udder is also swollen, hard and painful. The major cause of these acute infections is coliform organisms, or gram-negative bacteria, and the two most prevalent in mastitis are E. coli and klebsiella.

The frustrating part about managing these coliform mastitis cows is: Not only is coliform mastitis the most common type of mastitis, but a high percentage “spontaneously recover” and their body eliminates the causal bacteria (also known as bacteriological cure). In these cases, you have a negative culture test and a less happy and productive cow to deal with, but there’s not much a herd manager can do but administer therapeutic care. However, when you have a confirmed case of coliform mastitis, one major key to success in managing the infection is using on-farm culture systems to help you identify the coliform you’re dealing with. Klebsiella and E. coli are not the same and should be managed differently.

E. coli mastitis is the most common form of mastitis found on a farm, and a high outbreak usually corresponds to a muddy or wet environment. The best way to manage E. coli mastitis is to keep the lying environment clean and dry, as well as using an effective post-teat dipping regimen.

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Cows infected with E. coli mastitis can be negatively impacted by treatment with intramammary antimicrobials and should receive only systemic and supportive therapies, including fluids and anti-inflammatories.

Alternatively, E. coli’s cousin klebsiella should be treated entirely differently. Due to the pervasive nature of the klebsiella bacterium in the dairy environment, facilities and cow hygiene are also the key to prevention. However, the bad news is: Cows infected with klebsiella have a major issue, as it is a very nasty pathogen to manage. The good news is: A study in 2018 indicates that klebsiella mastitis can be successfully treated with intense antibiotic therapy with over a 70% success rate. Unlike E. coli, which has a high “spontaneous cure” rate (over 90%), the spontaneous cure rate for klebsiella is less than that of other coliforms (estimated around 35%), and management of these cases can be very frustrating for the dairy producer.

Cows with klebsiella mastitis should be treated with both systemic and supportive therapies, including fluids, anti-inflammatories and a five-day intensive anti-microbial regimen. Consult your herd veterinarian before implementing any treatment protocols.

The importance of differentiating between E. coli and Klebsiella spp. is based on different effects on production and health of affected cows. Researchers have discovered that new mastitis infections caused by klebsiella were of much longer duration than those infections caused by E. coli. Milk production loss has been demonstrated to be much greater in cases of clinical mastitis caused by Klebsiella spp. compared with E. coli, as is the risk of culling. Negative outcomes such as risk of voluntary dry-off and culling were exacerbated when Klebsiella spp. caused clinical mastitis.

According to a 2019 study, researchers observed differences in outcomes between cases caused by E. coli and Kleb. pneumoniae. The effect of antibiotics on bacteriological cure was pathogen-driven and, regardless of treatment, almost all cases of clinical mastitis caused by E. coli resulted in rapid bacteriological cure.

In contrast, intramammary treatment actually improved bacteriological cure of cases of clinical mastitis caused by Kleb. pneumoniae. Based on these findings and the prevalence of clinical mastitis caused by Kleb. pneumoniae, it is important to distinguish between gram-negative bacteria causing clinical mastitis because the risk of culling and voluntary quarter dry-off were greater for cases of mastitis caused by Kleb. pneumoniae.

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Managers of modern dairy farms must focus on prevention of exposure to gram-negative pathogens and develop rational treatment protocols that limit use of antimicrobials to cases that will not respond satisfactorily to alternative strategies.

Differentiating between gram negatives, gram positives, strep and staph species is important to understand, but also extremely important is further dissecting the gram-negative pathogens into klebsiella and E. coli. The effect of intramammary treatment on clinical outcomes is driven by type of pathogen causing the clinical mastitis cases and, from that point of view, on-farm culture systems are key to differentiating between E. coli and Klebsiella pneumoniae when antibiotic therapy is being considered. end mark

PHOTO: Staff photo.

Jim Mattox
  • Jim Mattox

  • CEO
  • Cowsultants

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