Recurrent mastitis-persistent or new infections?

Recurrent clinical mastitis contributes to around half of all infections having an economic impact in the dairy industry. It leads to milk yield reduction, increased risk of mortality, and culling, and may be caused by new infections or a persistent infection after previous treatment. Disease management is dependent on the infecting species, necessitating accurate identification of the pathogen in the range of persistent and reinfection cases among recurrent infections using culture and molecular biological analysis. Milk samples from diagnosed clinical mastitis cases were collected from three Northern German dairy farms between 2011 and 2015. Totally, 2043 diagnosed mastitis cases were examined at quarter level (1598 (78.2 %) first and 445 (21.8 %) recurrent mastitis cases in lactation). Among the recurrent cases, 145 (32.6 %) cases were confirmed to harbor the same pathogenic species as previous infections. RAPD PCR confirmed the same species strain in 49 (11 %) of the recurrent infections. The contribution of new infections as compared to persistent infections in cases of clinical mastitis is clear from the data. Future studies in recurrent clinical mastitis control should be focused on influencing factors to prevent new infections in addition to therapeutic intervention and bacteriological cure.

[Evidence-based aspects of clinical mastitis treatment]. / Aspekte einer evidenzbasierten Therapie klinischer Mastitiden.

Mastitis is one of the most common and expensive diseases in dairy cattle. The decision to treat clinical mastitis is usually made without any knowledge of the etiology, and can therefore only be evidence-based to a limited extent. Evidence-based medicine relies essentially on a combination of one's own clinical competence and scientific findings. In mastitis therapy, those insights depend mostly on pathogen-specific factors. Therefore, in evidence-based therapeutic decision making the pathogen identification should serve as a basis for the consideration of scientifically validated therapeutic concepts. The present paper considers evidence-based treatment of clinical mastitis based on a literature review. The authors conclude that an anti-inflammatory treatment using an NSAID should be conducted regardless of the pathogen. However, the choice of an antibiotic therapy depends on the mastitis causative pathogen, clinical symptoms and the animal itself. In principle, a local antibiotic treatment should be chosen for mild and moderate mastitis. It should be noted, that the benefit of an antibiotic therapy for coliform infections is questionable. With knowledge concerning the pathogen, it appears entirely reasonable to refrain from an antibiotic therapy. For severe (i.   e. feverish) mastitis, a parenteral antibiotic therapy should be selected. An extension of the antibiotic therapy beyond the manufacturer's information is only reasonable for streptococcal infections. It is important to make the decision on a prolonged antibiotic therapy only with the knowledge of the mastitis-causative pathogen. In terms of the therapy of a staphylococcus or streptococcus infection, a narrow-spectrum antibiotic from the penicillin family should be adopted when selecting the active agents.