Abstract
Bovine mastitis is an ongoing significant concern in the dairy and agricultural industry resulting in substantial losses in milk production and revenue. Among the predominant etiological agents of bovine mastitis are Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, and Escherichia coli. Currently, the treatment of choice for bovine mastitis involves the use of commercial therapeutic antibiotic formulations such as TerrexineTM, containing both kanamycin and cephalexin. Such antibiotics are regularly administered in more than one dose resulting in the withholding of milk for processing for a number of days. Here, we describe the optimization of a formulation of Lactococcus lactis DPC3147, that produces the two-component bacteriocin lacticin 3147, in a liquid paraffin-based emulsion (formulation hereafter designated ‘live bio-therapeutic’) for the first time and compare it to the commercial antibiotic formulation TerrexineTM, with a view to treating cows with clinical/sub-clinical mastitis. Critically, in a field trial described here, this ‘ready-to-use’ emulsion containing live L. lactis DPC3147 cells exhibited comparable efficacy to TerrexineTM when used to treat mastitic cows. Furthermore, we found that the L. lactis cells within this novel emulsion-based formulation remained viable for up to 5 weeks, when stored at 4, 22, or 37°C. The relative ease and cost-effective nature of producing this ‘live bio-therapeutic’ formulation, in addition to its enhanced shelf life compared to previous aqueous-based formulations, indicate that this product could be a viable alternative therapeutic option for bovine mastitis. Moreover, the single-dose administration of this ‘live bio-therapeutic’ formulation is a further advantage, as it can expedite the return of the milk to the milk pool, in comparison to some commercial antibiotics. Overall, in this field trial, we show that the live bio-therapeutic formulation displayed a 47% cure rate compared to a 50% cure rate for a commercial antibiotic control, with respect to curing cows with clinical/sub-clinical mastitis. The study suggests that a larger field trial to further demonstrate efficacy is warranted.
Highlights
Mastitis is a persistent and financially important disease in dairy cows due to the costs associated with antibiotic treatment, discarded milk, reduced milk production and veterinary costs
Viability of the L. lactis DPC 3147 cells was investigated daily for up to 5 days in four formats: (i) non-freeze dried cells re-suspended after centrifugation in water for injection (WFI) (Figure 1B); (ii) non-freeze dried cells re-suspended in a liquid paraffin/polysorbate 80-based emulsion (Figure 1C, ‘live biotherapeutic’ formulation); (iii) freeze-dried cells re-suspended in WFI (Figure 1D) and iv) freeze-dried cells in a liquid paraffin/polysorbate 80-based emulsion (Figure 1E)
The viability of freeze-dried cells in emulsions stored at 22◦C and 37◦C (Figure 1E) were more stable than corresponding freeze-dried cells stored in WFI (Figure 1D)
Summary
Mastitis is a persistent and financially important disease in dairy cows due to the costs associated with antibiotic treatment, discarded milk, reduced milk production and veterinary costs. In the event of antibiotic treatment failure, the cows may have to be culled. One study estimated that mastitis resulted in a net farm profit decrease ranging between $19,132 to $91,552 per herd, predominantly due to culling cows and decreases in milk production (Guimarães et al, 2017). Antibiotic resistance (AMR) is a global problem resulting in higher healthcare-associated costs, treatment failure and deaths (European Centre for Disease Prevention and Control [ECDC], 2014). It is essential that preventative strategies and alternative treatment plans are devised to reduce reliance on antibiotics in the dairy herd, which is in line with Action 6 of the European Commission’s Roadmap against AMR (European Commission [EC], 2015)
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