Intramammary Immunisation Provides Short Term Protection Against Mannheimia haemolytica Mastitis in Sheep

Mastitis affects both dairy and meat/wool sheep industries with losses due to reductions in milk quality and quantity, increased treatment costs and restricted lamb growth. Effective vaccines would be important tools for mastitis control. However, the development of vaccines against mastitis has proved challenging due to the failure to target protective immunity to the mammary gland. In order to target responses to the mammary gland, this study tested whether local administration directly into the gland through the teat canal or in the udder skin confers protection against an intramammary infection. In this study, we tested a vaccine that confers protection against respiratory disease caused by Mannheimia haemolytica to determine if it also protects against intramammary infection by the same organism. No evidence of protection was observed in animals that received a subcutaneous immunisation in the udder skin, however, intramammary immunisation provided almost complete protection against an experimental challenge administered 7 days post immunisation but not if the challenge was delivered 14 days post immunisation. To investigate further the nature of this variation in response, the somatic cell count and concentration of cytokines Interleukin-1β, Interleukin-10 and Interleukin-17A was determined in milk over the course of each study. Intramammary immunisation induced an inflammatory response within the mammary gland, characterised by increases in SCC and in the production of cytokines IL-1β, IL-10, and IL-17A. This response was similar to that observed in un-vaccinated control animals post challenge. The SCC and cytokine levels had returned to levels comparable with un-vaccinated controls prior to challenge at both 7 and 14 days post immunisation. The transient nature of the protective effect is consistent with the priming of an innate antibacterial response within the mammary gland which provides protection against challenge at 7 days but is diminished by 14 days post-vaccination. Further studies are planned to determine the nature of the innate immune mechanisms associated with the protective effect described here to determine whether it may be exploited to improve ruminant udder health.

The fall and rise of group B Streptococcus in dairy cattle: reintroduction due to human-to-cattle host jumps?

Group B Streptococcus (GBS; Streptococcus agalactiae) is a major neonatal and opportunistic bacterial pathogen of humans and an important cause of mastitis in dairy cattle with significant impacts on food security. Following the introduction of mastitis control programs in the 1950s, GBS was nearly eradicated from the dairy industry in northern Europe, followed by re-emergence in the 21st century. Here, we sought to explain this re-emergence based on short and long read sequencing of historical (1953-1978; n = 44) and contemporary (1997-2012; n = 76) bovine GBS isolates. Our data show that a globally distributed bovine-associated lineage of GBS was commonly detected among historical isolates but never among contemporary isolates. By contrast, tetracycline resistance, which is present in all major GBS clones adapted to humans, was commonly and uniquely detected in contemporary bovine isolates. These observations provide evidence for strain replacement and suggest a human origin of newly emerged strains. Three novel GBS plasmids were identified, including two showing >98% homology with plasmids from Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis, which co-exist with GBS in the human oropharynx. Our findings support introduction of GBS into the dairy population due to human-to-cattle jumps on multiple occasions and demonstrate that reverse zoonotic transmission can erase successes of animal disease control campaigns.

Infectious and non-infectious factors affecting somatic cells count and new diagnostic approaches of intramammary infections in dairy goats: A review

Background: Intramammary infections constitute a major animal health and economic problem in commercial dairy goat farms, being responsible for decreases in milk yield, for alter milk composition, and lower milk quality. Objectives: This paper reviews the published literature during last three decades, highlighting the multiplicity of non-infectious and infectious factors that influence somatic cells count (SCC). Besides that, it intends to contributes to understand the conventional diagnostic methods and its limitations, and supports the implementation of new technologies for an efficient mastitis control, including the use of infrared thermography and ultrasonography. Methods: A search on Medline, ScienceDirect and University Institutional Repositories databases was performed using “goats AND mastitis OR intramammary infections OR somatic cells count” for publications from 1990 to present (2020). Results: A total of 144 publications were selected. The SCC is the most important criteria to evaluate the inflammatory status of the mammary glands in goats, but several non-infectious factors (e.g., phenotypic, reproductive, lactational factors) should be taken in consideration for it interpretation. Bacteria and fungi as well lentivirus are commonly responsive for intramammary infections. Intermittent secretion or environmental contamination of milk pathogens, costs and time delay pose challenges using conventional diagnosis methods. Ultrasonographic and thermographic techniques applied to the udder seems to be diagnostic value in acute and chronic mastitis. Conclusions: Unlike other ruminants species, non-infectious factors have a major impact on SCC which should be taken in account for mastitis diagnosis, and according to milk pathogens detection. Further research in imagological techniques is need to accurately contributes to implant new mastitis control strategies.

Reducing antibiotic use in the control of mastitis in dairy herds.

The control of mastitis remains a focus of attention for dairy farmers, veterinary surgeons and advisors due to its impact on cow health and welfare, milk quality, sustainable production, and the financial costs associated with treatment, prevention and ongoing control. In addition, the focus on the unnecessary use of antibiotics in agriculture has meant that mastitis control in dairy herds has received renewed interest, particularly around prevention of new infection and alternative treatment strategies. The latter includes the selective use of intra-mammary antibiotic for infected cows at drying-off, reserving parenteral antibiotic for clinical cases where the cow is ill, and selecting intra-mammary antibiotic treatment for clinical mastitis based on culture results. Treating clinical mastitis caused by Gram-positive pathogens such as Streptococcus spp. with intra-mammary antibiotic remains important to optimise chance of cure and reduce risk of transmission of infection, although antibiotics may not be required for clinical mastitis infections caused by other pathogens, particularly E. coli. The long-term reduction and rationalisation of antibiotic use in mastitis control is achieved through improved management to prevent new infections and avoid the need to treat mastitis. This comes through understanding the predominant epidemiological 'pattern' of infection in the herd and targeted implementation of well-specified interventions to reduce the rate of new infection, either in lactation or during the dry period. For most dairy herds, environmental mastitis pathogens predominate and therefore management and hygiene of housed and pastured environments is a key component of mastitis control plans designed to reduce the need to use antibiotics in mastitis control.

In vitro efficacy of iodine in the pre and post dipping against coagulase negative Staphylococcus isolated in milk of cows with subclinical mastitis

ABSTRACT: The efficiency of the disinfectants used in the milking management is fundamental to the success in the dairy activity, being a critical point to the control of mastitis. The objective was to evaluate the in vitro efficacy of iodine used in pre and post-dipping against coagulase negative Staphylococcus (CNS). Thus, 53 CNS isolates were studied for the action of the 1.0% disinfectant and their serial dilutions of 0.5%, 0.375% and 0.25%, in addition to two commercial presentations of iodine in concentrations of 0.5% and 0.25%. The rate of CNS inhibition achieved by iodine at 0.375%, 0.5% and 1.0% for 60 seconds, was 60.4%. In 30 seconds, iodine at 0.5% and 1.0% showed a microbial inhibition rate of 52.8% and 56.6%, respectively. The other protocols tested were less efficient. It is concluded that the greatest in vitro disinfectant activity for CNS was demonstrated by iodine at 0.375%, 0.5% and 1.0%, for 60 seconds. Microbial susceptibility tests should be carried out periodically, as well as health education practices and corrective training on the property, in order to ensure udder health and mastitis control.

Overview of Research Development on the Role of NF-κB Signaling in Mastitis

Mastitis is the inflammation of the mammary gland. Escherichia coli and Staphylococcus aureus are the most common bacteria responsible for mastitis. When mammary epithelial cells are infected by microorganisms, this activates an inflammatory response. The bacterial infection is recognized by innate pattern recognition receptors (PRRs) in the mammary epithelial cells, with the help of Toll-like receptors (TLRs). Upon activation by lipopolysaccharides, a virulent agent of bacteria, the TLRs further trigger nuclear factor-κB (NF-κB) signaling to accelerate its pathogenesis. The NF-κB has an essential role in many biological processes, such as cell survival, immune response, inflammation and development. Therefore, the NF-κB signaling triggered by the TLRs then regulates the transcriptional expression of specific inflammatory mediators to initiate inflammation of the mammary epithelial cells. Thus, any aberrant regulation of NF-κB signaling may lead to many inflammatory diseases, including mastitis. Hence, the inhibiting of NF-κB signaling has potential therapeutic applications in mastitis control strategies. In this review, we highlighted the regulation and function of NF-κB signaling in mastitis. Furthermore, the role of NF-κB signaling for therapeutic purposes in mastitis control has been explored in the current review.

Dry cow environment management and mastitis control in dairy herds

Advice regarding the management and importance of the dry cow environment can be difficult to offer in many dairy herds for several reasons. These may include a perception that dry cow therapy (both internal teat sealant and antibiotic) is extremely effective at preventing infection, a lack of milk recording and/or mastitis data to enable analysis of mastitis epidemiology, suboptimal housing, a fundamental lack of focus on the dry period in favour of continued focus on milking hygiene and lactating cow management, or a combination of several of these reasons. However, for many herds that struggle to control mastitis, improving the dry cow environment will pay huge dividends in terms of reducing dry period new infection and improving apparent dry period cure rate. This article sets out those areas of dry cow environment management which appear particularly important for herds and their veterinary advisors to consider, and gives examples of improved control of mastitis following dry cow interventions for a spring calving, autumn calving and all year round calving herd.

Point-of-care tests for bovine clinical mastitis: what do we have and what do we need?

Mastitis, inflammation of the bovine mammary gland, is generally caused by intramammary infection with bacteria, and antimicrobials have long been a corner stone of mastitis control. As societal concern about antimicrobial use in animal agriculture grows, there is pressure to reduce antimicrobial use in dairy farming. Point-of-care tests for on-farm use are increasingly available as tools to support this. In this Research Reflection, we consider available culture-dependent and culture-independent tests in the context of ASSURED criteria for low-resource settings, including convenience criteria, scientific criteria and societal criteria that can be used to evaluate test performance. As tests become more sophisticated and sensitive, we may be generating more data than we need. Special attention is given to the relationship between test outcomes and treatment decisions, including issues of diagnostic refinement, antimicrobial susceptibility testing, and detection of viable organisms. In addition, we explore the role of technology, big data and people in improved performance and uptake of point-of-care tests, recognising that societal barriers may limit uptake of available or future tests. Finally, we propose that the 3Rs of reduction, refinement and replacement, which have been used in an animal welfare context for many years, could be applied to antimicrobial use for mastitis control on dairy farms.

James Morley Booth

Having gained clinical experience in practice, James joined the Milk Marketing Board where his passion for mastitis control and dairy health helped to improve milk quality.

The fall and rise of group B Streptococcus in dairy cattle: suspected reintroduction from a human reservoir

Streptococcus agalactiae, also known as group B Streptococcus (GBS), is a pathogen of humans and cattle, in which it is responsible for carriage or invasive disease and subclinical mastitis, respectively. From the 1950s to 1970s, thanks to successful mastitis control programs, the prevalence of GBS fell in the Swedish cattle population, but it re-emerged in the late 1990s. GBS was thought to consist of host-specific subpopulations but recent studies have shown that human and cattle subpopulations overlap, with different accessory genome elements providing survival advantages in each host species. We hypothesized that cattle-adapted GBS was eradicated and replaced by new GBS strains of human origin. Our aim was to explore the differences in GBS cattle population over six decades (pre-post non-detection), with a focus on the possible role of MGE in the evolution of these strains. Historical (n = 44, 1953 to 1978) and contemporary (n = 76, 1997 to 2012) GBS isolates from bovine milk samples were sequenced and analysed for WGS-MLST. Phylogenetic network analysis revealed the presence of six major clades: two of these were detected only up to 1970, two were only detected after 2004, and two were detected in both periods. Historical isolates were all tetracycline sensitive, whereas 51% of recent isolates harboured tet(M), which is considered a marker of human adaptation. Our data support the elimination of a bovine specific clade (CC61/67) and the emergence of new clades (CC1, CC103/314) that are likely of human of origin.