Animal Health Symposium
The Changing Roles of Antibiotics in Animal Health Management – Dr. Jay Johnson, Huvepharma
Dr. Johnson started off the Animal Health Symposium on Saturday, July 17th, by discussing where we currently sit with the use of antibiotics in animal production and why that position has been changing over time. Using an antibiotic is not a simple process, there are many factors that go into giving antibiotics such as regulatory issues, economics, and pressures from consumers. When animals get sick the traditional approaches have been to rely on effective antibiotics to eliminate the pathogen causing the disease. In the last 10 years, the use of medically important antimicrobial drugs approved for use in food-producing animals has declined and the use of not medically important antimicrobial drugs approved for use in food producing animals has increased slightly. Dr. Johnson posed the question: how do we continue that decrease in use of antimicrobials while still maintaining and hopefully improving the immune response in animals? He went on to explain how a multifaceted approach needs to be taken in terms of some management strategies, use of new technologies, and reexamining old practices in terms of vitamins and minerals in the feed to ultimately help animals be the most efficient as possible.
A One-health Perspective on S. aureus Induced Mastitis – Dr. Xin Zhao, McGill University
Dr. Zhao began his presentation by discussing that Staphylococcus aureus is a major opportunistic pathogen that is one of the leading pathogens causing bovine mastitis that is a very devastating and costly disease for the dairy industry and causes mild skin and soft tissue infections to invasive disease in humans. S. aureus infection is difficult to eliminate for multiple reasons such as having the ability to invade cells, to evade the innate immune system through secreting numerous proteins, and to acquire resistance to many antibiotics, most notably methicillin. Currently, the use of cloxacillin and other beta-lactams are ineffective at removing methicillin-resistant S. aureus (MRSA), resulting in culling of infected animals being the major control mechanism. Dr. Zhao then went on to discuss how S. aureus induced mastitis is a good target for the one health approach. MRSA in dairy cows is of human health concern since people working on dairy farms have been shown to carry similar MRSA strains as their cow and a few studies provide indirect evidence supporting the zoonotic potential for S. aureus. Overall, Dr. Zhao emphasized the need for a one-health approach to prevent and treat S. aureus induced mastitis ultimately to ensure producers are providing safe and nutritious milk and milk products to consumers while also protecting the producers being exposed around the animals. New approaches for prevention and treatment for bovine mastitis caused by MRSA need to be studied more.
Biosecure Disposal of Livestock and Poultry Mortalities – Dr. Neslihan Akdeniz, University of Illinois
Dr. Akdeniz is a disposal subject matter expert and her presentation focused on various ways livestock and poultry mortalities can be disposed of while minimizing the spread of the pathogen. The number of animal disease outbreaks is increasing worldwide, and it is critical to have proper disposal of animal mortalities during a disease outbreak to prevent the continued spread. Some of the common disposal methods include burial, incineration, landfilling, and composting; however, environmental concerns, public perception, transportation logistics, and biosecurity restrict the use of some of these methods such as mortalities exceeding the capacity of landfills, transporting the mortalities outside of the production facilities poses biosecurity risks, and burying leads to the risk of pathogen survival and environmental contamination. Composting, however, has evidence of being a biosecure disposal method. Dr. Akdeniz then walked through a few of her studies analyzing various composting systems such as plastic-wrapped composting systems, composting systems with wood-based biochar, pressure utilizing composting systems. She also discussed alkaline hydrolysis of swine mortalities, which alkaline hydrolysis is not a new concept, but is usually done at high temperatures. She wanted to see what would happen if it was done at ambient temperatures, which she concluded that it would eliminate all the pathogens that might concern swine producers as the pH remained above 13 for the duration of the study. Researching and discovering biosecure disposal techniques is critical to ensure there are options available during outbreaks of infectious animal diseases to ultimately prevent further spread of the pathogen.
Tolerance to Bovine Paratuberculosis as Part of the One Health Solution – Dr. Nathalie Bissonnette, Agriculture and Agri-Food Canada
Dr. Bissonnette continued the symposium by discussing bovine paratuberculosis, also known as Johne’s disease (JD), caused by mycobacterium avium subspecies paratuberculosis (MAP). Johne’s disease leads to significant economic and financial losses related to decreased pregnancy rates, reduced milk production, and increased premature culling. Johne’s disease has an unpredictable disease progression and weak sensitivity to diagnostic tests, making it very difficult to control and challenging to detect it. Dr. Bissonnette explained that vaccination does not prevent new infection and currently culling cows is the only solution for JD which is costly. She emphasized the importance of determining the role of genetic susceptibility of cattle to JD, the role of MAP genetics in MAP infection, and the role of immune tolerance and factors that influence the disease progression. The mechanisms of JD pathogenesis are not fully understood, but it is known that MAP infects and uses macrophages as its primary reservoir. One study she discussed specifically analyzed macrophages from cattle diagnosed as positive or negative for JD that were then challenged with live MAP in vitro. Next-generation RNA sequencing revealed that macrophages from positive cows did not have a specific pattern of response to the infection, but in the negative cows a considerable number of genes were differentially expressed. Several immune pathways as well as other pathways related to autoimmune diseases, lipid homeostasis, and hepatic fibrosis responded to the presence of live MAP. Dr. Bissonnette concluded by saying that the results are raising more questions but are ultimately helping to build an understanding of MAP’s controls over the immune response and mechanisms of pathogenesis and survival.
Producing Antibiotic Free Chicken Meat in Developing Countries: What We Learned from Nigeria – Dr. Adelumola Oladeinde, US National Poultry Research Center
Dr. Oladeinde began his presentation by discussing some of his research in progress that has a common goal of working towards the reduction of foodborne pathogens and antimicrobial resistance in poultry production environments. He then set up the rest of his presentation by defining antibiotic stewardship, which is the effort to measure and improve how antibiotics are prescribed by veterinarians and used by animals, and defining one health, which is a holistic approach to comprehensive understanding of antimicrobial resistance (AMR) and ways to address its rising threats. Developing nations, such as Nigeria, have limited studies on AMR prevalence, unregulated access to antibiotics, and use antibiotics in chicken production for therapeutic purposes. Dr. Oladeinde then explained his case study in Nigeria that was focused on determining critical control points for controlling AMR in pre-harvest broiler chicken production and determining the effect of feed source on AMR prevalence. The high levels of antibiotic resistance genes and multi-drug resistant bacteria found to be carried by broiler chicks can potentially be linked to the poor antibiotic stewardship in preharvest. Many of the isolates were resistant to multiple classes of antibiotics, but some were susceptible to cephalosporins and amoxicillin-clavulanic acid that provides us with some hope. Overall, Dr. Oladeinde highlighted that Sub-Saharan African countries, like Nigeria, differ from developed nations in their use and regulation of antibiotics and potentially require a different multipronged one health approach to address these concerns.
Antimicrobial Resistance, Agriculture, and the One Health Continuum – Dr. Ed Topp, Agriculture and Agri-Food Canada
Dr. Topp concluded the Animal Health Symposium by reinforcing the concepts presented by previous speakers. Antimicrobial resistance (AMR) is an issue when a pathogen that is originally sensitive to an antibiotic becomes resistant to that antibiotic, rendering treatment of that infection ineffective. If pathogens become resistant to all antibiotics, there will then no longer be any drugs that can cure or prevent that infection. Dr. Topp discussed how essentially every class of antibiotics brought to market will develop resistance within a few years based on the trends of existing antibiotics. He then defined the one health concept which states that the microbiomes of humans and animals are connected, both directly through contact and indirectly through the environment. Microorganisms can readily be exchanged across the one health continuum as antibiotics are used in food animal production and used by people in community and health care settings. The major concern then is that consumption of antibiotics will result in resistance that develops within the enteric system and is then shed by people and animals, ending up in the environment to complete the continuum and keep the exposure route going. In order to control this exchange, a transdisciplinary approach is required to address issues at the intersection of people, animals, and the environment. One challenge moving forward will be developing ways to reduce AMR without compromising profitability, animal welfare, and food safety.