Antimicrobial Resistance: the use of antimicrobials in the Livestock Sector

The use of antimicrobials in livestock production provides a basis for improving animal health and productivity. This in turn contributes to food security, food safety, animal welfare, protection of livelihoods and animal resources. However, there is increasing concern about levels of antimicrobial resistance in bacteria isolated from human, animal, food and environmental samples and how this relates to use of antimicrobials in livestock production. The report examines antimicrobial usage in livestock and its impact on public health and the food economy. Policy issues and knowledge gaps to manage antimicrobial use and the risk of antimicrobial resistance are identified and discussed

Antimicrobial resistance surveillance in feedlot cattle

2011 Spring.Includes bibliographical references.Objectives: To develop and validate methodological components of a model for surveillance of antimicrobial use and resistance in feedlot cattle. Methods: A web-based survey of participants knowledgeable and interested in antimicrobial use in beef feedlots was used to solicit responses regarding appropriate metrics for quantifying, analyzing, and reporting antimicrobial exposures. The accuracies of two susceptibility tests commonly recommended for surveillance programs were determined using stochastic latent class analysis. Multivariable logistic and linear regression was used to investigate associations between exposures to antimicrobial drugs and antimicrobial resistance. Results: When reporting antimicrobial use in the context of antimicrobial resistance, survey participants believed that the Animal Defined Daily Dose metric was the most accurate. The two susceptibility tests investigated had comparable accuracies for the antimicrobial drugs tested. Exposure to parenteral tetracycline in the study feedlots was associated with resistance to tetracycline; however, exposures to all other classes of antimicrobials were not associated with antimicrobial resistance. Conclusions: Appropriate metrics for reporting and analyzing antimicrobial resistance are necessary to accurately investigate associations between use and resistance, though clarity of what the metric represents may be lost. Testing of susceptibility in surveillance programs is equally valid by way of disk diffusion testing. Multivariable logistic regression was an appropriate and useful method to investigate associations between use and resistance. Parenteral exposures to antimicrobials did not drive antimicrobial resistance at mid-feeding period

Practical use of registered veterinary medicinal products in Macedonia in identifying the risk of developing of antimicrobial resistance

The use of antimicrobial agents is the key risk factor for the development and spread of antimicrobial resistance. It is therefore generally recognized that data on the usage of antimicrobial agents in food-producing animals are essential for identifying and quantifying the risk of developing and spreading of antimicrobial resistance in the food-chain. According to the WHO guidelines, the Anatomical Therapeutic Chemical system for the classification of veterinary medicines (ATC-vet) is widely recognized as a classification tool. The aim of this work is to analyze the list of registered veterinary medicinal products in R. Macedonia and to evaluate the quality and practical use of this list according to the ATC-vet classification in order to identify the risk of developing and spreading of antimicrobial resistance

Value of Arrival Metaphylaxis in U.S. Cattle Industry

Although several studies have estimated economic impacts of antimicrobials for growth promotion, little is known about economic impacts of the common animal health management strategy known as metaphylaxis: administering antimicrobials to groups of animals to prevent disease. This article develops a new framework to map animal disease to producer profitability and determine societal economic impacts surrounding metaphylactic use of antimicrobials in beef cattle production. Results indicate the direct net return value of metaphylaxis to the U.S. fed cattle industry is at least $532 million. Beef producer surplus losses of$1.8 billion would be associated with eliminating metaphylaxis

Quantifying and predicting antimicrobials and antimicrobial resistance genes in waterbodies through a holistic approach: a study in Minnesota, United States

AbstractThe environment plays a key role in the spread and persistence of antimicrobial resistance (AMR). Antimicrobials and antimicrobial resistance genes (ARG) are released into the environment from sources such as wastewater treatment plants, and animal farms. This study describes an approach guided by spatial mapping to quantify and predict antimicrobials and ARG in Minnesota’s waterbodies in water and sediment at two spatial scales: macro, throughout the state, and micro, in specific waterbodies. At the macroscale, the highest concentrations across all antimicrobial classes were found near populated areas. Kernel interpolation provided an approximation of antimicrobial concentrations and ARG abundance at unsampled locations. However, there was high uncertainty in these predictions, due in part to low study power and large distances between sites. At the microscale, wastewater treatment plants had an effect on ARG abundance (sul1 and sul2 in water; blaSHV, intl1, mexB, and sul2 in sediment), but not on antimicrobial concentrations. Results from sediment reflected a long-term history, while water reflected a more transient record of antimicrobials and ARG. This study highlights the value of using spatial analyses, different spatial scales, and sampling matrices, to design an environmental monitoring approach to advance our understanding of AMR persistence and dissemination

Quantifying the effect of natural microflora on growth of salmonellae in fresh pork

This study was undertaken to provide predictive models to help prevent health problems in relation to salmonellae in fresh pork. The models consider different time and temperature of storage as well as microbial interaction with the natural microflora in the meat. At six temperatures between 4 and 20°C, duplicate growth curves of Salmonella Typhimurium DT104 and Salmonella Derby were established in both sterile (irradiated) minced pork as well as in minced pork with a natural microflora

Development of an enhanced methodology for large-scale detection and quantification of antimicrobial resistant bacteria in livestock

Antimicrobial resistance (AMR) is a global health challenge for both humans and animals. A potential source of antimicrobial resistant bacteria is in livestock due to the widespread and unrestrained use of antimicrobials. This is further exacerbated by the presence of bacteria resistant to critically important antimicrobials (CIAs) that are classified as the last-line of treatment of infectious diseases in humans. AMR surveillance in livestock has become a key cornerstone of AMR control strategies by informing the presence and frequency of resistance including CIA-resistant bacteria. Established approach of AMR surveillance in livestock typically have a national-level focus that only acquire a maximum of 300 isolates nationwide for antimicrobial susceptibility testing (AST), with each isolate representing one sample from one farm. While this approach is sufficient for evaluating AMR at national-level, it is inadequate for AMR surveillance at herd-level as one isolate is not sufficient to represent AMR of each farm, leading to errors when implementing antimicrobial stewardship and AMR control measures at the herd-level. This project aimed to address this issue by developing an enhanced AMR surveillance method that combines a multiple samples per herd approach with automated laboratory robotics and selective agars incorporated with antimicrobials to provide accurate large-scale data on the presence, frequency and carriage levels of resistant bacteria within individual farms. The first step in developing the enhanced method was validating suitable selective agars for enumeration of resistant E. coli colonies. Of the three E. coli selective agars compared, MacConkey agar was found to be consistently inferior in E. coli growth performance than the two modern commercially available E. coli selective agars, Brilliance™ E. coli and CHROMagar™ ECC. This inferiority in E. coli growth performance was consistently seen regardless of whether pure cultures or homogenised faecal samples were used for inoculation onto E. coli selective agar with or without incorporation of antimicrobials. Brilliance™ ESBL and CHROMagar™ ESBL which are two modern commercially available selective agar targeting extended-spectrum cephalosporin (ESC)-resistant E. coli were also compared to determine which is better suited for quantifying ESC-resistant E. coli. The latter was found to be more suitable compared to the former due to being able to support a wider diversity of ESC-resistant E. coli strains. The chosen selective agars were subsequently applied to the enhanced method to describe the CIA-resistance scenario of Australian pigs in order demonstrate its capability to provide a more accurate and detailed AMR data at the herd, state and national-level. A major finding was the detection of CIA-resistant E. coli in Australian pigs. Fluoroquinolone (FQ)-resistant E. coli was present among majority of Australian pig farms nationwide, while the presence of ESC-resistant E. coli was detected among eight Australian pig farms nationwide, with the former having a higher frequency compared to the latter. However, compared to the commensal E. coli population, carriage levels of both resistant E. coli were lower, indicating that CIA-resistant E. coli has not yet spread throughout the commensal E. coli population. When subjected to AST, CIA-resistant E. coli harbouring phenotypic resistance towards FQ and ESC was detected but due to the nature of FQ-resistance mechanisms, it has limited clinical relevance. Whole genome sequencing (WGS) was also performed on CIA-resistant E. coli which revealed that ST744 and ST4981 are the current dominant FQ-resistant E. coli and ESC-resistant E. coli sequence types (STs) respectively present among Australian pigs nationwide. Further analysis suggests that both STs were likely introduced into Australian pigs via external sources. Nonetheless, the multiple samples per herd approach and quantitative focus of the enhanced method demonstrated that it is capable of delivering a more accurate and detailed AMR data at the herd-level compared to established AMR surveillance systems. The adaptability of the enhanced method towards a different livestock species was demonstrated through the performance of AMR surveillance on ten Australian meat chicken farms. While ESC-resistant E. coli was not detected, ciprofloxacin-resistant E. coli was detected on all farms, with carriage levels that were lower than commensal E. coli. This indicates that FQ-resistant E. coli is present among all ten farms but has not yet spread throughout its commensal E. coli population. When subjected to AST, only 57.1% of FQ-resistant E. coli isolates were multi-class resistant, and that the most common phenotypic resistance profile was one with resistance towards two antimicrobial classes. Though WGS will be conducted to ascertain the genomic characteristics of FQ-resistant E. coli isolates in these ten farms, the findings demonstrated that the enhanced method is also capable of delivering the same accurate and detailed AMR data at the flock-level for meat chickens. In conclusion, the findings demonstrated that the enhanced method is capable of delivering a more accurate and detailed AMR data than established AMR surveillance systems for livestock at all levels of governance, and with different livestock species. This ultimately leads to improved judgements when implementing AMR control strategies as part of biosecurity protocols to prevent further emergence and spread of CIA-resistant E. coli. Additionally, it provides further prospects for expanding the application of the enhanced method within the food and public health sectors, with further opportunities for enhancement via the inclusion of data pertaining to antimicrobial use and resistance transmission pathways

Epidemiology of Veterinary Antimicrobial Use in Tennessee and Strategies for Antimicrobial Stewardship

Antimicrobial drugs are used for maintaining or improving animal health. Non-judicious antimicrobial use (AMU) is a modifiable factor driving antimicrobial resistance (AMR). Using qualitative and quantitative approaches, this doctoral dissertation examined the epidemiology of veterinary AMU among clinicians at The University of Tennessee Veterinary Medical Center (UTVMC), and cattle producers in Tennessee (TN), and identified strategies for antimicrobial stewardship (AMS). First, an online survey was sent to UTVMC clinicians to identify factors influencing their AMU practices, analyze their concerns regarding AMU and AMR. Compared to clinicians who obtained their veterinary degree from 1970–1999, those who graduated from 2000–2009 and 2010–2016 were 3.96 (P = 0.034) and 5.39 (P = 0.01) times less concerned about AMR, respectively. Second, a qualitative study was undertaken to identify and document the factors driving AMU, alternatives, knowledge, and perceptions towards AMU among TN beef cattle producers. The findings suggested that clinical signs, culture & susceptibility testing drive AMU and more awareness of drivers for AMR, and continuing education for producers on prudent AMU is needed. Third, a mixed methods study that was conducted with TN dairy producers showed that use of culture and sensitivity test results for antimicrobial selection was a widespread and common practice, and blanket dry cow therapy was still commonly practiced. Fourth, a survey of TN beef cattle producers was conducted to identify the factors driving their AMU, as well as their alternatives, knowledge, and perceptions towards AMU. The findings showed that controlling for type of cattle operation, age was significantly associated with the producer’s degree of concern about AMR (P = 0.022). Additionally, survey findings suggested a need to promote the use of written antimicrobial treatment protocols among TN beef producers, and continued training for producers on infection prevention/control and prudent AMU. Fifth, a mixed methods study was conducted to identify the perceptions of TN cattle producers regarding the Veterinary Feed Directive. The findings suggested a likely compensatory increase in the use of injectable antimicrobials for therapeutic and prophylactic purposes that should be further investigated. Overall, the entire project identified key strategies for improving AMU in TN

A One Health genomic approach to antimicrobial resistance is essential for generating relevant data for a holistic assessment of the biggest threat to public health

© 2019 Microbiology Australia. All rights reserved. Antimicrobial resistance (AMR) threatensmodernmedicine asweknow it.AMR infectionsmay ultimately beuntreatable and routine surgeries will become inherently risky1. By 2050 more people may die of drug-resistant infections (DRIs) every year than of cancer, which equates to more than 10 million annual deaths globally2 and the World Bank has estimated that AMR could cost the global economy 1 trillion every year after 2030.DRIs alsolead to an increase in the length of hospital stays, the use of more toxic or costly antibiotics and an increased likelihood of death3. BRIC nations (Brazil, Russia, India, China) and socio-economically challenged countries and people who already have higher rates of infectious diseases will feel the greatest impact2. Indeed, AMR has been likened to the 2008 global financial crisis on an annual repeat cycle.Thatis because the effects of AMR are not just confined to the human medical sector. The veterinary sector is also reliant on the availability of antimicrobials to treat infectious diseases in companion and food-producing animals