Use Of Antimicrobials In Livestock Research Articles

Prevalence and Antimicrobial Susceptibility of Foodborne Pathogens from Raw Livestock Meat in China, 2021

The rising prevalence of pathogenic bacteria in livestock meat poses a growing public health concern in China. The determination of antimicrobial resistance (AMR) is critical for the clinical management of foodborne infections stemming from livestock meat consumption. This study aimed to assess the prevalence of pathogenic bacteria in livestock meat (pork, beef, and mutton) sampled in China in 2021 and to identify the most common AMR patterns among the isolated pathogens. A total of 2515 raw livestock meat samples were collected across 15 provinces in China during 2021. Pathogen detection, including Listeria monocytogenes, Salmonella, and diarrheagenic Escherichia coli (DEC), followed China’s national food safety standards. All Salmonella isolates underwent serotyping via slide agglutination. Antimicrobial susceptibility of Salmonella and DEC isolates was assessed using the broth dilution method. The detection rates for L. monocytogenes, Salmonella, and DEC in raw livestock meat were 9.06% (228/2, 515), 10.54% (265/2, 515), and 6.16% (155/2, 515), respectively. Pork showed the highest contamination rates for Salmonella and DEC, with prevalence rates of 17.60% (214/1, 216, χ2 = 124.62, p < 0.05) and 7.89% (96/1, 216, χ2 = 14.466, p < 0.05), respectively. L. monocytogenes contamination was notably higher in chilled (14.43%, 84/582) and frozen (12.39%, 55/444) meat than in fresh meat (χ2 = 43.510, p < 0.05). In contrast, Salmonella (12.09%, 180/1489, χ2 = 15.173, p < 0.05) and DEC (7.25%, 108/1489, χ2 = 12.275, p < 0.05) were more prevalent in fresh meat than in chilled or frozen samples. The predominant Salmonella serotypes identified were Salmonella enterica subsp. enterica serovar Typhimurium, followed by Salmonella enterica serovar Derby, Salmonella enterica serovar Rissen, Salmonella enterica serovar London, and Salmonella enterica serotype Enteritidis. Enteroaggregative E. coli was the most frequent pathotype among DEC (84.7%, 133/157), followed by enteropathogenic E. coli (8.3%, 13/157) and enterohemorrhagic E. coli (5.1%, 8/157). Among the 14 tested antimicrobial agents, Salmonella isolates demonstrated an overall resistance rate of 87.50%, while DEC exhibited a resistance rate of 84.70%. Ampicillin and tetracycline showed the highest resistance rates in both pathogens. Multi-drug resistance (MDR) was observed in 67.53% of Salmonella isolates (183 isolates) and 57.96% of DEC isolates (91 isolates). This study highlights the significant contamination of retail raw livestock meat in China by L. monocytogenes, Salmonella, and DEC. The high resistance of MDR in both pathogens poses serious public health risks. Chinese food safety and veterinary authorities should implement stricter measures to control pathogen contamination and regulate the use of antimicrobials in livestock to mitigate these risks.

Harnessing the Potential of Living Labs in European Research Projects on Agriculture. The Case of Promoting Prudent Use of Antimicrobials in Livestock

SummaryThe urgency to reduce the use of antimicrobials in the livestock sector has become part of the European Farm‐to‐Fork agenda. To develop innovations and pave the way for prudent antimicrobial use (AMU), the H2020 four‐year‐long ROADMAP project implemented the approach of Living Labs (LL). It stands for a process that involves a heterogeneous group of stakeholders in co‐creation, testing and evaluating innovations in real‐world contexts. The use of LLs has gained momentum to accelerate transformation of European agriculture by developing innovations through end‐user (farmer) involvement. However, the LL‐approach is new in the livestock sector. During the project, 11 LLs were established in seven European countries, each with its own settings but linked to the project's overarching goals. Some LLs developed a common understanding of AMU within the sector or between farmers and veterinarians, while others focussed on policy development or better management practices. During the ROADMAP project, we learned about the potential and limitations of the LL approach in the livestock sector. Using the approach of social innovations, we developed recommendations on how to realise the potential of LLs in a research context to meet the goals of the EU Farm‐to‐Fork strategy of prudent AMU.

Mandatory vs. Voluntary? How to Conceive and Implement the ‘Right’ Measures to Fight AMR

SummaryThe fight against antimicrobial resistance (AMR) usually relies on a large set of measures, such as banning or restricting the use of certain molecules, promoting preventive approaches to animal health, monitoring antibiotic use and prescription, training farmers and veterinarians, developing quality schemes and labels, etc. These measures can be mandatory (i.e. regulations) or voluntary (i.e. private standards, professional guidelines, etc.), depending on the policy style adopted in each country: imposing the same framework of action for everyone or trying to stimulate stakeholders’ initiatives. It is however difficult to say that one option is better than another, given that reduction of antimicrobial use in livestock has been achieved in different European countries using different options. Based on a cross‐reflection from three ROADMAP case studies, this Point de Vue argues that an efficient and legitimate AMR policy has to adopt a combination of voluntary and mandatory measures which is carefully thought through and which is adapted to local contexts and dynamics.

Antimicrobials Use by Smallholder Dairy Farmers in Peri-Urban Area of Nakuru Kenya: Knowledge, Attitudes and Practices

In dairy intensification, mastitis infections become prevalent and induce frequent Antimicrobial Use (AMU), sometimes inappropriately. This poses public health risks because of growing Antimicrobial Resistance (AMR), which calls for stewardship programs informed by Knowledge, Attitude and Practices (KAPs) about AMU and AMR to halt or reverse the worrying trend. Data was obtained in cross sectional survey conducted in four peri-urban wards around Nakuru city in Kenya. Randomly selected sample farmers (n=124) with free-grazing, semi-zero-grazing or zero-grazing dairy management, representing increasing dairy intensification levels provided data on the KAPs. Chi-square test statistics was fitted to establish associations between KAPs and dairy intensification levels. Among the sample farmers, six in ten (58.8 percent) had intensified dairy production, at least six in ten were marketing milk through informal outlets and were using antimicrobial drugs. Compliance with the withdrawal period was high and increased (p<0.05) with increasing intensification from free-grazing to zero-grazing. Within antibiotic withdrawal period, at least seven in ten farmers did not sell milk, fewer than four in ten consumed their milk at home and fewer than three in ten fed the milk to calves. Though independent of dairy intensification level (p>0.05), using antimicrobials for mastitis treatment increased while sourcing information on antimicrobial use from extension and veterinary officers decreased, with increasing intensification level. Farmers with some training on prudent antimicrobial use and with positive attitudes that milk from antimicrobial treated cows is unsafe, antimicrobial resistant pathogens and residues can be passed from milk to humans, mastitis can be treated without antimicrobial drugs, and antimicrobial residues can end up accumulating in the soils increased (p>0.05) with increasing dairy intensification levels. These results show that regarding AMU and AMR, farmers become more knowledgeable, with positive attitudes and good practices as they intensify their dairy management. The implication is that intensification of dairy management motivates farmers to gain more knowledge, acquire positive attitudes and apply good practices towards responsible prudent use of antimicrobials in livestock. Therefore, strengthening stewardship with targeted training and sensitization can foster prudent and responsible antimicrobial use.

Escherichia coli isolates from vegetable farms in Addis Ababa, Ethiopia: Antimicrobial susceptibility profile and associated resistance genetic markers.

The use of animal manure to fertilize soil is an emerging concern contributing to the transfer of antimicrobial-resistant pathogens to vegetables. Hence, assessing antimicrobial susceptibility profile of Escherichia coli in vegetable farms is essential to design appropriate interventions against antimicrobial resistance (AMR) in the food chain. This study assessed antimicrobial resistance profile and associated genetic markers among E. coli isolated from vegetable farms fertilized with animal manure in Addis Ababa, Ethiopia. A total of 1044 samples were collected using convenience sampling: soil (n = 271), manure (n = 375), and vegetables (n = 398) from 81 vegetable farms in Addis Ababa, Ethiopia. Antimicrobial susceptibility test was conducted for 100 E. coli isolates and antimicrobial resistance genes (ARGs) were tested by polymerase chain reaction (PCR). Of the 1044 collected samples, 25.3% were positive for E. coli, with significantly higher prevalence in the manure sample and samples collected from Akaki Kality sub-city (p < .05). The highest resistance rate was recorded for tetracycline (72%), followed by streptomycin (63%), and sulfamethoxazole +trimethoprim (56%). Multidrug resistance was detected in 61% of the E. coli isolates. The aac(3)-IV (76.9%), bla TEM (65.4%), aadA (60.3%), tet(A) (58.3%), and sulI (51.7%) were the commonly detected resistance genes. The current study showed a high burden of antimicrobial resistance among E. coli isolated from manure-amended vegetable farms, with potential of playing a significant role in the dissemination of antimicrobial resistance in the food chain. Efforts should be made to reduce the burden of resistant organisms and ARGs through prudent use of antimicrobials in livestock and application of appropriate composting techniques before using manure as fertilizer.

Economic assessment of an intervention strategy to reduce antimicrobial usage in small-scale chicken farms in Vietnam

Antimicrobials are a core aspect of most livestock production systems, especially in low-and middle-income countries. They underpin the efficient use of scarce feed resources and stabilize returns on capital and labor inputs. Antimicrobial use (AMU) contributes to the production of healthy animals, yet AMU in livestock is linked to antimicrobial resistance (AMR) in animals, humans and the environment.The Vietnamese Platform for Antimicrobial Reduction in Chicken Production was implemented during 2016–2019 and was one of Southeast Asia's first interventions focused on AMU reductions in livestock production. The project targeted small-scale commercial poultry farms in the Mekong Delta region of Vietnam using a “randomized before-and-after controlled” study design. It provided farmers with a locally adapted support service (farmer training plan, advisory visits, biosecurity, and antimicrobial replacement products) to help them reduce their reliance on antimicrobials. A partial budget analysis was performed comparing the control group (status-quo) and intervention group (alternative). The median net farm-level benefit of the intervention strategies with the project's support was VND 6.78 million (interquartile range (IR) VND -71.9–89 million) per farm. Without project support the benefit was reduced to VND 5.1 million (IR VND -69.1–87.2 million) to VND 5.3 million (IR -VND 68.9–87.5 million) depending on the antimicrobial alternative product used. At the project level with a focus on AMU and its reduction, subsequently influence on the resistance reduction, our results showed that achieving resistance reduction benefits with the current knowledge and technologies required investment of at least VND 9.1 million (US$ 395.10) per farm during the project's lifetime. The results highlight the positive net profit for the majority of enrolled farms and a reasonable investments from the project. The recommendation focuses on the implementation of policies on financial support, legislation, and information as potential solutions to facilitate the application of intervention strategies to reduce AMU in poultry production.

Associations of the Swiss national reporting system's antimicrobial use data and management practices in dairy cows on tiestall farms

Antimicrobial use (AMU) in Switzerland is above target and requires reduction, especially in dairy cattle. Measuring AMU is pivotal to identifying starting points for AMU reduction, and so are studies investigating its potential drivers in dairy farms worldwide. However, although AMU in dairy farms is high, studies estimating AMU specifically in tiestall farms are scarce. Tiestalls are a common housing system and their prevalence among dairy farms accounts to approximatively 73%, 41%, and 40% in Canada, the United States, and Switzerland, respectively. The objectives of this cross-sectional, retrospective observational study were to estimate AMU using the newly established Swiss national reporting system for AMU in livestock and to identify associated factors on Swiss tiestall dairy farms. We calculated the treatment incidence (TI) by using the European Medicines Agency methodology and their defined daily dose (DDD) and defined course dose (DCD) standards. Data on factors potentially associated with AMU were obtained through personal interviews with farm managers on 221 farms. Retrospectively, during a 1-year period, data on a total of 7,619 treatments were extracted from the national database. Associations between management factors and TI were analyzed using a generalized linear model with gamma distribution. The mean (± SD) overall TI was 5.46 DDD/cow-year (± 4.10 DDD/cow-year). Intramammary treatment during lactation accounted for highest TI (3.24 ± 3.16 DDD/cow-year), whereas dry-cow therapy accounted for lowest TI (0.44 ± 0.49 DCD/cow-year). We found that 5 of the investigated management factors were significantly associated with TI. Organic production (estimate = -2.16; 95% CI = -3.62 to -0.70) and herd size (estimate = -0.81; 95% CI = -1.23 to -0.39) were negatively associated with TI. Specific cow breeds (Brown Swiss estimate = 1.56; 95% CI = 0.45-2.68) and Holstein Friesian (estimate = 1.42; 95% CI = 0.03-2.82; reference: other breeds) and the use of hygienic powders on the lying area (estimate = 1.10; 95% CI = 0.04-2.17) were positively associated with TI. Overall, the Swiss national reporting system is a valuable tool for AMU estimation. Several herd characteristics and management factors were associated with AMU in tiestall farms. Further studies focusing on factors associated with AMU and which are amenable to intervention will help improve stewardship programs and subsequently reduce AMU in dairy cows.

Participatory identification of the causes of antimicrobial use and how they may vary according to differences in sector structure: The case of the Flemish pork and veal sectors

The increasing threat of antimicrobial resistance (AMR) to human health has prompted many countries to adopt national action plans to reduce antimicrobial use (AMU) in farm animals. To achieve this goal, it is necessary to gain a deeper understanding of the factors driving AMU in farm animals. While previous research has focused on gaining a better understanding of AMU from the perspective of farmers and veterinarians, less emphasis has been placed on examining the systemic and contextual factors that influence AMU from multiple viewpoints within the food supply chain. To this end, this paper describes a participatory approach involving multiple stakeholders from two distinct livestock sectors to identify the underlying drivers of AMU and explore their case-specificity. For each sector, we identified causes of AMU during four online focus groups, by co-creating a “problem tree”, which resulted in the identification of over 50 technical, economic, regulatory, and sociocultural causes per sector and exploration of causal links. Following this, we analysed the focus group discussion through a content analysis and clustered causes of AMU that were related into 17 categories (i.e. main drivers of AMU), that we then classified as drivers of AMU at sector level or drivers of AMU at farm level. Finally, we compared the two sectors by assessing whether the generated categories (i.e. main drivers for AMU) had been discussed for both sectors and, if so, whether they involved the same causes and had the same implications. Through our analysis, we gained a better understanding of several main drivers of AMU at sector level, that result from systemic and/or contextual causes. As these cannot always be addressed by farmers and/or their veterinarian, we suggest that interventions should also target other actors related to these causes or consider them to help implement certain strategies. Furthermore, based on the results of our comparative analysis, we suggest that systemic structural differences, such as size and level of supply chain integration/fragmentation, may lead to differences in how animal health management is approached. This in turn may influence AMU's decision-making and the effectiveness of interventions, if they are generic and not tailored to the specificities of the sector.

One Health Approach to Antimicrobial Resistance: Integrating Human, Animal, and Environmental Perspectives

Antimicrobial resistance (AMR) is a critical global health threat that transcends human, animal, and environmental sectors, necessitating a One Health approach. AMR arises from the misuse and overuse of antimicrobial agents in clinical, veterinary, and environmental settings, resulting in treatment failures and heightened mortality rates. By 2050, AMR is projected to cause 10 million deaths annually and incur a global economic loss of 1 trillion USD. Low- and middle-income countries (LMICs) are expected to bear a significant burden, potentially accounting for 5 million of these deaths and facing substantial economic challenges due to limited access to healthcare resources and second-line antibiotics. In human health, excessive antibiotic prescriptions and hospital-acquired infections have been identified as major drivers of resistance, exacerbated by poor infection control and the lack of rapid diagnostic tools. Similarly, in veterinary medicine, the use of antimicrobials in livestock for disease prevention and growth promotion contributes significantly to AMR. Resistant bacteria from animals can transmit to humans through direct contact, the food chain, and environmental contamination. The environment further amplifies resistance through pharmaceutical waste, wastewater treatment inefficiencies, and the accumulation of resistant genes in ecosystems. Global efforts to address AMR include regulatory frameworks for prudent antimicrobial use in agriculture, human medicine, and waste management, alongside research into alternatives like phage therapy, immunotherapies, and improved diagnostics. Future solutions must focus on innovation, public engagement, and multi-sectoral collaboration to tackle the rising tide of resistance. The aim of this review is to explore the issue of Antimicrobial Resistance (AMR) from a One Health perspective, highlighting the challenges faced by low- and middle-income countries (LMICs).

Interventions to change antimicrobial use in livestock: A scoping review and an impact pathway analysis of what works, how, for whom and why.

Antimicrobial resistance (AMR) is a public health threat responsible for 700,000 deaths per year worldwide. Antimicrobial use (AMU) in livestock contributes to AMR in animal and public health. Therefore, it is essential to implement effective interventions towards better AMU in livestock. However, there is a lack of evidence to inform decision-makers of what works, how, for whom and why and how effective interventions can be adapted to different contexts. We conducted a scoping review and an impact pathway analysis to systematically map the research done in this area and to inform evidence-based and context-appropriate policies. We followed the PRISMA-ScR requirements and searched Web of Science, PubMed and Scopus databases to identify studies in English or French languages, in open access and published between 2000 and 2022. We selected thirty references addressing twenty-eight different interventions that were successful in changing AMU in livestock. We used an impact pathway logic model as an analytic framework to guide the technical aspects of the scoping review process and to identify the complex relationships between outputs, outcomes, impacts and contextual factors. A majority of interventions managed to improve AMU by changing herd and health management practices (ni=18). We identified intermediate outcomes including change in the veterinarian-farmer relationship (ni=7), in knowledge and perception (ni=6), and in motivation and confidence (ni=1). Twenty-two studies recorded positive impacts on animal health and welfare (ni=11), technical performances (ni=9), economic performances (ni=4) and AMR reduction (ni=4). Interventions implemented different strategies including herd and health management support (ni=20), norms and standards (ni=11), informational and educational measures (ni=10), economic support (ni=5). Studies were mainly in European countries and in pig and large ruminants farming. Most interventions targeted farmers or veterinarians but we identified other major and influential actors including authority and governmental organizations, academics and research, organization of producers or veterinarians, herd advisors and technicians, laboratories, and public opinion. Key success factors were knowledge and perception (ni=14), social factors (ni=13), intervention characteristics (ni=11), trajectory and ecosystem of change (ni=11), economic factors (ni=9), herd and health status (ni=8), data access and monitoring (ni=4). This review describes a paucity of impact assessment of interventions towards better AMU in livestock. There is no one-size-fits-all transition pathway but we inform decision-makers about the most successful interventions that work, how, for whom and why. The impact pathway analysis provided a holistic view of the successful change processes and the complex relationships between outputs, outcomes, impacts and contexts.

Meta-Analysis on the Global Prevalence of Tetracycline Resistance in Escherichia coli Isolated from Beef Cattle.

Antimicrobial resistance (AMR) is an emerging global concern, with the widespread use of antimicrobials in One Health contributing significantly to this phenomenon. Among various antimicrobials, tetracyclines are extensively used in the beef cattle industry, potentially contributing to the development of resistance in bacterial populations. This meta-analysis aimed to examine the association between tetracycline use in beef cattle and the development of tetracycline resistance in Escherichia coli isolates. A comprehensive search was conducted using multiple databases to gather relevant observational studies evaluating tetracycline use and tetracycline resistance in Escherichia coli isolates from beef cattle. The rate of tetracycline resistance from each study served as the effect measure and was pooled using a random-effects model, considering possible disparities among studies. The meta-analysis of 14 prospective longitudinal studies resulted in a 0.31 prevalence of tetracycline resistance in Escherichia coli in non-intervention (no exposure), contrasting numerically elevated resistance rates in the intervention (exposed) groups of 0.53 and 0.39 in those receiving tetracyclines via feed or systemically, respectively. Despite the observed numerical differences, no statistically significant differences existed between intervention and non-intervention groups, challenging the conventional belief that antimicrobial use in livestock inherently leads to increased AMR. The findings of this study underscore the need for additional research to fully understand the complex relationship between antimicrobial use and AMR development. A considerable degree of heterogeneity across studies, potentially driven by variations in study design and diverse presentation of results, indicates the intricate and complex nature of AMR development. Further research with standardized methodologies might help elucidate the relationship between tetracycline use and resistance in Escherichia coli isolated from beef cattle.

Antimicrobial Consumption in the Livestock Sector in Bhutan: Volumes, Values, Rates, and Trends for the Period 2017–2021

Data on the use of antimicrobials in humans and livestock may provide evidence to guide policy changes to mitigate the risk of antimicrobial resistance (AMR). However, there is limited information available about antimicrobial use in livestock in low- and middle-income countries, even though these nations are most vulnerable to the impact of AMR. This study aimed to assess the consumption of veterinary antimicrobials in Bhutan and identify areas for improvement to reduce the use of antimicrobials in livestock. National data on livestock numbers and annual procurement of veterinary antimicrobials over five years (2017-2021) were used to calculate rates of antimicrobial consumption and annual national expenditure on veterinary antimicrobials in Bhutan. The rate of antimicrobial consumption in Bhutan was 3.83 mg per population correction unit, which is lower than most countries in Europe, comparable with the rates of consumption in Iceland and Norway, and approximately 120-fold lower than published rates of antimicrobial consumption in South Asian countries, including Nepal and Pakistan. The low rates of antimicrobial consumption by the animal health sector in Bhutan could be attributable to stronger governance of antimicrobial use in Bhutan, higher levels of compliance with regulation, and better adherence to standard guidelines for antimicrobial treatment of livestock.

Assessment of the knowledge and behavior of backyard and small-scale producers in California regarding disease prevention, biosecurity practices and antibiotics use.

The number and popularity of backyard poultry and livestock farming have rapidly increased in California as well as other states in the United States following consumers' preference for local and organic products in the last few years. This study aimed to investigate current on-farm management and farmers' understanding of Veterinary Feed Directive (VFD) and California Senate Bill (SB) 27 implications for disease prevention, biosecurity procedures, and antimicrobial use in small-scale and backyard farms in California. The survey consisted of 38 questions. The responses of 242 backyard and small-scale livestock owners were investigated in this study. Descriptive statistics summarized survey responses, and multivariable logistic regression evaluated the association of antibiotics purchase and use, and the impact of VFD and SB27 on antibiotic use with demographics and on-farm management. Backyard and small-scale farmers in California mostly raised chickens or small ruminants with small herd sizes kept for personal use. Antibiotics were generally used for individual treatment of a sick animal with the guidance of a veterinarian. VFD and SB27 implementation promoted the judicious use of antibiotics, specifically, by enhancing the relationship between backyard and small-scale farmers with veterinarians and treating fewer animals with antibiotics under veterinary oversight. Therefore, better access to veterinary service in backyard and small-scale farms will improve the farmer's knowledge of good husbandry practices with judicious antimicrobial use in livestock and finally contribute to reducing the risk of antimicrobial resistance in California.

A participatory approach for building ex ante impact pathways towards a prudent use of antimicrobials in pig and poultry sectors in France.

Antimicrobial resistance (AMR) is a global public health threat responsible for 700,000 deaths per year worldwide. There is scientific evidence of the causal relationship between antimicrobial use (AMU) along the food chain and AMR. Improving AMU in livestock is therefore a key component in the fight against AMR. To improve AMU in livestock, there is no one-size-fits-all solution and strategies must be context-adapted and socially acceptable for actors in order to increase AMU sustainability. AMU decision-making is based on an interdependent set of economic, behavioral, ethical, and cultural factors that need to be assessed to advise on the potential impacts of measures. We hypothesized that a participatory strategic planning approach may increase the plausibility and the efficacy of the strategies formulated by facilitating the dialogue between actors of diverse backgrounds, stimulating innovative thinking and constant considerations of contextual factors, actors and impacts. We adapted and applied the ImpresS ex ante approach (IMPact in reSearch in the South, https://impress-impact-recherche.cirad.fr/) within a Living Lab engaging actors from the French pig and poultry sectors in co-creation of innovative strategies towards improved AMU. We conducted semi-structured interviews and participatory workshops between April 2021 and March 2022. The results describe 1) an initial diagnosis of the current AMU situation in the pig and poultry sectors in France; 2) a common vision of the future to which participants would like to contribute through the intervention; 3) an identification of the current problems opposed to this vision of the future; 4) a defined scope of the intervention; 5) a typology of actors protagonist or impacted by those issues and 6) outcome maps to solve a priority problem related to indicators and monitoring. This study provides recommendations for decision-makers on plausible and innovative strategies to sustainably improve AMU in pig and poultry sectors in France and evidence of the benefits of participatory strategic planning approaches.

Factors Associated with Antimicrobial Use in Fijian Livestock Farms.

Antimicrobial stewardship (AMS) programmes in human health and livestock production are vital to tackling antimicrobial resistance (AMR). Data on antimicrobial use (AMU), resistance, and drivers for AMU in livestock are needed to inform AMS efforts. However, such data are limited in Fiji. Therefore, this study aimed to evaluate the association between farmer (socio-economic, demographic) and livestock production and management factors with AMU. Information was collected using purposive and snowball sampling from 236 livestock farmers and managers located in Central and Western divisions, Viti Levu, Fiji. Multinomial logistic regression was used to determine the factors associated with AMU in farms using an aggregated livestock farm model. Farms that raised cattle only for dairy (farm factor) were more likely to use antibiotics and anthelmintics (p = 0.018, OR = 22.97, CI 1.713, 308.075) compared to mixed cattle and poultry farms. Farms that maintained AMU records were more likely to use antibiotics (p = 0.045, OR = 2.65, CI 1.024, 6.877) compared to farms that did not. Other livestock production and management factors had no influence on AMU on the livestock farms. AMU in livestock farms was not influenced by the socio-economic and demographic characteristics of the farmer. There were differences between livestock enterprises regarding their management. The lack of association between management system and AMU could be because there was so much variation in management system, levels of farmer knowledge and awareness of AMU, and in management of farm biosecurity. Future studies exploring farmers’ knowledge and awareness of AMU and livestock management are required to design AMS programmes promoting prudent AMU in all livestock farms locally.

Cross-Sectional Survey of Prophylactic and Metaphylactic Antimicrobial Use in Layer Poultry Farming in Cameroon: A Quantitative Pilot Study.

An evaluation of the patterns of antimicrobial use in livestock can help understand the increasing level of antimicrobial resistance worldwide. This study aimed at evaluating antimicrobial usage in modern layer poultry farms in the West Region of Cameroon. In this light, 70 layer poultry farms and 4 veterinary pharmacies were surveyed. Data on antimicrobial use were collected through interviews using a quantitative-frequency questionnaire and consultation of medical records. The four veterinary pharmacies sold a total of 2.8 tons of antimicrobials (active ingredients) during 2011. At the level of farms, 297 kg of antimicrobials (active ingredients) were used in the 50 layer poultry farms surveyed. Tetracycline, sulfonamides, quinolones, and β-lactams (aminopenicillins) were the most sold and used drugs in layer farms. As for treatment indication, metaphylactic (58.1%) and prophylactic (41.9%) treatments were the most observed practices, and nearly all (99%) treatments were administered per os as remedies to respiratory (33.4%) and digestive (24.7%) tract symptoms. Overall, 78.2% of antimicrobials sold in pharmacies and 67.3% used in the farms belonged to the class of critically important antimicrobials of the WHO categorization of antimicrobials according to their importance to human medicine. Doxycycline, sulfonamide, ampicillin, and streptomycin, which have been banned for layer poultry in the production of eggs for human consumption, were still used in Cameroon. The treatment incidences based on the used daily dose (TIUDD) and animal daily dose (TIADD) were 11.59 and 10.45, respectively. In regard to dosage correctness based on the UDD/ADD ratio, aminoglycosides (100%), macrolides (90.6%), and tetracyclines (74.5%) were the most underdosed, while trimethoprim sulfonamides (45.8%) and β-lactams (35.7%) were overdosed. This study highlights an irrational antimicrobial usage in layer poultry farms. Regulation of the use of antimicrobials and the education of farmers on adequate antimicrobial use are essential to preserve the effectiveness of drugs in both humans and animals.

Antimicrobial resistance and population genomics of multidrug-resistant Escherichia coli in pig farms in mainland China

The expanding use of antimicrobials in livestock is an important contributor to the worldwide rapid increase in antimicrobial resistance (AMR). However, large-scale studies on AMR in livestock remain scarce. Here, we report findings from surveillance of E. coli AMR in pig farms in China in 2018–2019. We isolated E. coli in 1,871 samples from pigs and their breeding environments, and found AMR in E. coli in all provinces in mainland China. We detected multidrug-resistance in 91% isolates and found resistance to last-resort drugs including colistin, carbapenems and tigecycline. We also identified a heterogeneous group of O-serogroups and sequence types among the multidrug-resistant isolates. These isolates harbored multiple resistance genes, virulence factor-encoding genes, and putative plasmids. Our data will help to understand the current AMR profiles of pigs and provide a reference for AMR control policy formulation for livestock in China.

Distinct increase in antimicrobial resistance genes among Escherichia coli during 50 years of antimicrobial use in livestock production in China.

Antimicrobial use in livestock production is linked to the emergence and spread of antimicrobial resistance (AMR), but large-scale studies on AMR changes in livestock isolates remain scarce. Here we applied whole-genome sequence analysis to 982 animal-derived Escherichia coli samples collected in China from the 1970s to 2019, finding that the number of AMR genes (ARGs) per isolate doubled-including those conferring resistance to critically important agents for both veterinary (florfenicol and norfloxacin) and human medicine (colistin, cephalosporins and meropenem). Plasmids of incompatibility groups IncC, IncHI2, IncK, IncI and IncX increased distinctly in the past 50 years, acting as highly effective vehicles for ARG spread. Using antimicrobials of the same class, or even unrelated classes, may co-select for mobile genetic elements carrying multiple co-existing ARGs. Prohibiting or strictly curtailing antimicrobial use in livestock is therefore urgently needed to reduce the growing threat from AMR.

Danish cattle veterinarians' perspectives on antimicrobial use: Contextual and individual influencing factors

The global risk for antimicrobial resistance (AMR) can be reduced by reducing antimicrobial use (AMU). Veterinarians are one of the key actors in relation to AMU in livestock, and understanding the dynamics of veterinary treatment and prescription is central to achieving AMU reduction. Veterinary AMU decisions are influenced by a complex pattern of both individual and contextual factors. In this study, we conducted semi-structured interviews with 16 Danish cattle veterinarians to investigate their perspectives on AMU and current practices in a national context with low use and extensive legal control. We found that personal experiences and emotions, rather than scientific evidence, guided some veterinarians when making AMU choices. Furthermore, less-experienced veterinarians felt pressure to prescribe according to colleagues' and farmers' preferences for certain antimicrobials. We found that changes in Danish legislation seemed to have introduced hesitancy and a lack of motivation within the veterinary profession, and that AMR was perceived as an abstract threat not applicable to the veterinarians' daily professional decision making. We concluded that the lack of field-generated research of local relevance nourished a culture in which AMU choices are built on personal experience rather than scientific evidence, which also diminished newly educated veterinarians' self-confidence in relation to their AMU choices. Future research should focus on developing locally relevant research on optimal AMU choices and AMR, and the implications of extensive legal control of AMU in livestock farming should be further investigated to find a balance on the path to reducing AMU.

Knowledge, Attitudes, and Practices of Antimicrobial Use and Resistance among Livestock Producers in Cambodia

The development of antimicrobial resistance (AMR) due to over or misuse of antibiotics/antimicrobials is a globally increasing public health concern. This study was conducted to assess the current knowledge, attitudes, and practices (KAP) of swine and poultry producers on antimicrobial use (AMU) and antimicrobial resistance (AMR). A total of 254 swine and poultry producers of 5 provinces in Cambodia were purposively surveyed using validated KAP questionnaires, a useful tool for promoting the rational use of antimicrobials in livestock. Collectively, this study found out that livestock producers in Cambodia have a low level of knowledge, neutral rather than positive attitudes, and employed poor practices on the AMU and AMR. Thus, there is a need to promote among producers the rational and responsible use of antimicrobials. Furthermore, public awareness of the AMR implications on public health can contribute to the prevention or reduction of AMU and AMR in Cambodia.