Antibiotics: practice and opinions of Cambodian commercial farmers, animal feed retailers and veterinarians

Consumers' perspectives on antibiotic use and antibiotic resistance in food animals: a systematic review

Inappropriate antibiotic use in food animals is considered a significant contributor to increasing antibiotic resistance. Consumers can play a critical role in reducing it through purchasing choices, demand, and policy advocacy. This systematic review aimed to synthesize all published literature investigating consumers' perspectives (i.e., knowledge, perceptions, and attitudes) on antibiotic use and antibiotic resistance in food animals. We conducted a comprehensive literature search in PubMed, Web of Science, Scopus, and Google Scholar on November 14, 2022, and an updated search on April 30, 2024. We limited findings to original peer-reviewed journal articles published up to 2023 (inclusive), were written in English, and focused on knowledge/perceptions/attitudes of antibiotic use and antibiotic resistance in food animals. Of the 3815 articles identified, 39 were included. The findings suggested that consumers were concerned about antibiotic use in food animals, thus they were willing to pay more for food products with antibiotic-free or reduced-antibiotic use. However, consumers lacked deep understanding of antibiotic use practice and antibiotic stewardship in food animals as well as transmission risks of antibiotic-resistant bacteria. These findings offer valuable insights for policymakers and livestock industries to implement policy and practice changes to ensure responsible antibiotic use in food animals.

Genomic insights into extended-spectrum β-lactamase- and plasmid-borne AmpC-producing Escherichia coli transmission between humans and livestock in rural Cambodia

Introduction. The global spread of extended-spectrum cephalosporinase-producing Escherichia coli (producing extended-spectrum β-lactamase or plasmid-borne AmpC, hereafter ESC-Ec) is a major public health concern. Whilst extensively studied in high-income countries, the transmission pathways between humans and animals in low- and middle-income countries (LMICs) remain unclear. In rural Cambodia, the asymptomatic carriage and transmission dynamics of ESC-Ec between humans and animals living in close proximity are poorly understood, highlighting the need for targeted research in this area.Gap statement. An enhanced understanding of the genetic epidemiology of ESC-Ec can enable mitigation strategies to reduce the burden of disease and drug-resistant infections in LMIC settings.Aim. This study aimed to investigate the genetic relatedness and genotypic antibiotic resistance profiles of ESC-Ec strains from humans and livestock in rural Cambodia and to identify patterns of antimicrobial resistance (AMR) gene transmission between hosts and across households and villages.Methodology. Faecal samples were collected from 307 humans and 285 livestock in 100 households in or near Kampong Cham Province in rural Cambodia. From these samples, 108 ESC-Ec strains were subjected to whole-genome sequencing. Core genome MLST (cgMLST) and phylogenetic analysis determined genetic relationships between strains. All strains were screened for the presence of antibiotic resistance genes and plasmids.Results. Human and livestock isolates were assigned to six phylogroups, with phylogroup A being the most common (56.5%). MLST identified 50 sequence types (STs), 17 of which were shared between humans and animals, with ST155 being the most prevalent. cgMLST revealed 97 distinct cgMLST sequence types (cgST), indicating strain sharing between humans and animals. Additionally, AMR gene analysis showed widespread resistance, with genes from the bla CTX-M group detected in 84.2% of isolates. Notably, AMR genes such as aph(3'')-Ib-sul2 co-occurred in 50% of isolates. Finally, plasmid analysis identified IncF plasmids in 75.9% of isolates, likely facilitating AMR gene transmission across hosts.Conclusions. Our findings demonstrate that ESC-Ec strains and their AMR genes are transmitted between humans and livestock in rural Cambodia, likely driven by both clonal spread and plasmid-mediated horizontal gene transfer. These results highlight the urgent need for antimicrobial stewardship and infection control strategies to mitigate the spread of multidrug-resistant pathogens in both human and animal populations.

Genomic Diversity and Potential Transmission and Persistence of Salmonella in the Cambodian Vegetable Supply Chain

S. enterica isolates (n = 78) obtained from the vegetable supply chain (farms, distribution centers, markets) in two Cambodian provinces (Siem Reap, Battambang) were sequenced and analyzed. In silico identification of serotypes and detection of antimicrobial resistance genes was performed using SISTR and ABRicate, respectively. Isolates' relatedness was assessed based on high-quality single nucleotide polymorphisms (hqSNPs) identified within each serotype using the CFSAN SNP pipeline. Among 29 detected serotypes, Paratyphi B var. Java was most abundant (n = 14), followed by Hvittingfoss (n = 11) and Thompson (n = 7). Paratyphi B var. Java was mostly found in farms (n = 5) and markets (n = 6), Hvittingfoss within distribution centers (n = 8), and Thompson at markets (n = 4) and farms (n = 3). Among Paratyphi B var. Java isolates, one phylogenetic clade contained four closely related isolates (0-1 SNP difference), collected at markets in different provinces on different days. Another clade contained two isolates that differed by one SNP, one obtained from a Battambang farm and one from a Siem Reap distribution center, suggesting a broad spread of Paratyphi B var. Java in the Cambodian vegetable supply chain. Hvittingfoss isolates clustered in two clades; one contained five identical isolates, four of which were obtained in different months from the distribution center and a farm in Battambang, suggesting possible transmission among supply chain stages. The second clade contained three isolates from the Battambang distribution center that differed by 0-1 SNP and were isolated in October and November, indicating possible persistence. Lastly, among 78 analyzed isolates, 14 carried antimicrobial resistance genes and seven out of these 14 carried genes with predicted resistance to more than three classes of antibiotics. Overall, highly similar isolates of Salmonella were identified over time and at different supply chain stages, suggesting possible persistence and transmission of Salmonella within and between supply chain stages.

Antimicrobial use in animal farms in Egypt: rates, patterns, and determinants

BACKGROUND

While antimicrobial use (AMU) in human healthcare has received significant attention as a key driver of antimicrobial resistance (AMR), less emphasis has been placed on AMU practices and attitudes in animal husbandry. To address this gap, this study examines the patterns and underlying drivers of AMU on animal farms.

METHODS

A survey instrument was distributed to farm staff in 150 animal farms across 15 Egyptian governorates. Farms were selected from a list curated by a private platform specialized in Egypt's poultry and cattle industry. An online search was conducted to identify additional farms not included in the list or when the contact information was unavailable. The instrument covered key items related to AMU including types of antimicrobials used, indications, their perceived benefits, and the feed conversion ratio (FCR). Using the theory of reasoned action (TRA) as a guiding theoretical framework, this study assesses key factors influencing the AMU behavior of farm personnel.

RESULTS

Out of 150 farm personnel invited to fill out the survey forms, 111 (74%) responded and agreed to participate. All surveyed personnel reported using antimicrobials, and almost two-thirds (65%) reported using them for non-therapeutic purposes. Non-therapeutic use of antimicrobials, however, had no impact on FCR across all farm types (poultry, cattle, and mixed). The most used antimicrobials were penicillins (81%), followed by macrolides (78%) and tetracyclines (72%). Half of the studied farms reported using colistin, with more than half of this segment (55%) reporting using it for non-therapeutic purposes. Farm personnel's AMU behavior was associated with the TRA constructs: perceived benefits of antimicrobials (attitude) and perceived AMU behavior in other farms (subjective norm).

CONCLUSIONS

Antimicrobials are unanimously used in animal farms in Egypt, including those classified as last-resort options, such as colistin. Using antimicrobials for disease prevention or growth promotion did not decrease the FCR. Interventions that target the farm personnel's attitude and the subjective norm should be carried out to change their behavior regarding the use of antimicrobials. Egyptian guidelines for AMU in livestock are urgently needed, along with training to raise awareness of AMR and safer practices. The use of last-resort drugs like colistin should be banned in animal farming, and national surveillance systems should monitor AMU and AMR trends.

Biological Hazards and Indicators Found in Products of Animal Origin in Cambodia from 2000 to 2022: A Systematic Review

Biological hazards in products of animal origin pose a significant threat to human health. In Cambodia, there are few comprehensive data and information on the causes of foodborne diseases or risks. To date, there has been no known published study similar to this review. This systematic review is aimed to investigate the prevalence of biological hazards and their indicators in products of animal origin from 2000 to 2022. The main objective of this study was also to contribute to strengthening Cambodia's food control system. This review followed the established "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA) guidelines. In total, 46 studies were retained for complete review. Most studies (n = 40) had been conducted by or with external researchers, reflecting the under-resourcing of the National Food Control System in terms of surveillance; areas outside the capital were relatively understudied, reflecting evidence found in Ethiopia and Burkina Faso. Five categories of hazards were reported with the highest number of studies on fish parasites. Marketed fish, often originating from different countries, had a higher mean value of parasite prevalence (58.85%) than wild-caught fish (16.46%). Viral pathogens in bat meat presented a potential spillover risk. Many potentially important hazards had not yet been studied or reported (e.g., Norovirus, Shigella, toxin-producing Escherichia coli, and Vibrio cholerae). The findings of our review highlighted significant urgencies for national competent authorities to enhance food hygiene practices along the production chain, tackle import control, and enforce the implementation of a traceability system, alongside more research collaboration with neighboring countries and key trading partners. It is crucial to conduct more extensive research on food safety risk analysis, focusing on the identification and understanding of various biological hazards and their associated risk factors in food.

Understanding Consumers' Purchase Intention Towards Meat Produced Without Preventive Antibiotic Use

Antibiotics are widely used to prevent healthy animals from getting diseases in livestock industries. Such practice has greatly contributed to the increase in antibiotic-resistant pathogens in animals and in the environment, which poses severe health threats to humans. This study aims to investigate consumers' purchase intention towards meat produced without preventive antibiotic use, and to identify key factors influencing this purchase intention. An online survey of 1123 participants was conducted in China. Descriptive statistical analysis, correlation, and regression analysis were conducted. The results suggested that consumers had a negative attitude towards preventive antibiotic use in food animals and a strong purchase intention towards meat produced without it. The key drivers of this purchase intention included health consciousness, trust in responsible antibiotic use in farming, objective knowledge about antibiotics used in food animals, subjective knowledge about preventive antibiotic use, concerns over antibiotic residues, and attitude towards preventive antibiotic use. These findings can provide deep insights for policymakers and livestock industries who seek to promote responsible antibiotic use and develop effective communication strategies with consumers.

Colistin resistance in ESBL- and Carbapenemase-producing Escherichia coli and Klebsiella pneumoniae clinical isolates in Cambodia

OBJECTIVES

Despite the critical importance of colistin as a last-resort antibiotic, limited studies have investigated colistin resistance in human infections in Cambodia. This study aimed to investigate the colistin resistance and its molecular determinants among Extended-spectrum beta-lactamase (ESBL)- and carbapenemase-producing (CP) Klebsiella pneumoniae (K. pneumoniae) and Escherichia coli (E. coli) isolated in Cambodia between 2016 and 2020.

METHODS

E. coli (n = 223) and K. pneumoniae (n = 39) were tested for colistin minimum inhibitory concentration (MIC) by broth microdilution. Resistant isolates were subjected to polymerase chain reaction (PCR) for detection of mobile colistin resistance genes (mcr) and chromosomal mutations in the two-component system (TCS).

RESULTS

Eighteen isolates (10 K. pneumoniae and 8 E. coli) revealed colistin resistance with a rate of 5.9% in E. coli and 34.8% in K. pneumoniae among ESBL isolates, and 1% in E. coli and 12.5% in K. pneumoniae among CP isolates. The resistance was associated with mcr variants (13/18 isolates, mcr-1, mcr-3, and mcr-8.2) and TCS mutations within E. coli and K. pneumoniae, with the first detection of mcr-8.2 in Cambodia, the discovery of new mutations potentially associated to colistin resistance in the TCS of E. coli (PhoP I47V, PhoQ N352K, PmrB G19R, and PmrD G85R) and the co-occurrence of mcr genes and colistin resistance conferring TCS mutations in 11 of 18 isolates.

CONCLUSIONS

The findings highlight the presence of colistin resistance in ESBL- and CP- Enterobacteriaceae involved in human infections in Cambodia as well as chromosomal mutations in TCS and the emergence of mcr-8.2 in E. coli and K. pneumoniae. It underscores the need for continuous surveillance, antimicrobial stewardship, and control measures to mitigate the spread of colistin resistance.

The effect of information provision on consumers' risk perceptions of, support for a ban, and behavioral intention towards the preventive use of antibiotics in food animals

BACKGROUND

Antibiotics have been widely used in feed and drinking water for food animals to prevent them from getting sick. Such preventive use of antibiotics has become a contributor to increasing antibiotic resistance and thus poses threats to human health. However, consumers have little knowledge about this practice and the associated health risks of increasing transmission of antibiotic residues and antibiotic resistant bacteria. This study aimed to examine the effect of information provision on consumers' risk perceptions, support for a ban, and behavioral intention regarding the preventive use of antibiotics in food animals. Especially, the study sought to test two competing hypotheses which were informed by two theoretical perspectives of fear appeal theory - the linear model and the plateau effect model. The former suggested that providing information on the health risks of both antibiotic residues and antibiotic resistant bacteria would have a stronger effect compared to providing information on only one of them, while the latter posited that providing information on both risks might not have additional influence, as the effect of information on either risk could reach the plateau.

METHODS

An experimental study with four conditions was conducted where participants read different information on the health risks associated with the preventive use first and then answered questions regarding consumers' risk perceptions, support for a ban, and behavioral intention regarding the preventive use. Condition 1 was the control condition, where basic information about antibiotics, antibiotic resistance, and the preventive use was provided. Condition 2 and Condition 3 further added information on the health risk of antibiotic residues (Condition 2) and antibiotic resistant bacteria (Condition 3) due to the preventive use, respectively. Condition 4 provided all information contained in the first three conditions.

RESULTS

The results showed that compared to participants in the control condition, participants in Conditions 2-4 reported higher risk perceptions, stronger support for a ban on the preventive use, and a higher intention to buy meat produced without the preventive use of antibiotics. However, there were no significant differences in these factors between Conditions 2-4, indicating that providing information on the health risk of either antibiotic residues, or antibiotic resistant bacteria, or both, has similar effect on these variables. That is, the hypothesis based on the plateau effect model was supported.

CONCLUSIONS

The findings suggested that informing the public with the health risk of either antibiotic residues or antibiotic resistant bacteria associated with the preventive use is effective enough to reach plateau effect in increasing risk perceptions, support for a ban, and behavioral intention, which has important implications for policymakers and livestock industries to develop effective communication strategies to promote responsible antibiotic use in food animals.

Antimicrobial stewardship in private pharmacies in Wakiso district, Uganda: a qualitative study

BACKGROUND

Private pharmacies are the first point of contact for the public regarding acquisition of medicines and other pharmaceuticals in many low- and middle-income countries including Uganda. Most antimicrobial stewardship (AMS) programmes in Uganda have targeted pharmacies in public health facilities, with little known about private pharmacies. This study explored knowledge and practices related to AMS in private pharmacies in Wakiso district, central Uganda.

METHODS

This was a qualitative study that involved 31 in-depth interviews to explore AMS among retail private pharmacy staff including pharmacists, pharmacy technicians/dispensers, and nurses. Participants were asked about antimicrobial resistance (AMR) and AMS practices at their pharmacy. The audio-recorded interviews were transcribed verbatim and imported to NVivo 2020 (QSR International) for thematic analysis.

RESULTS

Five major themes emerged from the study: commonly sold antimicrobials; knowledge on AMR and AMS; potential contributors to AMR; practices related to AMS; and challenges to AMS. The commonly sold antimicrobials in the pharmacies with or without prescriptions were oral azithromycin, Ampiclox® (ampicillin and cloxacillin), amoxicillin, ciprofloxacin, Septrin® (co-trimoxazole), metronidazole, Flucamox® (amoxicillin and flucloxacillin), Augmentin® (amoxicillin and clavulanic acid), cephalexin, doxycycline, and chloramphenicol. Participants had heard about AMR but not AMS, although only a few correctly defined AMR. Lack of knowledge among health workers and local communities; the overuse, misuse, and abuse of antimicrobials such as non-adherence to dosage; self-medication; and purchase of drugs without prescription were identified as potential accelerators to the emergence of AMR. Current practices related to AMS in private pharmacies were limited to meetings, antimicrobial dispensing, providing client advice, record keeping, and monitoring of drugs. Cost of healthcare, client satisfaction and retention, outdated guidelines, and the business orientation of pharmacies were the main challenges related to AMS.

CONCLUSION

There was poor knowledge of AMR and AMS, and limited AMS practices in private pharmacies. Private pharmacies have the potential to contribute to Uganda's fight against AMR if motivated and equipped with adequate knowledge to enhance their practices related to AMS.

"It's a habit. They've been doing it for decades and they feel good and safe.": A qualitative study of barriers and opportunities to changing antimicrobial use in the Indonesian poultry sector

Interventions to change antimicrobial use (AMU) practices can help mitigate the risk of antimicrobial resistance (AMR) development. However, changing AMU practices can be challenging due to the complex nature of the factors influencing AMU-related behaviours. This study used a qualitative approach to explore the factors that influenced decision-making on AMU by farmers and other actors in the Indonesian poultry sector. Thirty-five semi-structured interviews were conducted with farmers, technical services staff from the private sector, and representatives of associations, universities, and international organisations in Central Java, West Java, and East Java. Thematic analysis identified three patterns of influence on AMU: how farmers used information to make AMU-related decisions, the importance of farmers' social and advisory networks, and the motivations driving changes in AMU behaviours. Key barriers identified included a lack of shared understanding around when to use antibiotics, financial pressures in the poultry sector, and a lack of engagement with government veterinary services. Potential opportunities identified included high farmer awareness of AMU, identification of private sector actors and peer networks as the stakeholders with established relationships of trust with farmers, and the importance of farmers' conceptions of good farming practices, which could be engaged with to improve AMU practices.

Knowledge and practice of antimicrobial usage and resistance among poultry farmers: A systematic review, meta-analysis, and meta-regression

A systematic review was conducted to summarize and synthesize the existing research on poultry farmers' knowledge, practices, and awareness regarding antimicrobial use (AMU) and antimicrobial resistance (AMR). It was undertaken by systematically searching databases, screening and characterizing relevant studies, extracting data, and evaluating the risk of bias. The outcomes were stratified into several subgroups, and pooled prevalence of each subgroup was calculated using a random-effect meta-analysis. Meta-regression was used for selected outcomes to further investigate the potential sources of heterogeneity across studies. Poultry farmers had knowledge and practice gaps on antimicrobial use. While most (65%; 95% CI: 50%-80%) used antimicrobials on poultry for therapeutic purposes, a portion used them to prevent disease (45%; 95% CI: 34%-55%) or boost growth (29%; 95% CI: 13%-46%) and productivity (20%; 95% CI: 6%-34%). 60% (95% CI: 50%-69%) of farmers approached veterinarians for antimicrobial advice, although many consulted drug sellers and fellow farmers. Insufficient antimicrobial residue knowledge (45%; 95% CI: 29%-62%), as well as inadequate awareness and faulty practice on withdrawal periods, were identified. Only 43% (95% CI: 34%-53%) were knowledgeable about AMR. Around half of farmers understood AMR's impacts on poultry, human health, and the environment. Meta-regression demonstrated that the source of heterogeneity for therapeutic antimicrobial use was the type of poultry farmers sampled and their educational qualifications; geographical region was significantly associated with antimicrobial usage based on farmers' experience; and the country's economic state was correlated with farmers' understanding of antimicrobial residue. This study recommends implementing legislation for judicious antimicrobial use, and farmer awareness campaigns to reinforce knowledge about prudent AMU and AMR.

Underestimated economic and social burdens of non-Typhoidal Salmonella infections: The One Health perspective from Nigeria

Background

The non-typhoidal salmonellosis (NTS) is a pathogenic bacterial zoonosis with substantial but often under-appreciated public health impacts. The NTS is prevalent in poultry and humans in Nigeria, yet its economic and social burden have not been determined through any empirical study. To bridge the gap, we evaluated the impact of NTS in social and economic terms.

Methods

Relevant population, economic and epidemiological data were retrieved from peer-reviewed publications, open sources and relevant authorities. Additional data were obtained through experts' opinions and field surveys. Using a customized and validated Microsoft Excel® tool, economic analysis was conducted.

Results

Using the year 2020 reference point, the burden of NTS was 325,731 cases and a total of 1043 human deaths, at a disability-adjusted life year (DALYs) of 37,321. The cost associated with infection in humans was US$ 473,982,068. A total loss of US$ 456,905,311 was estimated in poultry including the direct value of animal loss, US$ 224,236,769, loss from salvage slaughter and culling, US$ 220,386,556, and value of foregone production, US$ 12,281,987.

Interpretation

The outcomes of this important work provide empirical evidence to support informed decisions and investments in the control and eradication of human and poultry salmonellosis (NTS) in Nigeria.

Influx of Backyard Farming with Limited Biosecurity Due to the COVID-19 Pandemic Carries an Increased Risk of Zoonotic Spillover in Cambodia

Backyard farming with limited biosecurity creates a massive potential for zoonotic spillover. Cambodia, a developing nation in Southeast Asia, is a hub for emerging and endemic infectious diseases. Due to pandemic-induced job losses in the tourism sector, rumors suggest that many former Cambodian tour guides have turned to backyard farming as a source of income and food security. A cross-sectional study including 331 tour guides and 69 poultry farmers in Cambodia before and during the novel coronavirus disease 2019 (COVID-19) pandemic was conducted. Participants were administered a survey to assess food security, income, and general farming practices. Survey data were collected to evaluate the risk perceptions for avian influenza virus (AIV), antimicrobial resistance (AMR), and general biosecurity management implemented on these poultry farms. Overall, food security decreased for 80.1% of the tour guides during the COVID-19 pandemic. Approximately 21% of the tour guides interviewed used backyard poultry farming to supplement losses of income and food insecurity during the COVID-19 pandemic, with a significantly higher risk than for traditional poultry farmers. Agricultural intensification in Cambodia due to the COVID-19 pandemic has caused an influx of makeshift farms with limited biosecurity. Inadequate biosecurity measures in animal farms can facilitate spillover and contribute to future pandemics. Improved biosecurity and robust viral surveillance systems are critical for reducing the risk of spillover from backyard farms. IMPORTANCE While this study highlights COVID-19-associated changes in poultry production at a small scale in Cambodia, poultry production is expected to expand due to an increase in the global demand for poultry protein during the pandemic, changes in urbanization, and the reduction of the global pork supply caused by African swine fever (ASF). The global demand and surge in poultry products, combined with inadequate biosecurity methods, can lead to an increased risk of domestic animal and human spillovers of zoonotic pathogens such as avian influenza. Countries in regions of endemicity are often plagued by complex emergency situations (i.e., food insecurity and economic fallouts) that hinder efforts to effectively address the emergence (or reemergence) of zoonotic diseases. Thus, novel surveillance strategies for endemic and emerging infectious diseases require robust surveillance systems and biosecurity training programs to prevent future global pandemics.

Knowledge, Attitudes, and Practices Related to Antibiotic Use and Antibiotic Resistance among Poultry Farmers in Urban and Peri-Urban Areas of Ouagadougou, Burkina Faso

Increased use of antibiotics in livestock is a public health concern, as it poses risks of antibiotic residues and antibiotic-resistant pathogens entering the food chains and infecting humans. A cross-sectional survey was conducted on 216 poultry farms to study knowledge, attitudes and practices of poultry farmers on the use of antibiotics in urban and peri-urban areas of Ouagadougou. Results show that only 17.13% (37/216) of farmers attended training on poultry production. Majority of farmers-85.65% (185/216) were not knowledgeable about the rational use of antibiotics. When there was a disease outbreak, 31.98% (63/197) of farmers used veterinary drugs without a prescription and 22.34% (44/197) consulted a community animal health worker. It should also be noted that 79.19% (156/197) of farmers reported using chicken meat as per normal if the bird died during or right after treatment with an antibiotic. Knowledge of rational use of antibiotics was positively influenced by a good attitude adopted by the farmer during the illness of birds and negatively influenced by disease treatment success and high level of education of the farmer. Lack of knowledge about the rational use of antibiotics including their use without a prescription are serious risk factors for the emergence of antimicrobial resistance. Awareness of farmers and other veterinary drug supply chain actors such as drug stockists and animal health workers on best practices in antimicrobial use and promotion of good biosecurity on farms are important to reduce the misuse of antibiotics.

Antibiotic use by poultry farmers in Kiambu County, Kenya: exploring practices and drivers of potential overuse

BACKGROUND

Antibiotic resistance is a global concern threatening achievements in health care since the discovery of antibiotics. In Kenya, this topic remains understudied in a context of rising demand for livestock products, intensification and the concomitant increase in antibiotic use. Our study investigates drivers and practices of antibiotic use in poultry farming. The study was conducted in Kiambu County, Kenya.

METHODS

A qualitative research methodology was employed: fourteen key informant interviews, twenty in-depth interviews, and four focus group discussions were undertaken. The interviews were semi-structured. Themes and subthemes from the interviews were generated through inductive analysis.

FINDINGS

Of the farmers interviewed, sixty eight percent were female, thirty three percent of the sampled farmers could not read, and the majority (eight five percent) of farmers had reared poultry for at least ten years. Research findings showed that farmers extensively used antibiotics. Antibiotic use was influenced by factors such as high disease burden, access to medicines and economic pressure. Common practices included prophylactic use, use of antibiotics to enhance production, self-prescription use, use of combination antibiotics (A combination antibiotic is one in which two or more antibiotics are added together for additional therapeutic effect.), and antibiotics classified as critically important in human medicine. Key information sources for the farmers were agro- veterinary dispensers, sellers of day-old chicks, and peer-learning. External factors driving the inappropriate use of antibiotics included access to the antibiotics, influence by marketers such as sellers of day-old chicks, and branding. Use of antibiotics was also driven by economic factors among the farmers, sellers of day-old chicks and agro-veterinary dispensers.

CONCLUSIONS

Our findings indicate widespread use of antibiotics among poultry farmers in our study site. The use of antibiotics is influenced by an interplay of issues at the farmers' level as well as broader social, economic and structural level factors. A multifaceted One Health approach focusing on regulatory frameworks, knowledge transfer, and research is required to promote stewardship and judicious use of antibiotics.

Pharma-cartography: Navigating the complexities of antibiotic supply to rural livestock in West Bengal, India, through value chain and power dynamic analysis

Antibiotic resistance threatens provision of healthcare and livestock production worldwide with predicted negative socioeconomic impact. Antibiotic stewardship can be considered of importance to people living in rural communities, many of which depend on agriculture as a source of food and income and rely on antibiotics to control infectious diseases in livestock. Consequently, there is a need for clarity of the structure of antibiotic value chains to understand the complexity of antibiotic production and distribution in community settings as this will facilitate the development of effective policies and interventions. We used a value chain approach to investigate how relationships, behaviours, and influences are established during antibiotic distribution. Interviews were conducted with key informants (n = 17), value chain stakeholders (n = 22), and livestock keeping households (n = 36) in Kolkata, and two rural sites in West Bengal, India. Value chain mapping and an assessment of power dynamics, using manifest content analysis, were conducted to investigate antibiotic distribution and identify entry points for antibiotic stewardship. The flow of antibiotics from manufacturer to stockists is described and mapped and two local level maps showing distribution to final consumers presented. The maps illustrate that antibiotic distribution occurred through numerous formal and informal routes, many of which circumvent antibiotic use legislation. This was partly due to limited institutional power of the public sector to govern value chain activities. A 'veterinary service lacuna' existed resulting in livestock keepers having higher reliance on private and informal providers, who often lacked legal mandates to prescribe and dispense antibiotics. The illegitimacy of many antibiotic prescribers blocked access to formal training who instead relied on mimicking the behaviour of more experienced prescribers-who also lacked access to stewardship guidelines. We argue that limited institutional power to enforce existing antibiotic legislation and guide antibiotic usage and major gaps in livestock healthcare services make attempts to curb informal prescribing unsustainable. Alternative options could include addressing public sector deficits, with respect to both healthcare services and antibiotic provision, and by providing resources such as locally relevant antibiotic guidelines to all antibiotic prescribers. In addition, legitimacy of informal prescribers could be revised, which may allow formation of associations or groups to incentivise good antibiotic practices.

Crossover-Use of Human Antibiotics in Livestock in Agricultural Communities: A Qualitative Cross-Country Comparison between Uganda, Tanzania and India

Antibiotic use in animal agriculture contributes significantly to antibiotic use globally and is a key driver of the rising threat of antibiotic resistance. It is becoming increasingly important to better understand antibiotic use in livestock in low-and-middle income countries where antibiotic use is predicted to increase considerably as a consequence of the growing demand for animal-derived products. Antibiotic crossover-use refers to the practice of using antibiotic formulations licensed for humans in animals and vice versa. This practice has the potential to cause adverse drug reactions and contribute to the development and spread of antibiotic resistance between humans and animals. We performed secondary data analysis of in-depth interview and focus-group discussion transcripts from independent studies investigating antibiotic use in agricultural communities in Uganda, Tanzania and India to understand the practice of antibiotic crossover-use by medicine-providers and livestock-keepers in these settings. Thematic analysis was conducted to explore driving factors of reported antibiotic crossover-use in the three countries. Similarities were found between countries regarding both the accounts of antibiotic crossover-use and its drivers. In all three countries, chickens and goats were treated with human antibiotics, and among the total range of human antibiotics reported, amoxicillin, tetracycline and penicillin were stated as used in animals in all three countries. The key themes identified to be driving crossover-use were: (1) medicine-providers' and livestock-keepers' perceptions of the effectiveness and safety of antibiotics, (2) livestock-keepers' sources of information, (3) differences in availability of human and veterinary services and antibiotics, (4) economic incentives and pressures. Antibiotic crossover-use occurs in low-intensity production agricultural settings in geographically distinct low-and-middle income countries, influenced by a similar set of interconnected contextual drivers. Improving accessibility and affordability of veterinary medicines to both livestock-keepers and medicine-providers is required alongside interventions to address understanding of the differences between human and animal antibiotics, and potential dangers of antibiotic crossover-use in order to reduce the practice. A One Health approach to studying antibiotic use is necessary to understand the implications of antibiotic accessibility and use in one sector upon antibiotic use in other sectors.

Knowledge, Attitudes, and Practices of Community Pharmacy Professionals on Poultry Antibiotic Dispensing, Use, and Bacterial Antimicrobial Resistance in Zambia: Implications on Antibiotic Stewardship and WHO AWaRe Classification of Antibiotics

Globally, the inappropriate dispensing and use of antibiotics in animals has contributed to the development of bacterial antimicrobial resistance (AMR). In Zambia, there is insufficient information among community pharmacy professionals on antibiotic use (ABU) and AMR in food-producing animals. This study assessed community pharmacy professionals' knowledge, attitudes, and practices regarding poultry antibiotic dispensing, use, and bacterial AMR in the Lusaka district of Zambia. A cross-sectional study was conducted among 178 community pharmacy professionals between February and April 2022 using a semi-structured questionnaire. Data were analyzed using Stata version 17. Of the total participants (n = 178), 51.1% (n = 91) were pharmacists. The most dispensed antibiotic was oxytetracycline, a Watch antibiotic, mainly without prescriptions. Good knowledge of ABU and AMR was associated with work experience for more than one year (p = 0.016), while good practices were associated with male gender (p = 0.039) and work experience of more than one year (p = 0.011). The study found moderate knowledge, positive attitudes, and moderate practices of pharmacy professionals on poultry ABU and AMR. There was high dispensing of poultry antibiotics without prescriptions, which calls for strict implementation of antimicrobial stewardship and surveillance programs in poultry production in Zambia to reduce AMR.

Epidemiology of Clostridium (Clostridioides) difficile Infection in Southeast Asia

This review describes the current understanding of Clostridium (Clostridioides) difficile infection (CDI) in southeast Asia regarding the prevalence of CDI, C. difficile detection methods, antimicrobial susceptibility profiles, and the potential significance of a One Health approach to prevention and control. Our initial focus had been the Indochina region, however, due to limited studies/surveillance of CDI in Indochina, other studies in southeast Asian countries and neighboring Chinese provinces are presented here for comparison. Clostridium (Clostridioides) difficile infection is one of the most common causes of hospital-acquired gastroenteritis worldwide. Since its discovery as a cause of pseudomembranous colitis in 1978, C. difficile-related disease has been more prevalent in high-income rather than low-income countries. This may be because of a lack of knowledge and awareness about the significance of C. difficile and CDI, resulting in underreporting of true rates. Moreover, the abuse of antimicrobials and paucity of education regarding appropriate usage remain important driving factors in the evolution of CDI worldwide. The combination of underreporting of true CDI rates, along with continued misuse of antimicrobial agents, poses an alarming threat for regions like Indochina. C. difficile ribotype (RT) 027 has caused outbreaks in North America and European countries, however, C. difficile RT 017 commonly occurs in Asia. Toxin A-negative/toxin B-positive (A-B+) strains of RT 017 have circulated widely and caused outbreaks throughout the world and, in southeast Asia, this strain is endemic.

Impact of oxytetracycline exposure on the digestive system microbiota of Daphnia magna

Antibiotics are used to treat serious illness, but may also be used extraneously or as a preventative measure in many farm animals. This usage increases the potential for unintentional exposure to a variety of organisms. When antibiotics enter aquatic environments, Daphnia magna are especially vulnerable as they filter-feed in freshwater environments. Oxytetracycline (OTC) is a commonly-used broad-spectrum antibiotic used to treat a variety of mammalian diseases. In this study, the impact of OTC on D. magna mortality and gut biota were studied using both cultivation and sequencing-based approaches. Mortality rates were extremely low with the LD50 >2,000ppm. However, OTC impacted abundance and species diversity of intestinal microorganisms in the gut of the D. magna in abundance as well as species diversity. In control organisms, Pseudomonas putida and Aeromonas hydrophila were both present while only P. putida was found in OTC-exposed organisms. Disruption of the intestinal biota in D. magna could have implications on long-term survival, energy expenditure, and reproduction.

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.

Knowledge and Practices on Antibiotic Use and Antibiotic Resistance Among Smallholder Pig Farmers in Timor-Leste

Antibiotic resistance is an emerging global health threat which is linked to the overuse and misuse of antibiotics. This study was conducted to understand the knowledge and practices of smallholder pig farmers on antibiotic use and resistance in Timor-Leste. A cross-sectional study using a structured face-to-face interview was conducted in three municipalities. The interview was piloted and implemented in the local Tetun language. This study found that knowledge of antibiotics was very poor as only 12.7% (95% CI: 6.3–23.9) of farmers reported knowing what antibiotics were, and of these only one was able to correctly explain how an antibiotic worked. None of the farmers knew about antibiotic resistance and were able to explain the concept correctly. After the definition of antibiotic was explained to the farmer, only 3.6% (95% CI: 0.8–14.9) reported that their pigs had ever received antibiotics, and the majority of farmers whose pigs had not received antibiotics reported the lack of access to veterinary services. When used, antibiotics were only used for treatment with no reported use for disease prevention or growth promotion. None of the commonly used antibiotics were critically important antimicrobials. Compliance with withdrawal periods was not routinely followed. There is a need to improve access to government veterinary services for farmers in Timor-Leste, while addressing identified knowledge gaps on antibiotics and promoting prudent use practices. The findings from this study serve as baseline information to inform future interventions.

Antimicrobial use in agriculture: critical review of the factors influencing behaviour

Antimicrobial resistance (AMR) is a global health emergency affecting humans and animals, diminishing the effectiveness of medication used to treat illness. The agri-food sector has attracted increased attention for imprudent antimicrobial use (AMU) and its contribution to AMR. Thus, ascertaining farmers' and veterinarians' behaviours surrounding AMU is essential to address imprudent AMU and generate behaviour change within the agri-food sector. Therefore, the aim of this critical review is to investigate, assess and collate the current body of evidence to identify psychosocial factors including knowledge, understanding, perceptions, attitudes and behaviours surrounding AMU. Database searches were limited to articles utilizing qualitative and quantitative methodologies, available in English with no restriction on publication year. Of the 1156 articles identified, 103 were retained for this review. Findings on the psychosocial aspects were thematically analysed. Five key themes emerged from the data: (i) knowledge and awareness of antimicrobials; (ii) attitudes towards antimicrobials; (iii) influential relationships; (iv) resources; and (v) factors influencing AMU. Results indicated that to overcome barriers experienced by key stakeholders, a carefully considered, evidence-based approach, incorporating behaviour change theory, is required when designing intricate interventions/strategies, in order to elicit successful and sustained AMU behaviour change.

"If It Works in People, Why Not Animals?": A Qualitative Investigation of Antibiotic Use in Smallholder Livestock Settings in Rural West Bengal, India

Smallholder farms are the predominant livestock system in India. Animals are often kept in close contact with household members, and access to veterinary services is limited. However, limited research exists on how antibiotics are used in smallholder livestock in India. We investigated antibiotic supply, usage, and their drivers in smallholder livestock production systems, including crossover-use of human and veterinary antibiotics in two rural sites in West Bengal. Qualitative interviews were conducted with key informants (n = 9), livestock keepers (n = 37), and formal and informal antibiotic providers from veterinary and human health sectors (n = 26). Data were analysed thematically and interpreted following a One Health approach. Livestock keepers and providers used antibiotics predominantly for treating individual animals, and for disease prevention in poultry but not for growth promotion. All providers used (highest priority) critically important antimicrobials for human health and engaged in crossover-use of human antibiotic formulations in livestock. Inadequate access to veterinary drugs and services, and a perceived efficacy and ease of dosing of human antibiotics in animals drove crossover-use. Veterinary antibiotics were not used for human health due to their perceived adverse effects. Given the extent of usage of protected antibiotics and crossover-use, interventions at the community level should adopt a One Health approach that considers all antibiotic providers and livestock keepers and prioritizes the development of evidence-based guidelines to promote responsible use of antibiotics in animals.

Knowledge and practice of cattle handlers on antibiotic residues in meat and milk in Kwara State, Northcentral Nigeria

OBJECTIVES

Antibiotics are important for improving animal health and production. However, the deposition of its residues in food of animal origin intended for human consumption at non-permissible levels has generated global health concern and the need to tackle this using the "One Health Approach". This study assessed the knowledge and practice of 286 cattle handlers in Kwara State, Nigeria.

METHODS

A web-based cross sectional online survey using a semi-structured questionnaire was conducted from November to December, 2019. Univariate, bivariate and multivariate analyses were performed at 95% confidence interval to determine predictors of good knowledge and practices towards Antibiotic Residues in Meat and Milk among cattle handlers.

RESULTS

This study revealed that majority (52.7% n = 165/286) of the cattle handlers were not aware of antibiotic residues. Knowledge and practices regarding antibiotic residues were generally poor among the study population; 36.7% and 35.5% had satisfactory knowledge and practice respectively. The age (p = 0.026), gender (p = 0.006) and business duration (p = 0.001) of participants were significantly associated with their knowledge of antimicrobial residues. The effect of education on knowledge was modified by age. The odds of having poor knowledge on antibiotic residues increased 4 times among participants who were ≤40 years old than those above 40 years (Stratum Specific OR = 3.65; CI = 1.2, 11.1; p = 0.026). Knowledge levels of participants were statistically associated with their practice levels p<0.05 (OR = 2.43; CI = 1.45. 4.06; p = 0.0006).

CONCLUSION

This implies that poor knowledge is a risk factor to having poor practice among cattle handlers. Deliberate efforts towards educating cattle farmers on best farm practices in antibiotic use would prevent antibiotic residues in meat and milk. Also, an effective surveillance system for monitoring the use of veterinary drugs in Kwara State, Nigeria is crucial.

Antimicrobial Use in Animals in Timor-Leste Based on Veterinary Antimicrobial Imports between 2016 and 2019

Monitoring veterinary antimicrobial use is part of the global strategy to tackle antimicrobial resistance. The purpose of this study was to quantify veterinary antimicrobials imported into Timor-Leste between 2016 and 2019 and describe the antimicrobial import profile of importers. Data were obtained from import applications received by the Ministry of Agriculture and Fisheries (MAF) of Timor-Leste. Import quantities were analysed by antimicrobial class, importance for human medicine, recommended route of administration and type of importer. An average of 57.4 kg (s.d. 31.0 kg) and 0.55 mg/kg (s.d. 0.27 mg/kg) animal biomass of antimicrobials was imported per year. Tetracyclines (35.5%), penicillins (23.7%), and macrolides (15.9%) were the commonly imported antimicrobial classes. Antimicrobials imported for parenteral administration were most common (60.1%). MAF was the largest importer (52.4%). Most of the critically important antimicrobials for human medicine were imported by poultry farms for oral administration and use for growth promotion could not be ruled out. In conclusion, the use of antimicrobials in animals in Timor-Leste is very low, in keeping with its predominantly subsistence agriculture system. Farmer education, development of treatment guidelines, and strengthening of the veterinary service is important for addressing the potential future misuse of antimicrobials especially in the commercial poultry industry.

Antibiotics in surface water of East and Southeast Asian countries: A focused review on contamination status, pollution sources, potential risks, and future perspectives

This review provides focused insights into the contamination status, sources, and ecological risks associated with multiple classes of antibiotics in surface water from the East and Southeast Asia based on publications over the period 2007 to 2020. Antibiotics are ubiquitous in surface water of these countries with concentrations ranging from <1 ng/L to hundreds μg/L and median values from 10 to 100 ng/L. Wider ranges and higher maximum concentrations of certain antibiotics were found in surface water of the East Asian countries like China and South Korea than in the Southeast Asian nations. Environmental behavior and fate of antibiotics in surface water is discussed. The reviewed occurrence of antibiotics in their sources suggests that effluent from wastewater treatment plants, wastewater from aquaculture and livestock production activities, and untreated urban sewage are principal sources of antibiotics in surface water. Ecological risks associated with antibiotic residues were estimated for aquatic organisms and the prevalence of antibiotic resistance genes and antibiotic-resistant bacteria were reviewed. Such findings underline the need for synergistic efforts from scientists, engineers, policy makers, government managers, entrepreneurs, and communities to manage and reduce the burden of antibiotics and antibiotic resistance in water bodies of East and Southeast Asian countries.

Exploring Farmers' Reasons for Antibiotic Use and Misuse in Pig Farms in Brazil

Stressful management that makes farmed pigs susceptible to infections is associated with high antibiotic use (AMU) and resistance (AMR). Pig farmers are key stakeholders to support the international agenda pushing AMU restrictions. We interviewed 58 pig farmers on AMU/AMR, biosecurity, veterinary assistance, disease prevention and treatment, aiming to understand practices and attitudes towards the AMU/AMR problem. Farmers described a reliance on antibiotics to prevent and treat disease while neglecting biosecurity measures. We identified inappropriate AMU practices (high use of broad-spectrum antibiotics, incorrect dosage or treatment length) and unrestricted access to antibiotics, which encouraged imprudent AMU. Nevertheless, most farmers considered this AMU legitimate to guarantee herd productivity and showed unpreparedness and resistance to changing AMU practices, perceiving limitations (economic, sanitary and inspection) more easily than alternatives to reduce AMU. Agro-industries and foreign markets were mentioned, and internal consumers dismissed as potential motivators for behavioral changes. Importantly, farmers' economic, technical and social factors may limit their autonomy to change practices. We conclude that the observed distancing of pig farmers from the AMU/AMR problem limits the efficiency of policies aiming for a prudent AMU. Our study indicates a need for education, training and behavior change nudging that should include other stakeholders beyond farmers.

Non-Clinical Factors Determining the Prescription of Antibiotics by Veterinarians: A Systematic Review

The misuse of antibiotics in humans, animals, and plants is related to the spread of resistant antibiotic strains among humans and animals. In this paper, we carry out a bibliographic search of Medline, Web of Knowledge, and Cab Abstracts with the main objective of ascertaining the available evidence on non-clinical factors and attitudes that could influence the prescription of antibiotics by veterinarians. A total of 34 studies fulfilled the inclusion criteria. Whereas, veterinary health professionals' prescribing habits did not appear to be influenced by their socio-demographic characteristics, they were influenced by different attitudes, such as fear (identified in 19 out of 34 studies), self-confidence (19/34), business factors (19/34), and by complacency (16/34). Certain owner-related factors, such as lack of awareness (16/34) and demand for antibiotics (12/34), were also important, as were concurrent factors, ranging from a lack of appropriate regulations (10/34) to the expense and delays involved in performing culture and sensitivity tests (10/34) and inadequate farm hygiene (8/34). Our results appear to indicate that the non-clinical factors are potentially modifiable. This may be useful for designing interventions targeted at improving antibiotic use in animals, as part of an overall strategy to reduce the global spread of multi-resistant strains.

Understanding antibiotic use for pig farming in Thailand: a qualitative study

BACKGROUND

Antimicrobial resistance (AMR), recognised as a serious and growing threat to global health, is promoted by multiple drivers, including antibiotic use in the livestock sector. Thus, understanding factors influencing antibiotic use in livestock production is essential to the design and implementation of effective interventions to reduce AMR. This qualitative study aimed to explore the experiences and views of the key actors associated with the use of antibiotics for pig farming in Thailand, from local farmers to officers in central government institutions.

METHODS

A total of 31 in-depth interviews were conducted with different categories of actors: pig farmers (n = 13), drug retailers (n = 5), veterinarians (n = 7), government officers (n = 3) and representatives of animal and human health associations (n = 2). Themes emerging from the interviews were identified and explored using thematic analysis. In addition, direct observations were conducted in the pig farms.

RESULTS

The findings highlight the multi-faceted nature of the views and practices that may contribute to misuse or overuse of antibiotics in the study locations, including misconceptions about the nature of antibiotics and AMR (particularly among smallholders), lack of facilities and financial means to establish an antibiotic-free farm, lack of sufficient training on AMR and antibiotic prescribing for veterinarians, the profit motive of pharmaceutical companies and their ties to farm consultants, and lack of sufficient regulatory oversight.

CONCLUSIONS

Our study indicates a clear need to improve antibiotic use for pig production in Thailand. Farmers need better access to veterinary services and reliable information about animal health needs and antibiotics. Innovative investments in biosecurity could improve farm management and decrease reliance on antibiotics, although the cost of these interventions should be low to ensure wide uptake in the livestock sector. Lastly, further development of professional training and clinical guidelines, and the establishment of a code of conduct, would help improve antibiotic dispensing practices.

Scoping review of approaches for improving antimicrobial stewardship in livestock farmers and veterinarians

BACKGROUND

There has been an increased focus on antimicrobial stewardship (AMS) within the animal health domain (World Health Organization, 2015; O'Neill, 2016). Evidence of the effectiveness of interventions designed to enhance AMS is essential to support the development of this practice. This scoping review summarises for the first time the extent, range, and nature of global research activity on approaches for improving AMS in farmers and veterinarians involved in livestock farm animal management, health & well-being.

METHODS

In November 2017 AGRICOLA, CAB Abstracts, EMBASE, MEDLINE, VetsRev and the Web of Science were searched. Studies were selected by two reviewers with 30 % of excluded and all included studies being independently reviewed by another reviewer. Inclusion criteria were primary studies or literature reviews focusing on antimicrobial use (AMU) in farming or veterinary practices for food-producing animals. Outcomes were changes in, or factors influencing farmers' or veterinarians' AMS. Exclusion criteria were studies on wild or companion animals or reports of the level of, rather influencing factors for AMS, or knowledge/awareness related to antimicrobial resistance (AMR). Study characteristics and relevant outcomes were extracted, identified facilitators and barriers grouped into categories, and a narrative synthesis was conducted. The PRISMA checklist extension for scoping reviews was used to guide the reporting of the review.

RESULTS

52 studies were included in the review; seven were intervention studies and 45 were studies of facilitators and barriers of AMU or antimicrobial prescribing (AMP). Studies were predominantly from high-income countries with only seven studies from low- or middle-income countries. Evidence for effective interventions was limited in terms of number of studies and robustness of evidence. There was some effect for an educational intervention in European cattle farmers and the Yellow Card scheme for Danish pig farmers. Significant facilitators to veterinarians' prudent AMP, in the cattle and pig livestock sector, included education, veterinarians' positive attitudes towards AMU reduction, and diagnostic. For farmers, significant facilitators to reduction of AMU were most frequently related to farming management practices.

CONCLUSION

This review describes a scarcity of robust study designs and recommendations can be confidently made for better designed studies. Furthermore, greater consideration needs to be given to the outcome measures used in such studies. Nevertheless, the review summarises the evidence on the effectiveness of interventions and significant facilitators to farmers' and veterinarians' AMS, which can provide best currently available evidence to guide improvements in different livestock sectors.

Drivers of Antibiotic Resistance Transmissionin Low- and Middle-Income Countriesfrom a "One Health" Perspective-A Review

Antibiotic resistance is an ecosystem problem threatening the interrelated human-animalenvironmenthealth under the "One Health" framework. Resistant bacteria arising in onegeographical area can spread via cross-reservoir transmission to other areas worldwide either bydirect exposure or through the food chain and the environment. Drivers of antibiotic resistance arecomplex and multi-sectoral particularly in Lower- and Middle-income countries. These includeinappropriate socio-ecological behaviors; poverty; overcrowding; lack of surveillance systems; foodsupply chain safety issues; highly contaminated waste effluents; and loose rules and regulations. Inorder to examine the drivers of antibiotic resistance from a "one health" perspective, a literaturereview was conducted on three databases including PubMed, Medline and Google Scholar. A totalof 485 studies of potential relevance were selected, out of which 182 were included in this review.Results have shown that the aforementioned market failures are the leading cause for the negativeexternality of antibiotic resistance that extends in scope from the individual to the global ecosystem.Incremental and sustainable global actions can make the change, however, the problem willcontinue to prevail if governments do not prioritize the "One health" approach and if individual'saccountability is still denied in a world struggling with profound socio-economic problems.

CTX-M-55-type ESBL-producing Salmonella enterica are emerging among retail meats in Phnom Penh, Cambodia

Background

Salmonella enterica is a leading cause of human gastroenteritis. S. enterica strains that produce ESBLs (ESBL-Salm) remain rare in Europe and North America, but less is known about their prevalence among animal-derived foods in countries with weaker food safety practices and unregulated veterinary antibiotic use.

Objectives

To examine the prevalence and characteristics of ESBL-Salm from retail meats in Phnom Penh, Cambodia.

Methods

We tested fish, pork and chicken from two markets for ESBL- and carbapenemase-producing Salmonella from September-December 2016, using cefotaxime- and ertapenem-supplemented media, respectively. ESBL-Salm were sequenced and their genomes characterized. We performed plasmid conjugation experiments to assess the co-transferability of ESBL-encoding genes and MDR phenotypes.

Results

Twenty-six of 150 fish and meat samples (17%) were positive for ESBL-Salm, including 10/60 fish (17%), 15/60 pork (25%) and 1/30 chicken (3%). Carbapenemase-producing Salmonella strains were not detected. Pork-origin ESBL-Salm were primarily serotypes Rissen (10/15) or a monophasic variant of Typhimurium 4,5,12:i:- (3/15), whereas Saintpaul (3/10) and Newport (4/10) were more common among fish. Most ESBL enzymes were encoded by blaCTX-M-55 genes (24/26) harboured on conjugative IncA/C2 (n = 14) or IncHI2 (n = 10) plasmids. Resistance to up to six additional drug classes was co-transferred by each plasmid type. ESBL-Salm were resistant to almost every antibiotic recommended for severe salmonellosis treatment.

Conclusions

CTX-M-55-type S. enterica are highly prevalent among pork and fish from Phnom Penh markets and their spread appears to be mediated by MDR IncA/C2 and IncHI2 plasmids. Food safety must be improved and veterinary antibiotic use should be regulated to protect public health.

The Costs, Benefits and Human Behaviours for Antimicrobial Use in Small Commercial Broiler Chicken Systems in Indonesia

There are growing concerns over the threat to human health from the unregulated use of antimicrobials in livestock. Broiler production is of great economic and social importance in Indonesia. This study used a structured questionnaire approach to explore the human behaviours and economic drivers associated with antimicrobial use in small commercial broiler systems in Indonesia (n = 509). The study showed that antimicrobial use was high with farmers easily able to access antimicrobials through local animal medicine, however, it was difficult for farmers to access veterinary advice on responsible antimicrobial use. The most significant finding was that the relative cost of antimicrobials was low, and farmers observed improvements in productivity rates from routine antimicrobial administration. However, farmers seldom kept detailed records on farm productivity or economic costs; this is a hurdle to undertaking a more detailed economic analysis of antimicrobial use. There is a need for further research on the cost-effectiveness of alternative methods of preventing disease and ensuring that feasible alternatives are easily available. Farm-level economics and securing the food supply chain need to be central to any future policy interventions to reduce antimicrobial use in broiler systems in Indonesia and this observation is relevant at a regional and global level.

Drivers of Antibiotic Use in Poultry Production in Bangladesh: Dependencies and Dynamics of a Patron-Client Relationship

Background: There is increasing concern around the use of antibiotics in animal food production and the risk of transmission of antimicrobial resistance within the food chain. In many low and middle-income countries, including Bangladesh, the commercial poultry sector comprises small-scale producers who are dependent on credit from poultry dealers to buy day-old chicks and poultry feed. The same dealers also supply and promote antibiotics. The credit system is reliant upon informal relationships among multiple actors as part of social capital. This paper aims to describe dependencies and relationships between different actors within unregulated broiler poultry production systems to understand the social and contextual determinants of antibiotic use in low-resource settings. Methods: We used a cross-sectional qualitative design including in-depth interviews among purposefully selected commercial poultry farmers (n = 10), poultry dealers (n = 5), sales representatives of livestock pharmaceutical companies (n = 3) and the local government livestock officer as a key-informant (n = 1). We describe the food production cycle and practices relating to credit purchases and sales using social capital theory. Findings: Poultry dealers provide credit and information for small-scale poultry farmers to initiate and operate their business. In return for credit, farmers are obliged to buy poultry feed and medicine from their dealer and sell their market-ready poultry to that same dealer. All farms applied multiple antibiotics to poultry throughout the production cycle, including banned antibiotics such as colistin sulfate. The relationship between dealers and poultry farmers is reciprocal but mostly regulated by the dealers. Dealers were the main influencers of decision-making by farmers, particularly around antibiotic use as an integral part of the production cycle risk management. Our findings suggest that strategies to improve antibiotic stewardship and responsible use should exploit the patron-client relationship which provides the social and information network for small-scale farmers. Conclusion: Social capital theory can be applied to the patron-client relationship observed among poultry farmers and dealers in Bangladesh to identify influences on decision making and antibiotic use. Within unregulated food production systems, strategies to promote the prudent use of antibiotics should target commercial feed producers and livestock pharmaceutical manufacturers as a first step in developing a sustainable poultry value chain.

Drivers of Antibiotic Use in Poultry Production in Bangladesh: Dependencies and Dynamics of a Patron-Client Relationship

Background: There is increasing concern around the use of antibiotics in animal food production and the risk of transmission of antimicrobial resistance within the food chain. In many low and middle-income countries, including Bangladesh, the commercial poultry sector comprises small-scale producers who are dependent on credit from poultry dealers to buy day-old chicks and poultry feed. The same dealers also supply and promote antibiotics. The credit system is reliant upon informal relationships among multiple actors as part of social capital. This paper aims to describe dependencies and relationships between different actors within unregulated broiler poultry production systems to understand the social and contextual determinants of antibiotic use in low-resource settings. Methods: We used a cross-sectional qualitative design including in-depth interviews among purposefully selected commercial poultry farmers (n = 10), poultry dealers (n = 5), sales representatives of livestock pharmaceutical companies (n = 3) and the local government livestock officer as a key-informant (n = 1). We describe the food production cycle and practices relating to credit purchases and sales using social capital theory. Findings: Poultry dealers provide credit and information for small-scale poultry farmers to initiate and operate their business. In return for credit, farmers are obliged to buy poultry feed and medicine from their dealer and sell their market-ready poultry to that same dealer. All farms applied multiple antibiotics to poultry throughout the production cycle, including banned antibiotics such as colistin sulfate. The relationship between dealers and poultry farmers is reciprocal but mostly regulated by the dealers. Dealers were the main influencers of decision-making by farmers, particularly around antibiotic use as an integral part of the production cycle risk management. Our findings suggest that strategies to improve antibiotic stewardship and responsible use should exploit the patron-client relationship which provides the social and information network for small-scale farmers. Conclusion: Social capital theory can be applied to the patron-client relationship observed among poultry farmers and dealers in Bangladesh to identify influences on decision making and antibiotic use. Within unregulated food production systems, strategies to promote the prudent use of antibiotics should target commercial feed producers and livestock pharmaceutical manufacturers as a first step in developing a sustainable poultry value chain.

Knowledge, attitudes and practices relating to antibiotic use and antibiotic resistance among backyard pig farmers in rural Shandong province, China

China is among the world's largest consumers of antibiotics for livestock, and the demand for meat protein continues to rise. Pig production takes place at a range of facilities, including backyard pig farms. The aim of this study was to describe the knowledge, attitudes and practices of backyard pig farmers concerning antibiotic use and resistance, and to observe household storage of antibiotics for use in pigs. We conducted a cross-sectional questionnaire survey among 271 rural residents with backyard pig farms in 12 villages in one town in Shandong province. The median number of pigs per backyard farm was 14, and 82 % (222/271) of participants reported not having had any training about raising pigs. Eighteen percent of participants (48/271) reported always or often adding antibiotics to feed to keep pigs healthy and prevent diseases, and a third (88/271) of participants believed that pigs should be given antibiotics when they stop eating. Thirty percent (82/271) reported having bought antibiotics in the previous year without having first spoken with a veterinarian. Antibiotics accounted for over half of all medicines stored (55 %, 197/358), and were observed in 31 % of all households (83/271). Less than half of participants (45 %, 37/83) from households in which antibiotics for pig use were found knew that they were storing antibiotics. The most common class of antibiotics stored for use in pigs was (Q)J01C beta-lactam antibiotics, penicillins (19 %, 37/197), followed by (Q)J01F macrolides, lincosamides and streptogramins (14 %, 28/197), and (Q)J01M quinolones (12 %, 25/197). These results provide important insights into how backyard pig farmers are using antibiotics in rural China and suggest potential targets for interventions to reduce unnecessary and inappropriate use.

Antibiotic use in chicken farms in northwestern China

Background

Misuse of antibiotics in food animals contributes to an increase of antibiotic resistant bacteria transmitting to humans. China is the largest producer and user of antibiotics in the world, of which animals share more than half of the total consumption. This study aimed to explore Chinese farmer’s practice of antibiotic use and the factors associated with their use.

Methods

In this cross-sectional survey, we interviewed farmers from 88 chicken farms in northwestern China. We defined two kinds of misuse: 1) using antibiotics in the Chinese prohibited list, and 2) using antibiotics within the recommended withdrawal period. Factor analysis was used to select farmers’ knowledge variables and multinomial logistic regression was used to determine factors associated with antibiotic misuse.

Results

All the participating farmers used antibiotics on their farms. Amoxicillin was the most common antibiotic used (76.5%), followed by norfloxacin, ofloxacin, ceftriaxone and oxytetracycline. 75% of farmers used antibiotics in the prohibited list while 14.8% continued to use antibiotics during the withdrawal period. Hierarchical cluster analysis revealed three patterns of antibiotic use: 1) excessive use of non-prohibited and prohibited antibiotics or an excessive user, 2) low use of a few types of non-prohibited and moderate use of prohibited antibiotics or a low user, 3) multiple use of a variety (≥ 7 types) of non-prohibited and prohibited antibiotics or a moderate user. Farmers from medium size, family-based farms, those with a low education level and low income were more likely to misuse antibiotics. Prior formal agricultural training was associated with reducing multiple types of antibiotic use. There was a huge gap between policy and reinforcement causing antibiotic misuse in the study community.

Conclusion

Antibiotics are commonly used on chicken farms; misuse of antibiotics is high; improvement in farm sanitation, education on antibiotic use for farmers and veterinarians/pharmacists and enforcement of the regulations may reduce antibiotic use on chicken farms in China.

Transferable Mechanisms of Quinolone Resistance from 1998 Onward

While the description of resistance to quinolones is almost as old as these antimicrobial agents themselves, transferable mechanisms of quinolone resistance (TMQR) remained absent from the scenario for more than 36 years, appearing first as sporadic events and afterward as epidemics. In 1998, the first TMQR was soundly described, that is, QnrA. The presence of QnrA was almost anecdotal for years, but in the middle of the first decade of the 21st century, there was an explosion of TMQR descriptions, which definitively changed the epidemiology of quinolone resistance. Currently, 3 different clinically relevant mechanisms of quinolone resistance are encoded within mobile elements: (i) target protection, which is mediated by 7 different families of Qnr (QnrA, QnrB, QnrC, QnrD, QnrE, QnrS, and QnrVC), which overall account for more than 100 recognized alleles; (ii) antibiotic efflux, which is mediated by 2 main transferable efflux pumps (QepA and OqxAB), which together account for more than 30 alleles, and a series of other efflux pumps (e.g., QacBIII), which at present have been sporadically described; and (iii) antibiotic modification, which is mediated by the enzymes AAC(6')Ib-cr, from which different alleles have been claimed, as well as CrpP, a newly described phosphorylase.

Carriage of carbapenemase- and extended-spectrum cephalosporinase-producing Escherichia coli and Klebsiella pneumoniae in humans and livestock in rural Cambodia; gender and age differences and detection of blaOXA-48 in humans

Objectives

This study investigates the frequency and characteristics of carbapenemase‐producing Escherichia coli/Klebsiella pneumoniae (CPE/K) and extended‐spectrum cephalosporinase‐producing E. coli/K. pneumoniae (ESCE/K) in healthy humans and livestock in rural Cambodia. Additionally, household practices as risk factors for faecal carriage of ESCE/K are identified.

Methods

Faecal samples were obtained from 307 humans and 285 livestock including large ruminants, pigs and poultry living in 100 households in rural Cambodia in 2011. Each household was interviewed, and multilevel logistic model determined associations between household practices/meat consumption and faecal carriage of ESCE/K. CPE and ESCE/K were detected and further screened for colistin resistance genes.

Results

CPE/K isolates harbouring bla_OXA‐48 were identified in two humans. The community carriage of ESCE/K was 20% in humans and 23% in livestock. The same ESBL genes: bla_CTX‐M‐15, bla_CTX‐M‐14, bla_CTX‐M‐27, bla_CTX‐M‐55, bla_SHV‐2, bla_SHV‐12, bla_SHV‐28; AmpC genes: bla_CMY‐2, bla_CMY‐42,bla_DHA‐1; and colistin resistance genes: mcr‐1‐like and mcr‐3‐like were detected in humans and livestock. ESCE/K was frequently detected in women, young children, pigs and poultry, which are groups in close contact. The practice of burning or burying meat waste and not collecting animal manure indoors and outdoors daily were identified as risk factors for faecal carriage of ESCE/K.

Conclusions

Faecal carriage of E. coli and K. pneumoniae harbouring extended‐spectrum cephalosporinase genes are common in the Cambodian community, especially in women and young children. Exposure to animal manure and slaughter products are risk factors for intestinal colonization of ESCE/K in humans.

Human, animal and environmental contributors to antibiotic resistance in low-resource settings: integrating behavioural, epidemiological and One Health approaches

Antibiotic resistance (ABR) is recognized as a One Health challenge because of the rapid emergence and dissemination of resistant bacteria and genes among humans, animals and the environment on a global scale. However, there is a paucity of research assessing ABR contemporaneously in humans, animals and the environment in low-resource settings. This critical review seeks to identify the extent of One Health research on ABR in low- and middle-income countries (LMICs). Existing research has highlighted hotspots for environmental contamination; food-animal production systems that are likely to harbour reservoirs or promote transmission of ABR as well as high and increasing human rates of colonization with ABR commensal bacteria such as Escherichia coli However, very few studies have integrated all three components of the One Health spectrum to understand the dynamics of transmission and the prevalence of community-acquired resistance in humans and animals. Microbiological, epidemiological and social science research is needed at community and population levels across the One Health spectrum in order to fill the large gaps in knowledge of ABR in low-resource settings.

Patterns of antibiotic use in global pig production: A systematic review

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Many classes of antibiotic used for humans are also used in food animals, including the highest priority of the critically important antimicrobials for human medicine in the World Health Organisation's list.

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Penicillins and Tetracyclines classes were the most commonly used antibiotics in many countries.

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Improve understanding of the use of antibiotics and factors influencing antibiotic use will help promoting prudent use of antimicrobials in livestock.

This review assesses the evidence for patterns of antibiotic use in pig on the basis of papers published in peer-reviewed journals in English between 2000 and 2017. Thirty-six articles were identified and reviewed, of which more than 85% of studies were conducted in Europe and North America. Penicillins and Tetracyclines groups were the most commonly used antibiotics in many countries. Oral medication in suckling and post-weaning periods were the most common applications of antibiotic administration in pig production. Antibiotic use is driven by age-specific diseases and the common pathogens causing these conditions where epidemiological profiles varied greatly across countries. In addition, the type and size of farm were associated with antibiotic use with finisher and larger farms using more antibiotics than farrow-to-finish and smaller farms. There is variation in the use of the highest priority critically important antimicrobials in humans across studies. However, this review indicates that they are still commonly used in pig production, for treatment and prevention of infection. This evidence calls for global efforts on the prudent use of antibiotics in response to the emergence of antimicrobial resistance (AMR) in the agricultural sector.

Antimicrobials in small-scale urban pig farming in a lower middle-income country - arbitrary use and high resistance levels

Background

Administration of antimicrobials to food-producing animals is regarded as a major contributor to the overall emergence of resistance in bacteria worldwide. However, few data are available on global antimicrobial use and resistance (AMR) in livestock, especially from low- and middle-income countries.

Methods

We conducted a structured survey of 91 small-scale pig farms in the urban and peri-urban areas of Phnom Penh, Cambodia, to assess the farmers' knowledge, attitudes and practices related to antimicrobial use in their pig production. Commensal Escherichia coli was isolated from three healthy pigs from each farm (n = 261) and susceptibility testing was performed against 14 antimicrobials, using broth microdilution. Univariable logistic regression and generalized linear mixed models were used to investigate potential associations between farm characteristics, management factors and resistance to different types of antimicrobials.

Results

We found a widespread and arbitrary use of antimicrobials, often based on the farmer's own judgment. Around 66% of the farmers reported frequently self-adjusting treatment duration and dosage, and 45% had not heard about the term 'antimicrobial resistance'. The antimicrobials most commonly mentioned or kept by the farmers were amoxicillin, tylosin, gentamicin and colistin. Around 37% used a feed concentrate that contained antimicrobials, while antimicrobials for humans were used as a last-line treatment by 10% of the farmers. Commensal E. coli exhibited high prevalence of resistance to several antimicrobials considered to be of critical importance for human medicine, including ampicillin, ciprofloxacin and colistin, and multidrug-resistance was found in 79% of the samples. Higher prevalence of resistance was observed on farms that administered prophylactic antimicrobials and on farms that treated the entire group or herd in the event of disease.

Conclusion

The widespread and arbitrary use of antimicrobials in pig farming in Cambodia is highly worrisome. Overall, farmers had a low awareness of the risks and consequences related to antimicrobial use and AMR. The results presented in this study confirm the hypothesis that non-rational use of antimicrobials results in higher prevalence of AMR and highlight the need for professional animal health systems that involve medically rational use of antimicrobials in emerging economies such as Cambodia.