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

Gender and equity considerations in AMR research: a systematic scoping review

Research on gender and antimicrobial resistance (AMR) beyond women's biological susceptibility is limited. A gender and equity lens in AMR research is necessary to promote gender equality and support the effectiveness, uptake, and sustainability of real-world AMR solutions. We argue that it is an ethical and social justice imperative to include gender and related intersectional issues in AMR research and implementation. An intersectional exploration of the interplay between people's diverse identities and experiences, including their gender, socio-economic status, race, disability, age, and sexuality, may help us understand how these factors reinforce AMR risk and vulnerability and ensure that interventions to reduce the risk of AMR do not impact unevenly. This paper reports on the findings of a systematic scoping review on the interlinkages between AMR, gender and other socio-behavioural characteristics to identify priority knowledge gaps in human and animal health in LMICs. The review focused on peer-reviewed and grey literature published between 2017 and 2022. Three overarching themes were gendered division of caregiving roles and responsibilities, gender power relations in decision-making, and interactions between gender norms and health-seeking behaviours. Research that fails to account for gender and its intersections with other lines of disadvantage, such as race, class and ability, risks being irrelevant and will have little impact on the continued and dangerous spread of AMR. We provide recommendations for integrating an intersectional gender lens in AMR research, policy and practice.

Plugging the leaks: antibiotic resistance at human-animal interfaces in low-resource settings

Antibiotic resistance is one of the greatest public health challenges of our time. International efforts to curb resistance have largely focused on drug development and limiting unnecessary antibiotic use. However, in areas where water, sanitation, and hygiene infrastructure is lacking, we propose that bacterial flow between humans and animals can exacerbate the emergence and spread of resistant pathogens. Here, we describe the consequences of poor environmental controls by comparing mobile resistance elements among Escherichia coli recovered from humans and meat in Cambodia, a middle-income country with substantial human-animal connectivity and unregulated antibiotic use. We identified identical mobile resistance elements and a conserved transposon region that were widely dispersed in both humans and animals, a phenomenon rarely observed in high-income settings. Our findings indicate that plugging leaks at human-animal interfaces should be a critical part of addressing antibiotic resistance in low- and especially middle-income countries.

The Emergence of Colistin- and Imipenem-Associated Multidrug Resistance in Escherichia coli Isolates from Retail Meat

To determine the prevalence of Escherichia coli and their drug resistance profiles in fresh pork sold at two retail outlets (open-air market and closed retail stores) in Alice, South Africa. Retail meat samples (n = 176) collected from four shops (two from open-air markets and two from closed stores) were analyzed by conventional biochemical and PCR-based molecular confirmatory tests. The confirmed isolates were profiled for antimicrobial susceptibility to a panel of 12 commercial antibiotics: tetracycline, ampicillin, sulphamethoxazole trimethoprim, erythromycin, gentamycin, colistin sulphate, cefotaxime, chloramphenicol, norfloxacin, ciprofloxacin, cefuroxime, and imipenem. Colistin, ampicillin, and erythromycin resistance genes were profiled with the gene-specific primers. Multidrug resistance (MDR) and the association of imipenem and colistin in the MDR profile were determined. A total of 68 (39.08%) E. coli isolates were confirmed by PCR analysis. Resistance was most common to erythromycin (100%), followed by cefotaxime (95.58%), ampicillin (88.23%), cefuroxime (88.23%), trimethoprim-sulphamethoxazole (88.23%), and tetracycline (60.29%). Overall, 27/68 (39.70%) were MDR (≥ 3antibiotics classes). MDR E. coli isolates associated with imipenem resistance (50.00%) and colistin resistance (33.82%) were detected. The resistance genes were detected among the isolates though not in all the phenotypically resistant isolates. The detection of colistin resistance among MDR E. coli isolates from retail meat is troubling as the drug is a last resort antibiotic. Overall, the epidemiological implications of the findings are of public health importance.

Genome-associations of extended-spectrum ß-lactamase producing (ESBL) or AmpC producing E. coli in small and medium pig farms from Khon Kaen province, Thailand

Thailand is undergoing rapid intensification of livestock production where small subsistence farms and medium sized commercial farms coexist. In medium farms, antimicrobials are prescribed by a veterinarian, whereas in small farms antimicrobial use remains largely unsupervised. The impact of these differences as well as other farming practices on the emergence and composition of antimicrobial resistance genes (ARGs) remains largely unknown. We analyzed 363 genomes of extended-spectrum ß-lactamase producing (ESBL) and/or AmpC producing Escherichia coli recovered from humans and pigs at small and medium farms from the Khon Kaen province, Thailand. We tested for genome-wide associations to identify links between ARGs, host, and farm size. Pig isolates from small farms were associated with mcr and qnr genes conferring resistance to colistin and fluoroquinolones, respectively. In contrast, pig isolates from medium farms were associated with ARGs conferring resistance to drugs commonly used on medium farms (i.e., streptomycin). ESBL plasmids from small farms co-carried ARGs conferring resistance to critically important antimicrobials more frequently compared to plasmid from medium farms. Frequent ARG combinations included bla_CTX-M-55 + qnrS1 (29.8% vs 17.5% in small and medium farms, respectively), bla_CTX-M-55 + qnrS1 + mcr-3.19 (5% vs 0%), bla_CTX-M-14 + qnrS1 (9.3% vs 6.2%), and bla_CTX-M-14 + qnrS1 + mcr-1.1 (3.1% vs 0%). The co-location on plasmids of ARGs conferring resistance to critically important antimicrobials as defined by the World Health Organization is concerning, and actions to curb their spread are urgently needed. Legislation on limiting antimicrobial sales and initiatives to better inform farmers and veterinarians on appropriate antimicrobial usage and farm biosecurity could help reduce antimicrobial use on farms.

Waiting for markets to change me—High-stakeholders' views of antibiotic use and antibiotic resistance in pig production in Brazil

Overuse of veterinary antibiotics is a risk factor for antimicrobial resistance (AMR), which is a global public health emergency. More than 70% of the antibiotics consumed worldwide are used in farm animals, mainly in poultry and pig herds. Brazil is the fourth largest pork producer globally and the second-largest user of antibiotics in animals. Qualitative research can help understand the complexities around antibiotic use (AMU) in Brazilian pig herds and identify stakeholders' attitudes concerning the rational AMU and AMR in the production chain. This study aimed to explore the knowledge and attitudes of high-level professionals in the animal production chain about AMU and AMR in pig farming, the relationship with pig welfare and AMU in Brazil. We conducted 32 in-depth interviews with individuals active in the pig industry. The majority of the participants considered AMU excessive and inappropriate in pig farms in Brazil. However, attitudes toward a restrictive AMU scenario in Brazilian pig farms were predominantly negative, justified by economic, sanitary and social barriers. These included unsatisfactory management and biosecurity conditions in pig farms that, in their opinion, justify AMU to prevent diseases; issues surrounding prescription and acquisition of veterinary drugs; and employment and income relationships arising from the sale of antibiotics. The views of high-level professionals in the Brazilian livestock chain reveal antibiotics as a structural element that enables pig production. Antibiotics were viewed as essential resources for producing cheap food. Foreign markets were considered the most relevant driver of change in AMU practices rather than pressure from Brazilian consumers. A common belief expressed was that AMR is more associated with the inappropriate AMU in human medicine than in the livestock sector. Resistance to change in these stakeholders may hinder the implementation of future public policies to restrict the use of antibiotics in Brazil. Our findings suggest that successful measures to deal with the AMU/AMR challenges in the pig chain shall not be rooted in personal behavior change. Instead, honest interdisciplinary dialogues and structural changes are needed to define common grounds and a way forward to break the cycle perpetuating antibiotics as structural commodities.

Antimicrobial, Multi-Drug and Colistin Resistance in Enterobacteriaceae in Healthy Pigs in the Greater Accra Region of Ghana, 2022: A Cross-Sectional Study

There is little published information on antimicrobial resistance (AMR) in animals in Ghana. We determined the prevalence and factors associated with AMR, multi-drug resistance (MDR-resistance to ≥3 antimicrobial classes) and colistin resistance in Enterobacteriaceae in healthy pigs in Accra, Ghana. Rectal swabs obtained from the pigs on 20 farms from January to March 2022, were examined for Escherichia coli, Enterobacter spp. and Klebsiella pneumoniae. AMR was determined using standard microbiological techniques and the mcr-1 gene detected through molecular analysis. Enterobacteriaceae were isolated from 197 of 200 pigs: these comprised 195 E. coli isolates, 38 Enterobacter spp. and 3 K. pneumoniae, either singly or combined. Over 60% of E. coli were resistant to tetracycline, with 27% and 34% being resistant to amoxicillin/clavulanic acid and ampicillin, respectively; 23% of E. coli and 5% of Enterobacter spp. exhibited MDR phenotypes. Phenotypic colistin resistance was found in 8% of E. coli and Enterobacter spp., with the mcr-1 gene detected in half. Our study findings should be incorporated into on-going AMR, MDR and colistin resistance surveillance programs in Ghana. We further advocate for tailored-specific education for pig farmers on animal antimicrobial use and for strengthened regulatory policy on antimicrobial usage and monitoring in the animal production industry.

Understanding Vaccine Hesitancy in Vietnamese Fish Farmers

(1) Background: Antibiotic (AB) usage in food animals is a significant contributor to antimicrobial resistance (AMR). Vaccination can reduce the over-use of AB treatment. Little is known about farmers’ attitudes and beliefs about AB and vaccine usage in developing countries, especially in aquaculture. (2) Methods: We used the necessity/concerns framework to guide our research, where vaccine hesitancy is viewed as a function of the perceived necessity versus the perceived concerns about treatment. We measured disease and treatment perceptions in 400 Vietnamese farmers of Pangasius catfish, specifically regarding (a) chemical treatment of water, (b) antibiotic usage, and (c) vaccination of fish. (3) Results: Although farmers’ concerns about AB usage outweighed necessity beliefs, 86.5% reported having used ABs on their farm. Knowledge and attitudes towards vaccination were positive, with views of its necessity outweighing concerns. However, if available, only 67.6% said they would definitely use vaccines in the future. Farmers were more likely to use vaccines if they reported having fewer problems with fish disease, felt that any concerns about vaccines were outweighed by their perceived benefits, had less mistrust of vaccination, and had fewer concerns about commercial profiteering. (4) Conclusion: Interventions that highlight concerns about continued antibiotic use, reduce concerns, and mistrust and increase the perceived necessity of vaccines combined with greater availability of vaccines may be the most effective way of overcoming vaccine hesitancy and increase appropriate use of vaccines by Vietnamese fish farmers.

Worldwide Prevalence of mcr-mediated Colistin-Resistance Escherichia coli in Isolates of Clinical Samples, Healthy Humans, and Livestock-A Systematic Review and Meta-Analysis

Background: Antimicrobial resistance is a serious public-health problem throughout the world. Escherichia coli, the most common Gram-negative microorganism, has developed different resistance mechanisms, making treating infections difficult. Colistin is considered a last-resort drug in the treatment of infections caused by E. coli. Plasmid-mediated mobile-colistin-resistant (mcr) genes in E. coli, now disseminated globally, are considered a major public-health threat. Humans, chickens, and pigs are the main reservoirs for E. coli and the sources of antibiotic resistance. Hence, an up-to-date and precise estimate of the global prevalence of mcr resistance genes in these reservoirs is necessary to understand more precisely the worldwide spread and to more effectively implement control and prevention strategies. Methodology: Publications were identified in the PubMed database on the basis of the PRISMA guidelines. English full-text articles were selected from December 2014 to March 2021. Descriptive statistics and a meta-analysis were performed in Excel and R software, respectively. Colistin resistance was defined as the molecular-genetic detection of the mcr genes. The crude and estimated prevalence were calculated for each host and continent. The studies were divided into two groups; community-based when they involved isolates from healthy humans, chickens, or pigs, and clinical studies when they involved only hospital, outpatient, or laboratory isolates. Results: A total of 1278 studies were identified and 218 were included in this systematic review and meta-analysis, divided into community studies (159 studies) and clinical studies (59 studies). The general prevalence of mcr-mediated colistin-resistant E. coli (mcrMCRE) was 6.51% (n = 11,583/177,720), reported in 54 countries and on five continents; Asia with 119 studies followed by Europe with 61 studies registered the most articles. Asia reported the major diversity of mcr-variants (eight of nine, except mcr-2). Worldwide, chickens and pigs proved to be the principal reservoir of mcr with an estimated prevalence of 15.8% and 14.9%, respectively. Healthy humans and clinical isolates showed a lower prevalence with 7.4% and 4.2% respectively. Conclusions: In this systematic review and meta-analysis, the worldwide prevalence of mcr in E. coli isolated from healthy humans, chickens, and pigs was investigated. A wide prevalence and distribution of mcr genes was demonstrated on all continents in E. coli isolates from the selected reservoirs. Understanding the epidemiology and occurrence in the reservoirs of mcr in E. coli on different continents of the world facilitates tracing how mcr genes are transmitted and determining the infection risks for humans. This knowledge can be used to reduce the incidence of zoonotic transmission by implementing the appropriate control programs.

Global Distribution of Extended Spectrum Cephalosporin and Carbapenem Resistance and Associated Resistance Markers in Escherichia coli of Swine Origin - A Systematic Review and Meta-Analysis

Third generation cephalosporins and carbapenems are considered critically important antimicrobials in human medicine. Food animals such as swine can act as reservoirs of antimicrobial resistance (AMR) genes/bacteria resistant to these antimicrobial classes, and potential dissemination of AMR genes or resistant bacteria from pigs to humans is an ongoing public health threat. The objectives of this systematic review and meta-analysis were to: (1) estimate global proportion and animal-level prevalence of swine E. coli phenotypically resistant to third generation cephalosporins (3GCs) and carbapenems at a country level; and (2) measure abundances and global distribution of the genetic mechanisms that confer resistance to these antimicrobial classes in these E. coli isolates. Articles from four databases (CAB Abstracts, PubMed/MEDLINE, PubAg, and Web of Science) were screened to extract relevant data. Overall, proportion of E. coli resistant to 3GCs was lower in Australia, Europe, and North America compared to Asian countries. Globally, <5% of all E. coli were carbapenem-resistant. Fecal carriage rates (animal-level prevalence) were consistently manifold higher as compared to pooled proportion of resistance in E. coli isolates. bla_CTX–M were the most common 3GC resistance genes globally, with the exception of North America where bla_CMY were the predominant 3GC resistance genes. There was not a single dominant bla_CTX–M gene subtype globally and several bla_CTX–M subtypes were dominant depending on the continent. A wide variety of carbapenem-resistance genes (bla_{NDM–, VIM–, IMP–, OXA–48}, _andKPC–) were identified to be circulating in pig populations globally, albeit at very-low frequencies. However, great statistical heterogeneity and a critical lack of metadata hinders the true estimation of prevalence of phenotypic and genotypic resistance to these antimicrobials. Comparatively frequent occurrence of 3GC resistance and emergence of carbapenem resistance in certain countries underline the urgent need for improved AMR surveillance in swine production systems in these countries.

Categorisation of Antimicrobial Use in Fijian Livestock Production Systems

Antimicrobial resistance (AMR) is a major global threat to human and animal health. The use of antimicrobials in the livestock sector is considered to contribute to AMR. Therefore, a reduction in and prudent use of antimicrobials in livestock production systems have been advocated. This cross-sectional survey aimed to investigate the extent of imprudent antimicrobial use (AMU) and to determine whether the AMU practice was affected by either the farming system or species of farmed livestock in the largest island (Viti Levu) of Fiji. A total of 276 livestock enterprises were surveyed and antimicrobials were used on 309 occasions over 90 days. Overall, in 298 of 309 (96%) incidents, antimicrobials were used imprudently, comprising antibiotics, 160 of 170 (94%) and anthelmintics, 138 of 139 (99%). Prudent use of antibiotics was associated with commercial farming systems (X2 = 13, p = 0.001), but no association was observed with anthelmintic use (p > 0.05). Imprudent antibiotic use was associated with dairy (OR = 7.6, CI = 1.41, 41.57, p = 0.018) followed by layer and beef (p > 0.05) compared to broiler enterprises. Imprudent AMU was more common in the backyard and semi-commercial enterprises compared to commercial broiler enterprises. Policies promoting the prudent use of antimicrobials in Fiji should focus on smaller livestock production systems and enterprises.

Antimicrobial Resistance Surveillance of Pigs and Chickens in the Lao People’s Democratic Republic, 2018–2021

The use of antimicrobials in the livestock sector has been identified as a driver for the emergence of antimicrobial resistance (AMR), and AMR has become a growing public health and economic threat in the Lao PDR. We conducted surveillance for AMR in five provinces of the Lao PDR, in order to determine the antimicrobial susceptibility of Escherichia coli and Salmonella spp. isolated from caecal samples from slaughtered pigs at slaughterhouses and from slaughtered chickens at markets during two different time periods: 2018/2019 and 2020/2021. Antimicrobial susceptibility was determined using a panel of 14 antimicrobials using the broth microdilution technique. E. coli and Salmonella from chickens (62% and 33%, respectively) and pigs (88% and 81%, respectively) exhibited resistance to ≥3 classes of antimicrobials. Of important public health concern was the detection of Salmonella resistant to cefotaxime/ceftazidime, ciprofloxacin, and colistin, deemed as critically important antimicrobials in human medicine. This study aimed to evaluate a national sampling strategy at slaughterhouses and wet markets, and to pilot the laboratory methodologies for bacterial recovery and AMR testing. Experiences from this study will inform capacity development for a national AMR surveillance program, and these early data could serve as reference points for monitoring the impact of the Lao PDR’s national action plan to contain AMR.

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.

Exploring gender differences in knowledge and practices related to antibiotic use in Southeast Asia: A scoping review

Inappropriate use of antibiotics has been one of the main contributors to antimicrobial resistance, particularly in Southeast Asia. Different genders are prone to different antibiotic use practices. The objective of this scoping review is to understand the extent and type of evidence available on gender differences in antibiotic use across Southeast Asia. The search strategy for this scoping review involved PubMed, Semantic Scholar, BioMed Central and ProQuest. Two-level screening was applied to identify the final sample of relevant sources. Thematic content analysis was then conducted on the selected final sources to identify recurring themes related to gender differences in antibiotic use and a narrative account was developed based on the themes. Recommendations for next steps regarding reducing inappropriate antibiotic use and gender considerations that need to be made when developing future interventions were also identified. Research on gender and antibiotic use remains scarce. Studies that discuss gender within the context of antibiotic use often mention differences between males and females in knowledge, attitudes and/or behaviour, however, do not explore reasons for these differences. Gender differences in antibiotic use were generally examined in terms of: (i) knowledge of antibiotic use and antimicrobial resistance and (ii) practices related to antibiotic use. Evidence indicated that differences between males and females in knowledge and practices of antibiotic use varied greatly based on setting. This indicates that gender differences in antibiotic use are greatly contextual and intersect with other sociodemographic factors, particularly education and socioeconomic status. Educational interventions that are targeted to meet the specific needs of males and females and delivered through pharmacists and healthcare professionals were the most common recommendations for reducing inappropriate use of antibiotics in the community. Such targeted interventions require further qualitative research on factors influencing differences in knowledge and practices related to antibiotic use among males and females. In addition, there is also a need to strengthen monitoring and regulation practices to ensure accessibility to affordable, quality antibiotics through trusted sources.

Risk Factors for Antimicrobial Use on Irish Pig Farms

Simple Summary

Antimicrobial resistance (AMR) is a major threat to public health. There are concerns that antimicrobial use (AMU) in agriculture has a role in the development of AMR. Pigs are one of the main consumers of veterinary antimicrobials and a better understanding of the drivers for AMU in this sector will help in efforts to reduce use. The aim of this study was to investigate the associations between antimicrobial use, farm characteristics, biosecurity, the presence of respiratory disease on the farm and health management practices on Irish pig farms. Farms that manufactured their feed on-site had lower total AMU than farms that purchased their feed from a feed mill. Higher levels of lung abscesses and pericarditis (inflammation of the lining around the heart), both indicators of respiratory disease, were associated with increased AMU. Higher levels of pericarditis were also associated with increased use of critically important antimicrobials. Farms vaccinating against swine influenza also had higher AMU. Farms that administered prophylactic antimicrobial treatments to piglets had higher use of individual treatments and critically important antimicrobials. The results from this study show that prophylaxis and respiratory disease are the main drivers of AMU on Irish pig farms. These findings highlight areas of farm management where interventions may aid in reducing AMU on Irish pig farms.

Abstract

The threat to public health posed by antimicrobial resistance in livestock production means that the pig sector is a particular focus for efforts to reduce antimicrobial use (AMU). This study sought to investigate the risk factors for AMU in Irish pig production. Antimicrobial use data were collected from 52 farrow-to-finish farms. The risk factors investigated were farm characteristics and performance, biosecurity practices, prevalence of pluck lesions at slaughter and serological status for four common respiratory pathogens and vaccination and prophylactic AMU practices. Linear regression models were used for quantitative AMU analysis and risk factors for specific AMU practices were investigated using logistic regression. Farms that milled their own feed had lower total AMU (p < 0.001), whereas higher finisher mortality (p = 0.043) and vaccinating for swine influenza (p < 0.001) increased AMU. Farms with higher prevalence of pericarditis (p = 0.037) and lung abscesses (p = 0.046) used more group treatments. Farms with higher prevalence of liver milk spot lesions (p = 0.018) and farms practising prophylactic AMU in piglets (p = 0.03) had higher numbers of individual treatments. Farms practising prophylactic AMU in piglets (p = 0.002) or sows (p = 0.062) had higher use of cephalosporins and fluoroquinolones. This study identified prophylactic use and respiratory disease as the main drivers for AMU in Irish pig production. These findings highlight areas of farm management where interventions may aid in reducing AMU on Irish pig farms.

Quantification of antimicrobial use in Fijian livestock farms

Antimicrobial resistance (AMR) is a major threat to humans and animals globally. Antimicrobial stewardship has been acknowledged as a primary strategy to tackle AMR. An important first step for antimicrobial stewardship is to quantify antimicrobial use (AMU). In Fiji, there are currently no data on AMU in livestock farms. This study aimed to quantify AMU in different livestock enterprises (beef, dairy, broiler, and layer) and farming systems (backyard, semi-commercial and commercial) in Central and Western divisions of Viti Levu, Fiji. A survey with 210 livestock farmers and 26 managers representing 276 enterprises was conducted between May and September 2019. The difference in AMU between different livestock enterprises and farming systems was investigated using ANOVA. In Fiji, the estimated annual antibiotic use in livestock was lower than the global average (44 compared with 118 mg/PCU). However, this use was concentrated in 56% of participant farms (the remaining 44% did not use antimicrobials). Total estimated quarterly anthelmintic use (20,797 mg) was not affected by farming systems but was highest (P < 0.001) in dairy enterprises (24,120 mg) and lowest in broiler enterprises (4 mg). Quarterly antibiotic use was different between the enterprises regardless of the metrics used to quantify the use (P < 0.05). Total estimated quarterly mg/PCU of antibiotic use was highest (P < 0.001) in broiler enterprises (12.4 mg/PCU) and lowest in beef enterprises (0.2 mg/PCU). For all other ESVAC metrics, total estimated antibiotic use was higher in poultry and lower in cattle enterprises. Backyard systems used less antibiotics (total mg) than commercial systems, but for other metrics, the trend was reversed. The use of both antibiotics and anthelmintics (rather than antibiotics or anthelmintics alone, or no AMU) was associated with dairy enterprises (Χ² = 123, P < 0.001). Further studies should be conducted to quantify and evaluate the drivers of AMU in Fijian livestock farms. In addition, differences in AMU between different enterprises and farming systems suggest that strategies to reduce AMU should be tailored to specific settings.

Development of a 3-transcript host expression assay to differentiate between viral and bacterial infections in pigs

Indiscriminate use of antibiotics to treat infections that are of viral origin contributes to unnecessary use which potentially may induce resistance in commensal bacteria. To counteract this a number of host gene transcriptional studies have been conducted to identify genes that are differently expressed during bacterial and viral infections in humans, and thus could be used as a tool to base decisions on the use of antibiotics. In this paper, we aimed to evaluate the potential of a selection of genes that have been considered biomarkers in humans, to differentially diagnose bacterial from viral infections in the pig. First porcine PBMC were induced with six toll-like receptor (TLR) agonists (FliC, LPS, ODN 2216, Pam3CSK4, poly I:C, R848) to mimic host gene expression induced by bacterial or viral pathogens, or exposed to heat-killed Actinobacillus pleuropneumoniae or a split influenza virus. Genes that were differentially expressed between bacterial and viral inducers were further evaluated on clinical material comprising eleven healthy pigs, and six pigs infected with A. pleuropneumoniae. This comprised three virally upregulated genes (IFI44L, MxA, RSAD2) and four bacterially upregulated genes (IL-1β, IL-8, FAM89A, S100PBP). All six infected pigs could be differentially diagnosed to healthy pigs using a host gene transcription assay based on the geometric average of the bacterially induced genes IL-8 and S100PBP over that of the virally induced gene MxA.

Antimicrobial Resistance Pilot Surveillance of Pigs and Chickens in Vietnam, 2017-2019

Antimicrobial use (AMU) and antimicrobial resistance (AMR) are a growing public health and economic threat in Vietnam. We conducted a pilot surveillance programme in five provinces of Vietnam, two in the south and three in the north, to identify antimicrobial resistance (AMR) in rectal swab samples from pigs and fecal samples from chickens at slaughter points during three different points in time from 2017 to 2019. Escherichia coli (E. coli) and non-typhoidal Salmonella (NTS) isolates were tested for antimicrobial susceptibility using disk diffusion assay for 19 antimicrobial agents belonging to nine antimicrobial classes and Etest for colistin (polymyxin). Almost all E. coli (99%; 1029/1042) and NTS (96%; 208/216) isolates were resistant to at least one antimicrobial agent; 94% (981/1042) of E. coli and 89% (193/216) of NTS isolates were multidrug-resistant (MDR). Higher proportions of E. coli and NTS isolated from chickens were resistant to all antimicrobial classes than those isolates from pigs. There was a significantly higher proportion of MDR NTS isolates from the southern provinces of Ho Chi Minh City and Long An (p = 0.008). Although there were increasing trends of NTS in proportion of resistance to fluoroquinolone over the three surveillance rounds, there was a significant decreasing trend of NTS in proportion of resistance to polymyxin (p = 0.002). It is important to establish an annual AMR surveillance program for livestock in Vietnam to assess the impact of interventions, observe trends and drive decision making that ultimately contributes to reducing AMR public health threat.

Indications for the use of highest priority critically important antimicrobials in the veterinary sector

BACKGROUND

Among the measures taken to preserve the clinical efficacy of highest priority critically important antimicrobials (HP-CIAs), the WHO has recommended avoiding their use in food-producing animals. Little is known regarding the indications for which different antimicrobial classes are used in animals, even in countries where data on antimicrobial use are available.

OBJECTIVES

To outline, in a narrative review, the diseases for which HP-CIAs are used in veterinary medicine, highlighting incongruences with international guidelines and disease conditions where effective alternatives to HP-CIAs are missing.

METHODS

Scientific literature, national reports and expert opinion were used to describe the indications for the use of HP-CIAs in the main food-producing (pigs, cattle and poultry) and companion (horses, dogs and cats) animal species.

RESULTS

The most common indications for use of HP-CIAs are enteric and respiratory infections in pigs, cattle and poultry, urogenital infections in dogs and cats and respiratory infections in horses. In some instances, no valid and convenient alternatives to colistin and macrolides are available against certain porcine enteric and bovine respiratory pathogens. Effective, legal and convenient alternatives to HP-CIAs are also lacking for managing common infections in cats, for which oral administration is difficult, Rhodococcus equi infections in horses, some enteric and respiratory infections in poultry and MDR infections in all companion animal species.

CONCLUSIONS

Future research and stewardship programmes should focus on the disease conditions identified by this review to reduce the use of HP-CIAs in the veterinary sector.

Exploring the Antibiotic Resistance Burden in Livestock, Livestock Handlers and Their Non-Livestock Handling Contacts: A One Health Perspective

Antibiotics are freqeuently used in the livestock sector in low- and middle-income countries for treatment, prophylaxis, and growth promotion. However, there is limited information into the zoonotic prevalence and dissemination patterns of antimicrobial resistance (AMR) within these environments. In this study we used pig farming in Thailand as a model to explore AMR; 156 pig farms were included, comprising of small-sized (<50 sows) and medium-sized (≥100 sows) farms, where bacterial isolates were selectively cultured from animal rectal and human fecal samples. Bacterial isolates were subjected to antimicrobial susceptibility testing (AST), and whole-genome sequencing. Our results indicate extensive zoonotic sharing of antibiotic resistance genes (ARGs) by horizontal gene transfer. Resistance to multiple antibiotics was observed with higher prevalence in medium-scale farms. Zoonotic transmission of colistin resistance in small-scale farms had a dissemination gradient from pigs to handlers to non-livestock contacts. We highly recommend reducing the antimicrobial use in animals’ feeds and medications, especially the last resort drug colistin.

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.

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.

Antimicrobial Usage Factors and Resistance Profiles of Shiga Toxin-Producing Escherichia coli in Backyard Production Systems From Central Chile

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen and important cause of foodborne disease worldwide. Many animal species in backyard production systems (BPS) harbor STEC, systems characterized by low biosecurity and technification. No information is reported on STEC circulation, antimicrobial resistance (AMR) and potential drivers of antimicrobial usage in Chilean BPS, increasing the risk of maintenance and transmission of zoonotic pathogens and AMR generation. Thus, the aim of this study was to characterize phenotypic and genotypic AMR and to study the epidemiology of STEC isolated in BPS from Metropolitana region, Chile. A total of 85 BPS were sampled. Minimal inhibitory concentration and whole genome sequencing was assessed in 10 STEC strain isolated from BPS. All strains were cephalexin-resistant (100%, n = 10), and five strains were resistant to chloramphenicol (50%). The most frequent serotype was O113:H21 (40%), followed by O76:H19 (40%), O91:H14 (10%), and O130:H11 (10%). The stx1 type was detected in all isolated strains, while stx2 was only detected in two strains. The Stx subtype most frequently detected was stx1c (80%), followed by stx1a (20%), stx2b (10%), and stx2d (10%). All strains harbored chromosomal bla_AmpC. Principal component analysis shows that BPS size, number of cattle, pet and horse, and elevation act as driver of antimicrobial usage. Logistic multivariable regression shows that recognition of diseases in animals (p = 0.038; OR = 9.382; 95% CI: 1.138–77.345), neighboring poultry and/or swine BPS (p = 0.006; OR = 10.564; 95% CI: 1.996–55.894), visit of Veterinary Officials (p = 0.010; OR = 76.178; 95% CI: 2.860–2029.315) and close contact between animal species in the BPS (p = 0.021; OR = 9.030; 95% CI: 1.385–58.888) increase significantly the risk of antimicrobial use in BPS. This is the first evidence of STEC strains circulating in BPS in Chile, exhibiting phenotypic AMR, representing a threat for animal and public health. Additionally, we identified factors acting as drivers for antimicrobial usage in BPS, highlighting the importance of integration of these populations into surveillance and education programs to tackle the potential development of antimicrobial resistance and therefore the risk for ecosystemic health.

Caretaker knowledge, attitudes, and practices (KAP) and carriage of extended-spectrum beta-lactamase-producing E. coli (ESBL-EC) in children in Quito, Ecuador

Background

The rapid spread of extended-spectrum beta-lactamase-producing E. coli (ESBL-EC) is an urgent global health threat. We examined child caretaker knowledge, attitudes, and practices (KAP) towards proper antimicrobial agent use and whether certain KAP were associated with ESBL-EC colonization of their children.

Methods

Child caretakers living in semi-rural neighborhoods in peri-urban Quito, Ecuador were visited and surveyed about their KAP towards antibiotics. Fecal samples from one child (less than 5 years of age) per household were collected at two time points between July 2018 and May 2019 and screened for ESBL-EC. A repeated measures analysis with logistic regression was used to assess the relationship between KAP levels and child colonization with ESBL-EC.

Results

We analyzed 740 stool samples from 444 children living in households representing a range of environmental conditions. Of 374 children who provided fecal samples at the first household visit, 44 children were colonized with ESBL-EC (11.8%) and 161 were colonized with multidrug-resistant E. coli (43%). The prevalences of ESBL-EC and multidrug-resistant E. coli were similar at the second visit (11.2% and 41.3%, respectively; N = 366). Only 8% of caretakers knew that antibiotics killed bacteria but not viruses, and over a third reported that they “always” give their children antibiotics when the child’s throat hurts (35%). Few associations were observed between KAP variables and ESBL-EC carriage among children. The odds of ESBL-EC carriage were 2.17 times greater (95% CI: 1.18–3.99) among children whose caregivers incorrectly stated that antibiotics do not kill bacteria compared to children whose caregivers correctly stated that antibiotics kill bacteria. Children from households where the caretaker answered the question “When your child’s throat hurts, do you give them antibiotics?” with “sometimes” had lower odds of ESBL-EC carriage than those with a caretaker response of “never” (OR 0.48, 95% CI 0.27–0.87).

Conclusion

Caregivers in our study population generally demonstrated low knowledge regarding appropriate use of antibiotics. Our findings suggest that misinformation about the types of infections (i.e. bacterial or viral) antibiotics should be used for may be associated with elevated odds of carriage of ESBL-EC. Understanding that using antibiotics is appropriate to treat infections some of the time may reduce the odds of ESBL-EC carriage. Overall, however, KAP measures of appropriate use of antibiotics were not strongly associated with ESBL-EC carriage. Other individual- and community-level environmental factors may overshadow the effect of KAP on ESBL-EC colonization. Intervention studies are needed to assess the true effect of improving KAP on laboratory-confirmed carriage of antimicrobial resistant bacteria, and should consider community-level studies for more effective management.

Assessing Upstream Determinants of Antibiotic Use in Small-Scale Food Animal Production through a Simulated Client Method

Small-scale food animal production has been celebrated as a means of economic mobility and improved food security but the use of veterinary antibiotics among these producers may be contributing to the spread of antibiotic resistance in animals and humans. In order to improve antibiotic stewardship in this sector, it is critical to identify the drivers of producers’ antibiotic use. This study assessed the determinants of antibiotic use in small-scale food animal production through simulated client visits to veterinary supply stores and surveys with households that owned food animals (n = 117) in Ecuador. Eighty percent of households with food animals owned chickens and 78% of those with chickens owned fewer than 10 birds. Among the households with small-scale food animals, 21% reported giving antibiotics to their food animals within the last six months. Simulated client visits indicated that veterinary sales agents frequently recommended inappropriate antibiotic use, as 66% of sales agents recommended growth promoting antibiotics, and 48% of sales agents recommended an antibiotic that was an inappropriate class for disease treatment. In contrast, few sales agents (3%) were willing to sell colistin, an antibiotic banned for veterinary use in Ecuador as of January 2020, which supports the effectiveness of government regulation in antibiotic stewardship. The cumulative evidence provided by this study indicates that veterinary sales agents play an active role in promoting indiscriminate and inappropriate use of antibiotics in small-scale food animal production.

Antibiotic use in pig farms at different levels of intensification-Farmers' practices in northeastern Thailand

Understanding the patterns and drivers of antibiotic use in livestock is crucial for tailoring efficient incentives for responsible use of antibiotics. Here we compared routines for antibiotic use between pig farms of two different levels of intensification in Khon Kaen province in Thailand. Among the 113 family-owned small-scale farms (up to 50 sows) interviewed did 76% get advice from the pharmacy about how to use the antibiotics and 84% used it primarily for treating disease. Among the 51 medium-scale-farms (100–500 sows) belonging to two companies did 100% get advice about antibiotic use from the company’s veterinarian (P<0.0001) and 94% used antibiotics mostly as disease preventive measure (P<0.0001). In 2 small scale farms 3^rd generation cephalosporins, tylosin or colistin were used; antibiotics belonging to the group of highest priority critically important antimicrobials for human medicine. Enrofloxacin, belonging to the same group of antimicrobials, was used in 33% of the small-scale and 41% of the medium-scale farms. In the latter farms, the companies supplied 3–4 antibiotics belonging to different classes and those were the only antibiotics used in the farms. The median and mean estimated expenditure on antibiotics per sow was 4.8 USD (IQR = 5.8) for small-scale farms and 7 USD and 3.4 USD for the medium-scale farms belonging to the two respective companies. Our observations suggest to target the following areas when pig farming transitions from small-scale to medium-scale: (i) strengthening access to professional animal health services for all farmers, (ii) review of the competence and role of veterinary pharmacies in selling antibiotics and (iii) adjustment of farming company animal health protocols towards more medically rational use of antibiotics.

Antimicrobial Resistance in Agri-Food Chain and Companion Animals as a Re-emerging Menace in Post-COVID Epoch: Low-and Middle-Income Countries Perspective and Mitigation Strategies

Antimicrobial resistance (AMR) leads to enormous financial losses from issues such as high morbidity, mortality, man-days lost, hospital length of stay, health-care, and social costs. In humans, over prescription of antimicrobials, which is presumably higher during COVID, has been identified as the major source of selection for antimicrobial resistant bacteria; however, use of antimicrobials in food and companion animals, fish, and vegetables, and the environmental resistance gene pool, also play important roles. The possibilities of unnecessary use of antibiotics as prophylaxis during and after COVID in livestock and companion animals exist in low-and middle-income countries. A considerable loss in gross domestic product (GDP) is also projected in low-and middle-income countries (LMICs) due to AMR by the year 2050, which is further going to be reduced due to economic slowdown in the post-COVID period. Veterinary hospitals dedicated to pets have cropped up, especially in urban areas of LMICs where use of antimicrobials has also been increased substantially. The inevitable preventive habit built up during COVID with the frequent use of hand sanitizer might trigger AMR due to the presence of cross-resistance with disinfectants. In LMICs, due to the rising demand for animal protein, industrial food animal production (IFAP) is slowly replacing the small-scale backyard farming system. The lack of stringent regulations and monitoring increased the non-therapeutic use of antimicrobials in industrial farms where the persistence of antimicrobial resistant bacteria has been associated with several factors other than antimicrobial use, such as co-resistance, cross-resistance, bacterial fitness, mixing of new and old animals, and vectors or reservoirs of bacterial infection. The present review describes types of antimicrobials used in agri-food chains and companion animals in LMICs with identification of the gap in data, updated categories of prevalent antimicrobial resistant bacteria, the role of animal farms as reservoirs of resistant bacteria, and mitigation strategies, with a special focus on the pivotal strategy needed in the post-COVID period.

Artemisinin Loaded mPEG-PCL Nanoparticle Based Photosensitive Gelatin Methacrylate Hydrogels for the Treatment of Gentamicin Induced Hearing Loss

Objective

Artemisinin (ART) is a natural anti-malarial sesquiterpene lactone which has the ability to treat and activate the CLRN1 pathway to play a pivotal role in hearing loss and hair cell function. To investigate the therapeutic effect of ART in hearing loss induced by gentamicin (GM), an ART-loaded poly(ethylene glycol)-b-poly(ε-caprolactone) mPEG-PCL nanoparticle-based photosensitive hydrogel was developed and tested in this study.

Materials and Methods

Artemisinin-loaded mPEG-PCL nanoparticles (mPEG-PCL-ART-NPs) were prepared by a double emulsion method and the formulation was optimized by an orthogonal experimental design. The particle size, zeta potential, morphology and in vitro dissolution of the mPEG-PCL-ART-NPs were well characterized. Biocompatibility of the mPEG-PCL-ART-NPs were tested on HeLa cells with an MTT assay. The photo-crosslinkable biodegradable gelatin methacrylate (GelMA) hydrogel was prepared and its physicochemical properties (such as substitution, photocrosslinking efficiency, cell viability morphology, mechanical and swelling properties) were evaluated. Finally, mPEG-PCL-ART-FITC-NPs, loaded mPEG-PCL-ART-NPs, and loaded mPEG-PCL-ART-NPs-GelMA hydrogels were fabricated and a GM toxicity-induced guinea pig ear damage model was established to determine the effectiveness of the materials on returning auditory function and cochlea pathomorphology.

Results

The zeta potential of the mPEG-PCL-ART-NPs was about −38.64 ± 0.21 mV and the average size was 167.51 ± 1.87 nm with an encapsulation efficacy of 81.7 ± 1.46%. In vitro release studies showed that the mPEG-PCL-ART-NPs possessed a sustained-release effect and the MTT experiments showed good biocompatibility properties of the drug-loaded nanoparticles. The results indicated that the 5% GelMA with MA-4% hydrogel had a better crosslinking density and 3D structure for drug loading and drug delivery than controls. Skin penetration results showed that the mPEG-PCL-ART-NPs increased adhesive capacity and avoided fast diffusion in the skin. Most importantly, auditory brainstem response results indicated that the mPEG-PCL-ART-NPs-GelMA hydrogel alleviated hearing loss induced by GM.

Conclusion

These results suggested that the presently fabricated mPEG-PCL-ART-NPs-GelMA hydrogels are promising formulations for the treatment of hearing loss induced by GM and lay the foundation for further clinical research of inner ear induction therapy.

Antimicrobial Resistance in Humans and Animals: Rapid Review of Psychological and Behavioral Determinants

A rapid review of current evidence examining psychological issues regarding the use of antibiotics and antimicrobials and resistance to these in both human and animal populations was conducted. Specific areas of interest were studies examining psychological determinants of AMR and interventions which attempt to change behavior with regard to AMR in the general population; animals; and fish, in particular. Although there is some evidence of the effectiveness of behavior change in general human populations, there is limited evidence in farmed animals, with a particular dearth in fish farming. We conclude there is an urgent need for more psychological research to identify major barriers and facilitators to change and evaluate the effectiveness of theory-based interventions aimed at reducing AM use in food production animals, including the promotion of alternatives to AMs, such as vaccination.

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.

A cross sectional study of prevalence and risk factors associated with subclinical mastitis and intramammary infections, in dairy herds linked to milk collection centers in Rwanda

The objective of this cross-sectional study was to investigate prevalence, causative udder pathogens and their antimicrobial resistance (AMR), as well as cow and herd risk factors associated with subclinical mastitis (SCM = cows with at least one udder quarter with california mastitis test (CMT) score > 2) and intramammary infections (IMI) caused by Staphylococcus(S.) aureus or Non aureus staphylococci (NAS) in dairy cows linked to Milk Collection Centers (MCCs) in Rwanda. Screening for SCM with the CMT was done on 572 cows from 404 herds linked to two MCCs in each of four provinces. Milk from udder quarters with a CMT score ≥3 (scale 1-5) was sampled for bacteriological analysis. Antimicrobial resistance was evaluated in 60 selected S. aureus isolates. Multivariable mixed effect and ordinary logistic regression analyses were performed to identify cow and herd level risk factors associated with SCM, NAS or S. aureus IMI in cows. The prevalence of SCM was 37.3 % at quarter level and 62.0 % at cow level. Bacteria were isolated 73.7 % of the cultured milk samples, whereas 23.3 % were culture-negative and 3.0 % were contaminated. Staphylococcus aureus and NAS were the most prevalent pathogens, representing more than half of all bacteriological findings. Staphylococcus chromogenes and S. epidermidis were the most prevalent NAS species identified. Of the S. aureus strains 83.3 % were resistant for penicillin, 100 % for clindamycin and 20 % tetracycline. The risk factor analysis showed that an increased stage of lactation, dirty udder and legs in single cow herds and lack of calf suckling the dam, dirty udder and legs and lack of feeding cow after milking in multiple cow herds were significantly (P < 0.05) associated with an increased odds of SCM. Similarly, increasing stage of lactation in single cow herds, and housing cows in individual cattle kraal or on earthen floor and hand washing between cows during milking in multiple cow herds were associated with increased odds for NAS IMI. Poor hygiene of milking area in single cow herds and absence of foremilk stripping in multiple cow herds were significantly (P < 0.05) associated with increased odds for S. aureus IMI in cows. In conclusion, SCM prevalence was high across MCCs. The majority of identified pathogens were contagious in nature and they exhibited resistance to penicillin. Control of the identified risks factors and improved biosecurity through adoption of best practices, and farmer training could contribute to lowering SCM prevalence in Rwanda.

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.

Meat and Fish as Sources of Extended-Spectrum β-Lactamase-Producing Escherichia coli, Cambodia

We compared extended-spectrum β-lactamase-producing Escherichia coli isolates from meat and fish, gut-colonized women, and infected patients in Cambodia. Nearly half of isolates from women were phylogenetically related to food-origin isolates; a subset had identical multilocus sequence types, extended-spectrum β-lactamase types, and antimicrobial resistance patterns. Eating sun-dried poultry may be an exposure route.

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.

Antimicrobial resistance in Cambodia: a review

OBJECTIVES

Following the launch of the Global Antimicrobial Resistance Surveillance System (GLASS), antimicrobial resistance (AMR) rates in many countries remain poorly described. This review provides an overview of published AMR data from Cambodia in the context of recently initiated national human and food-animal surveillance.

METHODS

PubMed and the Cochrane Database of Systematic Reviews were searched for articles published from 2000 to 2018, which reported antimicrobial susceptibility testing (AST) data for GLASS specific organisms isolated from Cambodia. Articles were screened using strict inclusion/exclusion criteria. AST data was extracted, with medians and ranges of resistance rates calculated for specific bug-drug combinations.

RESULTS

Twenty-four papers were included for final analysis, with 20 describing isolates from human populations. Escherichia coli was the most commonly described organism, with median resistance rates from human isolates of 92.8% (n=6 articles), 46.4% (n=4), 55.4% (n=8), and 46.4% (n=5) to ampicillin, 3^rd generation cephalosporins, fluoroquinolones, and gentamicin respectively.

CONCLUSIONS

Whilst resistance rates are high for several GLASS organisms, there were insufficient data to draw robust conclusions about the AMR situation in Cambodia. The recently implemented national AMR surveillance systems will begin to address this data gap.

Antibacterial activity and mode of action of acetone crude leaf extracts of under-investigated Syzygium and Eugenia (Myrtaceae) species on multidrug resistant porcine diarrhoeagenic Escherichia coli

BACKGROUND

Diarrhoea, a global economically important disease burden affecting swine and, especially piglets, is commonly caused by infection with entero-toxigenic E. coli (ETEC). Adherence of ETEC to porcine intestinal epithelial cells following infection, is necessary for its pathogenesis. While antimicrobials are commonly given as therapy or as feed additives for prophylaxis against microbial infections, the concern over increased levels of antimicrobial resistance necessitate the search for safe and effective alternatives in livestock feed. Attention is shifting to natural products including plants as suitable alternatives to antimicrobials. The activity of acetone crude leaf extracts of nine under-explored South African endemic plants from the Myrtaceae family with good antimicrobial activity were tested against pathogenic E. coli of porcine origin using a microplate serial dilution method. Bioautography, also with p-iodonitrotetrazolium violet as growth indicator was used to view the number of bioactive compounds in each extract. In vitro toxicity of extracts was determined against Caco-2 cells using the 3-(4,5-dimethythiazolyl-2)-2,5-diphenyltetrazolium bromide reduction assay. The antimicrobial susceptibility of E. coli isolates was tested on a panel of antimicrobials using the Kirby-Bauer agar diffusion method while the anti-adherence mechanism was evaluated using a Caco-2 cell enterocyte anti-adhesion model.

RESULTS

The MIC of the extracts ranged from 0.07-0.14 mg/mL with S. legatii having the best mean MIC (0.05 mg/mL). Bioautography revealed at least two active bands in each plant extract. The 50% lethal concentration (LC₅₀) values ranged between 0.03-0.66 mg/mL. Eugenia zeyheri least cytotoxic (LC₅₀ = 0.66 mg/ml) while E. natalitia had the highest cytotoxicity (LC₅₀ = 0.03 mg/mL). All the bacteria were completely resistant to doxycycline and colistin sulphate and many of the plant extracts significantly reduced adhesion of E. coli to Caco-2 cells.

CONCLUSIONS

The extracts of the plants had good antibacterial activity as well as a protective role on intestinal epithelial cells against enterotoxigenic E. coli bacterial adhesion. This supports the potential use of these species in limiting infection causes by E. coli. Some of these plants or extracts may be useful as phytogenic feed additives but it has to be investigated by animal feed trials.

Assessment of Drivers of Antimicrobial Usage in Poultry Farms in the Mekong Delta of Vietnam: A Combined Participatory Epidemiology and Q-Sorting Approach

In the Mekong Delta of Vietnam, poultry farmers use high amounts of antimicrobials, but little is known about the drivers that influence this usage. We aimed to identify these drivers using a novel approach that combined participatory epidemiology (PE) and Q-sorting (a methodology that allows the analysis of the subjectivity of individuals facing a common phenomenon). A total of 26 semi-structured collective interviews were conducted with 125 farmers representative of the most common farming systems in the area (chickens, meat ducks, and mobile grazing ducks), as well as with 73 farmers' advisors [veterinarians, veterinary drug shop owners, and government veterinarians/commune animal health workers (CAHWs)] in five districts of Dong Thap province (Mekong Delta). Through these interviews, 46 statements related to the antimicrobials' perceived reliability, costs, and impact on flock health were created. These statements were then investigated on 54 individuals (28 farmers and 26 farmers' advisors) using Q-sorting interviews. Farmers generally indicated a higher propensity for antimicrobial usage (AMU) should their flocks encounter bacterial infections (75.0-78.6%) compared with viral infections (8.3-66.7%). The most trusted sources of advice to farmers were, in decreasing order: government veterinarian/CAHWs, their own knowledge/experience, veterinary drug shop owners, and sales persons from pharmaceutical and feed companies. The highest peak of AMU took place in the early phase of the production cycle. Farmers and their advisors showed considerable heterogeneity of attitudes with regards to AMU, with, respectively, four and three discourses representing their views on AMU. Overall, farmers regarded the cost of AMU cheaper than other disease management practices implemented on their farms. However, they also believed that even though these measures were more expensive, they would also lead to more effective disease prevention. A key recommendation from this finding would be for the veterinary authorities to implement long-term sustainable training programs aiming at reducing farmers' reliance on antimicrobials.

Antimicrobial Usage in Animal Production: A Review of the Literature with a Focus on Low- and Middle-Income Countries

Antimicrobial use (AMU) in animal production is a key contributor to antimicrobial resistance (AMR) worldwide. As consumption of animal protein and associated animal production is forecast to increase markedly over coming years in low- and middle-income countries (LMICs), accurate monitoring of AMU has become imperative. We summarized data from 89 scientific studies reporting AMU data in animal production published in English since 1998, identified through the 'ISI Web of Knowledge' search engine. The aims were as follows: (a) to describe methodologies and metrics used to quantify AMU; (b) to summarize qualitative (on-farm prevalence of use) and quantitative (amounts of antimicrobial active principle) data, in order to identify food animal species at the highest risk of AMU; and (c) to highlight data gaps from LMICs. Only 17/89 (19.1%) studies were conducted in LMICs. Sixty (67.3%) reported quantitative data use, with 'daily doses per animal-time' being the most common metric. AMU was greatest in chickens (138 doses/1000 animal-days [inter quartile range (IQR) 91.1⁻438.3]), followed by swine (40.2 [IQR 8.5⁻120.4]), and dairy cattle (10.0 [IQR 5.5⁻13.6]). However, per kg of meat produced, AMU was highest in swine, followed by chickens and cattle. Our review highlights a large deficit of data from LMICs, and provides a reference for comparison with further surveillance and research initiatives aiming to reduce AMU in animal production globally.