Antimicrobial Use in Brazilian Swine Herds: Assessment of Use and Reduction Examples

Unveiling the landscape of resistance against high priority critically important antimicrobials in food-producing animals across Africa: A scoping review

The rapid population growth in Africa is associated with an increasing demand for livestock products which in turn can lead to antimicrobial use. Antimicrobial usage in animals contributes to the emergence and selection of resistant bacteria which constitutes a serious public health threat. This study aims to review and summarize the available information on highest priority critically important antimicrobials (HPCIAs) resistance in livestock production in Africa. This work will help to inform future policies for controlling antimicrobial resistance (AMR) in the food production chain. A scoping review was conducted according to the Cochrane handbook and following PRISMA 2020 guidelines for reporting. Primary research studies published after 1999 and reporting resistance of Escherichia coli, Enterococcus spp, Staphylococcus aureus, Salmonella spp, and Campylobacter spp to HPCIAs in poultry, cattle, pigs, goats, and sheep in Africa were searched in four databases. A total of 312 articles were included in the review. The majority of the studies (40.7) were conducted in North African countries. More than 49.0% of included studies involved poultry and 26.2% cattle. Cephalosporins and quinolones were the most studied antimicrobial classes. Of the bacteria investigated in the current review, E. coli (41.7%) and Salmonella spp (24.9%) represented the most commonly studied. High levels of resistance against erythromycin in E. coli were found in poultry (MR 96.1%, IQR 83.3-100.0%), cattle (MR 85.7%, IQR 69.2-100.0%), and pigs (MR 94.0%, IQR 86.2-94.0%). In sheep, a high level of resistance was observed in E. coli against nalidixic acid (MR 87.5%, IQR 81.3-93.8%). In goats, the low level of sensibility was noted in S. aureus against streptomycin (MR 86.8%, IQR 19.4-99.0%). The study provides valuable information on HPCIAs resistance in livestock production in Africa and highlights the need for further research and policies to address the public health risk of AMR. This will likely require an investment in diagnostic infrastructure across the continent. Awareness on the harmful impact of AMR in African countries is a requirement to produce more effective and sustainable measures to curb AMR.

Antimicrobial Use in Pig Farms in the Midwestern Region of Minas Gerais, Brazil

The use of antimicrobials in swine production is an issue that concerns the whole world due to their impact on animal and public health. This study aimed to verify the antimicrobial use in 29 commercial full-cycle farms in the midwestern region of the state of Minas Gerais, since this region is a hub of intensive pig farming in Brazil, as well as the possible correlations between the use of antimicrobials, biosecurity, and productivity. A total of 28 different drugs used for preventive purposes were described. On average, the herds used seven drugs, exposing the piglets for 116 days and totaling 434.17 mg of antimicrobials per kilogram of pig produced. Just eight active ingredients made up 77.5% of the total number of drugs used on the studied herds. Significant differences were found between the variables, biosecurity score and number of sows, antimicrobial amount and number of drugs, number of drugs and number of sows, and between productivity and biosecurity scores. The use of antimicrobials was considered excessive in the swine farms in the state of Minas Gerais compared to what was reported in Brazil and in other countries. Educational measures and better control should be proposed to reduce the preventive use of antimicrobials.

Effects of ciprofloxacin on biogas production and microbial community composition in anaerobic digestion of swine wastewater in ASBR type reactor

In swine farming, antibiotics are often used to reduce disease and promote animal growth. Part of these compounds is not absorbed by the swine body, being excreted and later reaching the treatment systems, soil, and nearby waterbodies. This research sought to investigate the influence of adding ciprofloxacin (CIP) on the anaerobic digestion of swine wastewater. For that, a bench-scale anaerobic sequential batch reactor (ASBR) was used, with 5 L of working volume in six different phases, with volumetric organic loading rate (VOLR) and CIP dosage variation. According to the results, the optimal VOLR for the reactor was 0.60 ± 0.11 gSV L-1 d-1, resulting in biogas productivity of 0.51 ± 0.03 Lbiogas L-1 d-1. After initial stability, adding substrate with 0.5 mgCIP L-1 resulted in an abrupt drop of 82% in the productivity from the 7th to 11th day of addition, coinciding with volatile acids accumulation. Afterward, the reactor recovered and reached apparent stability, with productivity similar to the previous step without the drug. For 2.5 mgCIP L-1 in the substrate, the biogas productivity at equilibrium was 11.8% lower than in the phases with the same VOLR and 0.0 and 0.5 mgCIP L-1. Organic matter removals near 80% were achieved for both dosages. The 16S rRNA metagenomic analyses showed an increase in the relative abundance of most of the phyla found, indicating that the dosages used allowed the acclimatization of microorganisms and possibly the compound biodegradation.

Prevalence and characteristics of ESBL-producing Escherichia coli in clinically healthy pigs: implications for antibiotic resistance spread in livestock

AIM

This study aimed to compare and characterize the resistance profile and the presence of extended-spectrum beta-lactamase (ESBL) related genes in Escherichia coli isolated from healthy finishing pigs fed with or without antibiotics in their diets.

METHODS AND RESULTS

A total of 27 ceftiofur-resistant E. coli isolates were obtained from 96 healthy pigs. The antibiotic resistance profile was tested, and all 27 isolates were classified as multidrug-resistant (MDR). A high proportion of isolates were resistant to cephalosporins, ampicillin, ciprofloxacin, and tetracyclines. The ESBL production was observed in 85% of isolates by double-disc synergy test. The MDR-E. coli isolates harbored ESBL genes, such as blaTEM, blaCTX-M-1, blaCTX-M-2, and blaCTX-M-8,25. In addition, other antibiotics resistance genes (ARGs) were also detected, such as sul2, ant(3″)-I, tetA, and mcr-1. The mobilization of the blaCTX-M gene was confirmed for nine E. coli isolates by conjugation assays. The presence of blaCTX-M on mobile genetic elements in these isolates was demonstrated by Southern blot hybridization, and the resistance to cephalosporins was confirmed in the transconjugants. Our results indicate the prevalence of CTX-M-producing E. coli strains harboring mobile genetic elements in the normal microbiota of healthy pigs.

CONCLUSIONS

These findings highlight the significance of ESBL genes as a global health concern in livestock and the potential spread of antimicrobial resistance to other members of the gastrointestinal tract microbiota.

Biosecurity practices in the dairy farms of southern Brazil

Biosecurity refers to a set of practices that prevents and/or controls the introduction, spread, and elimination of harmful biological agents in a production system. In this study, we aimed to survey the biosecurity practices and determine their correlation with the size of production systems. A biosecurity assessment form was provided to 69 farms in the Campos Gerais region of Paraná, Brazil. The questionnaire was divided into two sections: general and bovine viral diarrhea virus- and bovine herpesvirus type-1-specific sections. The general section covered topics on traffic control, quarantine and animal isolation, hygiene practices, carcass disposal, and disease monitoring/control. The specific section consisted of questions on the reproductive and respiratory factors, use of antimicrobials, and vaccination schedule. The 69 farms were also classified into small (≤ 61), medium (62-201), and large (≥ 202) size farms based on the number of lactating cows. Moreover, multiple correspondence analysis (MCA) was performed between the biosecurity measures and farm size. The main risk factors and variability were related to the traffic control of people, animals, and vehicles/equipment, animal quarantine/isolation, and hygiene practices. MCA revealed that the small farms exhibited a lack of biosecurity measures, including those related to traffic control, animal quarantine, and hygiene. In medium-size farms, contact between bovine animals of different ages and difficulty in animal isolation in the quarantine system were among the main risk factors. In contrast, isolation of sick animals was easy, but the need to frequently purchase cattle was an important risk factor in large farms. These results highlight the relationship between biosecurity measures and farm size, providing valuable insights for the development of better biosecurity plans for production systems.

Concerns about the use of antimicrobials in swine herds and alternative trends

Pig productivity in Brazil has advanced a lot in recent decades. Specialized breeds are more vulnerable to pathogens, which has boosted the use of antimicrobials by farmers. The selective pressure generated favors the emergence of resistant bacteria, which compromises the effectiveness of this treatment and limits therapeutic options. In addition to increasing costs and mortality rates in the production system, public awareness of this issue has increased. The authorities have imposed restrictive measures to control the use of antimicrobials and have banned their use as growth promoters. This literature review highlights biosecurity and animal welfare to prevent pig diseases. Hence, we describe alternatives to the use of antimicrobials in pig production for the selection of effective non-antibiotic feed additives that help maintain good health and help the pig resist disease when infection occurs.

Characterization of Escherichia coli Isolated from Sows Presenting Purulent Vulvar Discharge

Purulent vulvar discharge is a clinical sign of genitourinary tract infections, which are a significant concern in swine facilities, leading to sow culling and mortality. Escherichia coli is one of the main agents involved in these diseases. This study aimed to characterize the virulence and antimicrobial resistance profiles as well as the phylotype of Escherichia coli strains isolated from sows with purulent vulvar discharge. The results showed that at least 2 of the 29 tested virulence genes related to extraintestinal pathogenic E. coli were present in all strains tested. The most frequent gene was iutA, present in all strains, followed by the genes iucD, csgA, iss2, and irp2. Associations between iron uptake genes, genes related to adhesion, attachment, and serum resistance, as well as genes related to toxin release and bacteriocin, were frequent. The most prevalent phylotype was B1 (40.0%), followed by A (18.5%), D (11.9%), C (9.6%), B2 (7.4%), E (4.4%), F (1.5%), and Clade I (0.7%), with B2 being related to highly virulent traits. The strains presented elevated resistance to antimicrobials such as ciprofloxacin, streptomycin, cephalexin, florfenicol, and ampicillin. More than 90% of the strains were identified as multidrug-resistant, indicating the selection that is induced by the high use of antimicrobials in swine farming.

Brazilian Clinical Strains of Actinobacillus pleuropneumoniae and Pasteurella multocida: Capsular Diversity, Antimicrobial Susceptibility (In Vitro) and Proof of Concept for Prevention of Natural Colonization by Multi-Doses Protocol of Tildipirosin

One hundred Actinobacillus pleuropneumoniae (App) and sixty Pasteurella multocida subsp. multocida serogroup A (PmA) isolates were recovered from porcine pneumonic lungs collected from eight central or southern states of Brazil between 2014 and 2018 (App) or between 2017 and 2021 (PmA). A. pleuropneumoniae clinical isolates were typed by multiplex PCR and the most prevalent serovars were 8, 7 and 5 (43, 25% and 18%, respectively). In addition, three virulence genes were assessed in P. multocida isolates, all being positive to capA (PmA) and kmt1 genes, all negative to capD and toxA, and most of them (85%) negative to pfhA gene. The susceptibility of both pathogens to tildipirosin was investigated using a broth microdilution assay. The percentage of isolates susceptible to tildipirosin was 95% for App and 73.3% for PmA. The MIC50 values were 0.25 and 1 μg/mL and the MIC90 values were 4 and >64 μg/mL for App and PmA, respectively. Finally, a multiple-dose protocol of tildipirosin was tested in suckling piglets on a farm endemic for both pathogens. Tildipirosin was able to prevent the natural colonization of the tonsils by App and PmA and significantly (p < 0.0001) reduced the burden of Glaesserella parasuis in this tissue. In summary, our results demonstrate that: (i) tildipirosin can be included in the list of antibiotics to control outbreaks of lung disease caused by App regardless of the capsular type, and (ii) in the case of clinical strains of App and PmA that are sensitive to tildipirosin based on susceptibility testing, the use of this antibiotic in eradication programs for A. pleuropneumoniae and P. multocida can be strongly recommended.

Can Improved Farm Biosecurity Reduce the Need for Antimicrobials in Food Animals? A Scoping Review

Limited and judicious antimicrobial usage (AMU) is considered the key to saving the success of human and veterinary medicine in treating infections. With the limited alternatives for antimicrobials, farm biosecurity (and herd management) is considered a promising tool to mitigate the non-judicious AMU and to maintain animal health, production, and welfare. The present scoping review aims to analyse the effect of farm biosecurity on AMU in livestock systems and formulate recommendations. Peer-reviewed manuscripts published between 2001-2022 were analyzed using the PRISMA framework using PubMed, Scopus, and Science Direct databases. After applying the inclusion criteria, 27 studies were found to assess the effect of farm biosecurity (or management practices) on AMU at the herd/farm level in quantitative/semi-quantitative terms. These studies were carried out in 16 countries, of which 74.1% (20/27) were from 11 European countries. The highest number of studies were from pig farms [51.8% (14/27)], followed by poultry (chicken) farms [25.9% (7/27)], cattle farms [11.1% (3/27)], and a single study from a turkey farm. Two studies include both pig and poultry farms. Most of the studies were cross-sectional [70.4% (19/27)], seven were longitudinal, and one was a case-control study. Complex interactions were observed among factors influencing AMU, such as biosecurity measures, farm characteristics, farmers' attitudes, availability of animal health services, stewardship, etc. A positive association between farm biosecurity and reduction in AMU was observed in 51.8% (14/27) of the studies, and 18.5% (5/27) showed that improvement in farm management practices was associated with a reduction in AMU. Two studies highlighted that coaching and awareness among farmers might lead to a decrease in AMU. A single study on economic assessment concluded biosecurity practices as a cost-effective way to reduce AMU. On the other hand, five studies showed an uncertain or spurious association between farm biosecurity and AMU. We recommend the reinforcement of the concept of farm biosecurity, especially in lower- and middle-income countries (LMICs). Further, there is a need to strengthen the evidence on the association between farm biosecurity and AMU in region- and species-specific farm settings.

Global trends in antimicrobial use in food-producing animals: 2020 to 2030

Use of antimicrobials in farming has enabled the growth of intensive animal production and helped in meeting the global increase in demand for animal protein. However, the widespread use of veterinary antimicrobials drives antimicrobial resistance, with important consequences for animal health, and potentially human health. Global monitoring of antimicrobial use is essential: first, to track progress in reducing the reliance of farming on antimicrobials. Second, to identify countries where antimicrobial-stewardship efforts should be targeted to curb antimicrobial resistance. Data on usage of antimicrobials in food animals were collected from 42 countries. Multivariate regression models were used in combination with projections of animal counts for cattle, sheep, chicken, and pigs from the Food and Agriculture Organization to estimate global antimicrobial usage of veterinary antimicrobials in 2020 and 2030. Maps of animal densities were used to identify geographic hotspots of antimicrobial use. In each country, estimates of antimicrobial use (tonnes) were calibrated to match continental-level reports of antimicrobial use intensity (milligrams per kilogram of animal) from the World Organization for Animal Health, as well as country-level reports of antimicrobial use from countries that made this information publicly available. Globally, antimicrobial usage was estimated at 99,502 tonnes (95% CI 68,535-198,052) in 2020 and is projected, based on current trends, to increase by 8.0% to 107,472 tonnes (95% CI: 75,927-202,661) by 2030. Hotspots of antimicrobial use were overwhelmingly in Asia (67%), while <1% were in Africa. Findings indicate higher global antimicrobial usage in 2030 compared to prior projections that used data from 2017; this is likely associated with an upward revision of antimicrobial use in Asia/Oceania (~6,000 tonnes) and the Americas (~4,000 tonnes). National-level reporting of antimicrobial use should be encouraged to better evaluate the impact of national policies on antimicrobial use levels.

Serotyping and Antimicrobial Susceptibility Profiling of Glaesserella parasuis Isolated from Diseased Swine in Brazil

Glaesserella parasuis is one of the major pathogens in swine intensive production systems. To date, 15 serovars have been described, and the prevalence of these serotypes in different geographical regions has been identified by several methods. G. parasuis outbreaks could be controlled with vaccination if it were not for serovar diversity and limited cross-serovar protection; consequently, antibiotic therapy continues to be necessary for infection control. Here, we present the isolation, identification, serotyping, and antibiotic susceptibility profiling of G. parasuis from diseased swine in Brazil. A total of 105 G. parasuis strains, originating from nine different Brazilian states, were evaluated, and serotypes 4 and 5 were found to be the most prevalent (27.6% and 24.8% respectively). Aminoglycosides, florfenicol, tiamulin, and β-lactams were tested, and they presented lower resistant rates against G. parasuis strains. The highest resistance rates were observed against tylosin (97.1%), sulfadimethoxine (89.5%), danofloxacin (80%), trimethoprim/sulfamethoxazole (62.5%), enrofloxacin (54.3%), and clindamycin (50.5%). Multidrug resistance was detected in 89.5% of tested strains, and a total of sixty resistance profiles were identified. The cluster analysis of resistance patterns showed no correlation with the isolation year or G. parasuis serotype.

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.

Characterization of Salmonella enterica Contamination in Pork and Poultry Meat from São Paulo/Brazil: Serotypes, Genotypes and Antimicrobial Resistance Profiles

Salmonellosis is a zoonosis of major relevance to global public health. Here we present the assessment of Salmonella enterica contamination in pork and poultry meat sold at retail markets in São Paulo, Brazil. A total of 780 meat samples (386 poultry meat and 394 pork samples) were collected from 132 markets. From these, 57 samples (7.3%) were positive for S. enterica isolation, including 32 (8.3%) poultry meat and 25 (6.3%) pork samples. S. enterica isolates were further characterized for serotyping, antimicrobial resistance and genotyping by amplified fragment length polymorphism and pulsed field gel electrophoresis. Antimicrobial resistance analysis demonstrated two main profiles: pork isolates were more resistant to macrolides, β-lactams, tetracycline, phenicols, and fluoroquinolones, and poultry meat isolates presented higher resistance to fluoroquinolones, sulfonamides, tetracycline, and β-lactams. A total of 72.4% of poultry meat isolates were identified as S. Heidelberg, while most of pork isolates were S. Typhimurium (31.7%) and S. Give (16.7%). Genotyping resulted in most clusters consisting exclusively of pork or poultry meat, no cross-contamination was detected, and a tendency to differentiate isolates according to their serotypes and markets of origin. High resistance rates to critically important antimicrobials reinforce the importance of controlling Salmonella contamination in meat production chains.

Antimicrobial usage in Swiss fattening pig farms: is there still potential for improvement?

OBJECTIVE

The aim of this study was to analyze antimicrobial usage (AMU) in fattening pig farms that took part in the SuisSano/Safety + Health Programme in Switzerland over the year 2020 and to discuss the potential for further improvement. Usage was examined according to the antimicrobial's class and indication for use, with emphasis on highest priority critically important antimicrobials (HPCIAs).

METHODS

Data on AMU from 1411 farms, reported in an electronic treatment journal, was used. AMU was quantified through treatment incidence (TI) based on Swiss Defined Daily Doses (DDDch). Indication of use for each antimicrobial class was analyzed with particular focus on HPCIAs.

RESULTS

The total TI of all antimicrobials used in the farms corresponds to 8.9 DDDch per 1000 pig-days at risk, of which HPCIAs represented 2.6 %. A total of 140 farms (9.9 %) partake in HPCIAs usage, with tylosin (73.8 % of total HPCIA TI) and colistin (22.8 % of total HPCIA TI) being the most frequently antimicrobials used. The most common indication for treatment with HPCIAs was gastrointestinal disorders (62.1 % of total HPCIA TI).

CONCLUSION AND CLINICAL RELEVANCE

This study shows that the efforts made in recent years to foster prudent use of antimicrobials and, especially HPCIAs in Swiss pig production, have been successful. Indeed, 90.1 % (1271 of 1411) of the farms did not use any HPCIAs over the year 2020. Of the recorded treatments, HPCIA's represented only 2.6 % of the total TIs used in fattening pigs. Since many farms do not use any HPCIAs, knowledge can be obtained from these farms to identify practices which can further reduce or even stop HPCIAs usage. Moreover, information concerning indications for HPCIAs usage provide input concerning where treatment options other than HPCIAs should be explored by both farmers and veterinarians.

Antimicrobial Resistance Profile of Staphylococcus hyicus Strains Isolated from Brazilian Swine Herds

Staphylococcus hyicus is the causative agent of porcine exudative epidermitis. This disorder affects animals in all producing countries and presents a widespread occurrence in Brazil. This study evaluated strains from a historical collection in order to detect the presence of exfoliative-toxin-encoding genes (SHETB, ExhA, ExhB, ExhC, ExhD), characterize the strains using PFGE, and determine their respective antimicrobial resistance profiles. The results obtained from the evaluation of 77 strains from 1982 to 1987 and 103 strains from 2012 reveal a significant change in resistance profiles between the two periods, especially regarding the antimicrobial classes of fluoroquinolones, amphenicols, lincosamides, and pleuromutilins. The levels of multidrug resistance observed in 2012 were significantly higher than those detected in the 1980s. It was not possible to correlate the resistance profiles and presence of genes encoding toxins with the groups obtained via PFGE. Only 10.5% of the strains were negative for exfoliative toxins, and different combinations of toxins genes were identified. The changes observed in the resistance pattern of this bacterial species over the 30-year period analyzed indicate that S. hyicus could be a useful indicator in resistance monitoring programs in swine production. In a country with animal protein production such as Brazil, the results of this study reinforce the need to establish consistent monitoring programs of antimicrobial resistance in animals, as already implemented in various countries of the world.

Linking Animal Welfare and Antibiotic Use in Pig Farming-A Review

Preventative measures, such as biosecurity and vaccinations, are essential but not sufficient to ensure high standards of health in pig production systems. Restrictive, barren housing and many widely used management practices that cause pain and stress predispose high-performance pigs reared in intensive systems to disease. In this context, antibiotics are used as part of the infrastructure that sustains health and high levels of production in pig farms. Antimicrobial resistance (AMR) is a global emergency affecting human and animal health, and the use of antibiotics (AMU) in intensive livestock farming is considered an important risk factor for the emergence and spread of resistant bacteria from animals to humans. Tackling the issue of AMR demands profound changes in AMU, e.g., reducing their use for prophylaxis and ending it for growth promotion. In support of such recommendations, we revise the link between animal welfare and AMU and argue that it is crucial to sustainably reduce AMU while ensuring that pigs can live happy lives. In support of such recommendations, we aimed to revise the link between animal welfare and AMU in pigs by analysing stress factors related to housing and management and their impact on pig welfare. In particular, we reviewed critical management practices that increase stress and, therefore, pigs' susceptibility to disease and reduce the quality of life of pigs. We also reviewed some alternatives that can be adopted in pig farms to improve animal welfare and that go beyond the reduction in stress. By minimising environmental and management stressors, pigs can become more immunocompetent and prepared to overcome pathogenic challenges. This outcome can contribute to reducing AMU and the risk of AMR while simultaneously improving the quality of life of pigs and, ultimately, maintaining the pig industry's social license.