Evaluation of the antimicrobial use in pigs in Japan using dosage-based indicators

Assessment of Antimicrobial Use for Companion Animals in South Korea: Developing Defined Daily Doses and Investigating Veterinarians' Perception of AMR

There are global concerns regarding the transmission of antimicrobial-resistant pathogens from animals to humans. Especially, companion animals are increasingly recognized as a potential source due to their close interactions with people, despite a limited number of reported cases. Although, social demands regarding comprehensive surveillance for antimicrobial resistance (AMR) among companion animals are highlighted, there is a lack of a relevant system in South Korea. In this regard, we conducted preliminary investigation on antimicrobial use (AMU) among small animal clinics, along with veterinary practitioner's knowledge and attitude regarding this issue in South Korea. We collected data on 684,153 antimicrobial prescription visits for canine and feline patients from 2019 to 2022 at 100 veterinary facilities in South Korea, using electronic medical records. To evaluate antimicrobial use (AMU) and facilitate comparisons across institutions and time periods, we developed the Defined Daily Dose for Animals (DDDA) and the Defined Animal Daily Dosages per 1000 Animal-Days (DAPD). In addition, we conducted an online survey of 362 veterinary practitioners, which included questions on their perceptions, attitudes, and practices regarding antimicrobial prescriptions. Simple frequency analyses were performed to examine temporal trends, regional differences and variations by facility size in AMU, and to summarize survey responses. Descriptive analysis using data from 100 veterinary clinics revealed a rising trend in AMU between 2019 and 2022, with higher usage observed in larger clinics and non-capital regions. DDDA values for dogs were generally higher than for cats. Survey results highlighted that, while veterinarians exhibited high awareness of AMR, prescribing practices were significantly influenced by clinical judgments and owner demands, often deviating from established guidelines. The adoption of an electronic veterinary prescription management system (e-Vet) was proposed to enhance antimicrobial stewardship. However, concerns regarding the system's efficiency and administrative burden were prominent. To our best knowledge, this study provided DDDA for companion animals for the first time in South Korea. Although the indicator should be improved with more comprehensive data and expert opinion, our study showed that it enables reasonable situation analysis regarding AMU in companion animals. The identified factors that affect veterinarians' prescription practices can also be used to design an effective strategy for promoting appropriate antimicrobial usage.

Antimicrobial Use in the Animal Sector in Japan from 2011 to 2022

Background/Objectives: Evaluating antimicrobial use (AMU) is essential in the investigation and implementation of antimicrobial resistance (AMR) prevention measures. Here, we examined AMU using an index (mg/kg biomass) that considers the antimicrobial sales volume and livestock biomass in Japan from 2011 to 2022. Methods: Antimicrobial sales volumes were obtained from JVARM data, and biomass data were obtained from reliable statistics. Beef cattle, dairy cattle, pigs, broiler chickens, layer chickens, fish raised in freshwater, and fish raised in seawater were targeted in this study. Results: Tetracycline accounted for 39%, macrolides for 18%, penicillins for 12%, and sulfonamides for 11% of the sales in 2022. The peak antimicrobial sales volume was 847 tons in 2017, and then declined to 766 tons by 2022 with fluctuations in the interim. From the perspective of mg/kg biomass, AMU tended to increase in beef cattle, dairy cattle, and fish raised in seawater, while pigs, broilers, layers, and fish raised in freshwater showed a decreasing trend. In broilers, the decreasing trend that could not be confirmed by sales amount alone was detected using the newly established index. Conclusions: By calculating the mg/kg biomass, it became possible to create an interpretation that is different from that of the simple sales quantity data. We believe that this indicator is stable, transparent, and easily understandable for national monitoring.

Trends in Antimicrobial Usage on Swiss Pig Farms from 2018 to 2021: Based on an Electronic Treatment Journal

(1) Background: The aim of this retrospective observational study was to observe the trends in antimicrobial usage (AMU) from 2018 to 2021 in Swiss pigs based on an electronic treatment journal used nationwide by farmers. Thus, for the first time, standardized, longitudinal comparisons of AMU between the years could be analyzed, as well as the influence of targeted interventions, on farms with higher consumption. (2) Methods: The data was evaluated by different indicators, such as the amount of active ingredient in kilograms, treatment days per farm (ATI) and treatment incidence (TI) based either on animal-defined daily doses (TIADD) or used daily doses (TIUDD). Calculations were performed across the following five age categories: suckling piglets, weaners, fattening pigs, and gestating and lactating sows, and the proportions of antimicrobial classes were evaluated for each age category. (3) Results: The highest amount of the active ingredient was administered to the group of fattening pigs, while the suckling piglets received the lowest amount of the active ingredient. In 2021, there was a significant decrease in active ingredient consumption per pig, but a significant increase in ATI, TIADD and TIUDD compared to 2018. The largest proportion of AMU was attributed to penicillins each year, followed by sulfonamides and tetracyclines. The "Highest Priority Critically Important Antimicrobials" represented a proportion of overall usage, declining from 5.2% in 2018 to 3.1% in 2021, while polypeptides were the most used class of critical antimicrobials. Interventions on high-usage farms showed that some farms decreased their AMU in the following year while others did not. (4) Conclusions: This study reveals a decrease in the overall usage measured in kilograms per pig of antimicrobials in Swiss pigs between 2019 and 2021 through the monitoring of AMU, but, at the same time, there was an increase in treatment days or incidence per farm. Critical antimicrobials can be reduced regardless of the indicator. The significance and quality of interventions should be investigated in future studies.

Characterization of Actinobacillus pleuropneumoniae isolated from pigs in Japan using whole genome sequencing

We conducted whole-genome sequencing to investigate the serotypes, the presence of virulence and antimicrobial resistance genes, and the genetic relationships among isolates of Actinobacillus. pleuropneumoniae derived from diseased pigs. Serotype 2 (71.2%) was the most common, but the prevalence of serotypes 6 (13.6%) and 15 (6.8%) increased. Existing vaccines are considered ineffective on the isolates belonging to serotypes 6 and 15. The phylogenetic tree based on core genome single nucleotide polymorphisms showed that the isolates were clustered by serotype. Of the isolates, 62.5% did not have an antimicrobial resistance gene, including a florfenicol resistance gene, but 32.2% had a tetracycline resistance gene. The antimicrobial resistant phenotype and genotype were almost identical. The plasmid-derived contigs harbored resistance genes of aminoglycosides, tetracyclines, β-lactams, phenicols, or sulfonamides. It has been suggested that isolates with different genetic properties from vaccine strains are circulating; however, antimicrobial resistance may not be widespread.

Use of Antimicrobials by Class in Pigs in Germany-A Longitudinal Description Considering Different International Categorisation Systems

Antimicrobial usage in both human and veterinary medicine is considered one of the main drivers of antimicrobial resistance; its reduction poses a serious challenge. To analyse the associations between usage and resistance, data from monitoring systems and classification of all antimicrobial substances are crucial. In this analysis, we investigated longitudinal data collected between 2013 and 2020 within the Veterinary Consumption of Antibiotics project from pig farms in Germany, including all antimicrobial classes, but focusing on critically important antimicrobials: third- and fourth-generation cephalosporins, fluoroquinolones, macrolides, and polymyxins. Analysing the treatment frequency, we found that a reduction in antimicrobial use in all types of pig production has occurred over time, accompanied by a rising percentage of farms without any usage. The lists of the World Health Organisation, World Organisation for Animal Health, and European Medicine Agency classify different antimicrobial substances as critically important. The vast differences between the respective weighted treatment frequencies allocated to the antimicrobials of main interest reflect the huge impact of the three categorisation systems. We concluded that, with the aim of creating national treatment guidelines supporting veterinarians to make treatment decisions, the list of the European Medicine Agency is the most suitable.

National Monitoring of Veterinary-Dispensed Antimicrobials for Use on Pig Farms in Austria: 2015-2020

Antimicrobial use in livestock production systems is increasingly scrutinised by consumers, stakeholders, and the veterinary profession. In Austria, veterinarians dispensing antimicrobials for use in food-producing animals have been required to report these drugs since 2015. Here, we describe the national monitoring systems and the results obtained for Austrian pig production over a six-year period. Antimicrobial dispensing is described using the mass-based metric, milligrams per population correction unit (mg/PCU) and the dose-based metric, Defined Daily Dose (DDDvet) per year and divided into the European Medicines Agency's prudent use categories. Pig production was divided into breeding units, fattening farms, farrow-to-finish farms, and piglet-rearing systems. Over all six years and all pig production systems, the mean amount of antimicrobials dispensed was 71.6 mg/PCU or 2.2 DDDvet per year. Piglet-rearing systems were found to have the highest levels of antimicrobial dispensing in DDDvet, as well as the largest proportion of Category B antimicrobials, including polymyxins. Although progress has been made in promoting a more prudent use of antimicrobials in veterinary medicine in Austria, further steps need to be taken to proactively improve animal health and prevent disease to reduce the need for antimicrobials, particularly those critically important for human medicine, in the future.

Characterization and antimicrobial resistance of Campylobacter jejuni and Campylobacter coli isolated from chicken and pork

The prevalence and antimicrobial resistance (AMR) profile were investigated in Campylobacter jejuni and Campylobacter coli in chicken and pork in Fukuoka, Japan in 2019. Their AMR profiles were compared with those of C. jejuni and C. coli strains isolated in 2013. A total of 53 chicken and 14 pork samples were collected from different supermarkets in Fukuoka in 2019. Campylobacter spp. were isolated by conventional method and characterized by PCR and MALDI-TOF MS. Among 53 chicken samples tested in 2019, 24.5% and 5.7% were positive for C. jejuni and C. coli, respectively, and three (21.4%) of 14 pork samples were positive for C. coli, but not C. jejuni. From the positive samples, 13 and six strains of C. jejuni and C. coli were isolated, respectively. Antimicrobial susceptibility test against 12 different antimicrobials were performed on 48 isolates (43 C. jejuni and five C. coli) from chicken in 2013 and 19 isolates (13 C. jejuni from chicken, three C. coli from chicken and three C. coli from pork) in 2019 using the disk diffusion method. All the C. jejuni and C. coli isolated in 2013 and 2019 were highly resistant to cefazolin and sulfamethoxazole/trimethoprim. Among the C. jejuni isolates from chickens, 25.6% of 2013 isolates were resistant to nalidixic acid, ciprofloxacin, and levofloxacin, and 7% to ampicillin and minocycline, while 30.8% of the isolates were resistant to minocycline, 23.1% to nalidixic acid, ciprofloxacin, and levofloxacin, and 15.4% to ampicillin in 2019. Among the C. coli isolates, 80% of isolates from chickens in 2013, and 33.3% from chicken and 100% from pork in 2019 were resistant to nalidixic acid, ciprofloxacin, and levofloxacin. The frequency of multi-drug resistant (MDR) C. jejuni and C. coli strains from chickens in 2019 were 30.8% and 33.3%, respectively, which were lower than those isolated in 2013 (37.2% and 100%, respectively). One C. jejuni and two C. coli isolates from 2013 were resistant to six antibiotics. However, two C. jejuni and one C. coli isolate from chickens in 2019 were resistant to seven and five antibiotics, respectively. All the C. coli isolates from pork in 2019 were resistant to five antibiotics. The high frequency of AMR strains in C. coli isolates from pork suggests that appropriate use of antimicrobials is required in swine husbandry.

Evaluation of antimicrobial use in dairy cattle, beef cattle and broilers in Japan using dosage-based indicators

The sales amount of antimicrobials intended for use in dairy cattle, beef cattle and broilers from 2008 to 2019 was evaluated for each antimicrobial class and administration route using dosage-based indicators. Our results revealed that the antimicrobial sales amount sold for use in dairy cattle in 2019 in terms of total weight of active ingredient, the number of defined daily doses (DDDs) (theoretical amount of biomass subjected to antimicrobial treatment in a year) and the number of treatment days (TDs) (theoretical number of days of treatment that an animal is subjected to in a year) calculated using Japanese DDD values (DDDjp values) was 36,751 kg, 8,261,848,000 kg·days and 15.5 days, respectively. Likewise, the antimicrobial sales amount sold for use in beef cattle and broilers in 2019 in terms of these metrics was 33,403 kg, 3,928,248,000 kg·days and 3.61 days, and 69,773 kg, 2,947,848,000 kg·days and 10.66 days, respectively. There was a considerable difference between the number of DDDs calculated using DDDjp values and that calculated using European DDD values (DDDvet values) for antimicrobial products sold for use in dairy and beef cattle. Our results also revealed that the sales amount of some antimicrobials, such as cephalosporins and quinolones represented larger proportions when calculated using dosage-based indicators than when calculated using the weight of active ingredient. Considering that Japanese veterinarians and farmers are more likely to conform to the Japanese dosage recommendations rather than the European ones, these results indicate the need for using dosage-based metrics, in particular metrics based on Japanese dosages rather than European dosages.

Antimicrobial use on 74 Japanese pig farms in 2019: A comparison of Japanese and European defined daily doses in the field

Defined daily doses (DDD) have been established in human medicine to standardize the measurement of treatment in a population. In veterinary medicine, the European Medicine Agency published defined daily dose (DDDvet) values for antimicrobial agents used in food-producing animals in 2016. National defined doses (DDDjp) for antimicrobials used for pigs in Japan have recently been determined. The aim of this study was to compare the results of calculated antimicrobial use in the field using the DDDjp and DDDvet values. Data from 74 pig farms in Japan relative to antimicrobial use in 2019 was collected. The numbers of DDDs (the weight of biomass treated in kg-days) using DDDjp and DDDvet values for each farm and for different antimicrobial classes were compared. Associations between calculated numbers of DDDjp and DDDvet on farm level were investigated. In addition, differences in antimicrobial use were investigated between different production types of farms (farrowing, finishing and farrow-to-finish farms). Using DDDjp and DDDvet values, the aggregated number of DDDs for 74 farms were 4,099,188 and 2,217,085 respectively, with the former being larger by 1.85 times than the latter. The most frequently used antimicrobial class was penicillin regardless of whether DDDjp or DDDvet was used. The absence of DDDvet values for certain antimicrobial agents used in Japan and the differences in the number of DDDjps/PCU and DDDvets/PCU indicated the need for Japanese DDDs. The number of DDDs per kg population correction unit (PCU) per farm tended to be higher in farrowing farms than in farrow-to-finish farms and finishing farms, with no significant difference (P = 0.19).

Establishing defined daily doses (DDDs) for antimicrobial agents used in pigs, cattle and poultry in Japan and comparing them with European DDD values

Monitoring of antimicrobial use is essential in the management of the development and selection of antimicrobial resistance. A variety of indicators has become available to monitor antimicrobial use in human and animal medicine. One of them is an indicator based on defined daily dose (DDD). By using the number of DDDs administered and normalising it by the population at risk of being treated over a defined period, one can estimate the number of treatment days with antimicrobial agents in a population. For veterinary medicine, the European Medicines Agency (EMA) has published the European values of DDD (DDDvet) for food-producing animals. In this study, we defined Japanese defined daily doses for antimicrobial agents (DDDjp) using DDD values that we previously assigned for antimicrobial products approved for use in pigs, cattle and poultry in Japan and compared them with DDDvet values. For the comparison, the quotient of Japanese and European values (QDDD) was calculated and the effect of the administration route and the number of active substances contained in the preparation was investigated. A total of 59 DDDjp values were defined for 43 antimicrobial agents using the data of 276 products approved for use in pigs. Likewise, a total of 55 DDDjp values were defined for 32 antimicrobial agents using the data of 196 products for use in cattle, and a total of 27 DDDjps values were defined for 25 antimicrobial agents using the data of 131 products approved for use in poultry. A comparison was made for 42, 28 and 17 pairs of DDDjp and DDDvet values for antimicrobial agents used for pigs, cattle and poultry respectively. The comparison showed median QDDD value of 0.61 and 0.66 for antimicrobial agents used for pigs and cattle respectively (p<0.01), indicating that the Japanese daily doses are significantly lower than the corresponding EMA values in these species. For the antimicrobial agents used for poultry, no significant difference was observed between DDDjp and DDDvet values with a median QDDD value of 1.15. The difference between DDDvet and DDDjp values and absence of DDDvet values for some antimicrobial agents marketed in Japan indicate that DDDjp rather than DDDvet should be used as the basis for the calculation of antimicrobial use monitoring in farm animals in Japan.