Antimicrobial use and antimicrobial resistance monitoring in pig production in the United States of America.

Monitoring antimicrobial use (AMU) and antimicrobial resistance (AMR) on farms is recognised as an important component of antimicrobial stewardship, yet the process can be resource intensive. This paper describes a subset of findings from the first year of a collaboration across government, academia and a private sector veterinary practice focused on swine production in the Midwestern United States. The work is supported by participating farmers and the greater swine industry. Twice-annual collection of samples from pigs along with AMU monitoring occurred on 138 swine farms. Detection and resistance of Escherichia coli from pig tissues was assessed, and associations between AMU and AMR were evaluated. This paper describes the methods utilised and the first-year E. coli-related results from this project. Higher minimum inhibitory concentrations (MIC) for enrofloxacin and danofloxacin in E. coli from swine tissues were associated with the purchase of fluoroquinolones. There were no other significant associations between MIC and AMU combinations in E. coli isolated from pig tissues. This project represents one of the first attempts to monitor AMU as well as AMR in E. coli in a large-scale commercial swine system in the United States of America.

Alors même que la surveillance exercée sur l'utilisation des agents antimicrobiens (UAM) et sur la résistance aux agents antimicrobiens (RAM) dans les élevages est une composante majeure reconnue de la gestion des antimicrobiens, le processus en lui-même exige une mobilisation intensive de ressources. Les auteurs décrivent un sous-ensemble de résultats obtenus au cours de la première année d'une collaboration entre les pouvoirs publics, les universités et une clinique vétérinaire privée, axée sur la production porcine dans le Midwest des états-Unis d'Amérique. Ce travail est soutenu par les éleveurs participants et par le secteur porcin au sens large. Une collecte d'échantillons porcins a été effectuée deux fois par an, parallèlement à la surveillance de l'UAM dans 138 élevages. Il a été procédé à une recherche des Escherichia coli présents dans les tissus porcins prélevés puis à la détermination de la résistance aux antimicrobiens chez les microorganismes détectés ; les corrélations éventuelles entre l'UAM et la RAM ont ensuite été évaluées. Les auteurs décrivent les méthodes utilisées dans la cadre de ce projet ainsi que les résultats en lien avec les E. coli obtenus au cours de la première année. Une corrélation a été constatée entre l'augmentation des concentrations minimales inhibitrices (CMI) recueillies pour l'enrofloxacine et la danofloxacine vis-à-vis d'E. coli dans les tissus porcins analysés, d'une part, et l'achat de fluoroquinolones, d'autre part. Aucune autre corrélation significative n'a été décelée entre les CMI recueillies et les profils d'UAM concernant les E. coli isolés à partir des tissus porcins. Ce projet représente l'une des premières tentatives conduites aux états-Unis d'Amérique pour surveiller parallèlement l'UAM et la RAM chez les E. coli dans un système commercial de production porcine à grande échelle.

Aunque se tiene por sabido que la vigilancia en las explotaciones del uso de agentes antimicrobianos (UAM) y de la resistencia a los antimicrobianos (RAM) es un importante componente de la gestión de estos fármacos, no es menos cierto que el proceso puede consumir cuantiosos recursos. Los autores exponen un ubconjunto de observaciones realizadas durante el primer año de un proyecto de colaboración entre la administración pública, el mundo universitario y una clínica veterinaria privada que tenía por objeto de estudio la producción porcina en la zona del medio oeste de los Estados Unidos de América. Respaldaban el proyecto los productores que participaban en él y el sector de la industria porcina en general. Dos veces al año se obtuvieron muestras en 138 explotaciones porcinas, en las que también se seguía de cerca el UAM. Tras realizar pruebas de detección de Escherichia coli en tejidos porcinos y analizar la resistencia de esos microorganismos a antimicrobianos, se buscaron correlaciones entre el uso de estos fármacos y la presencia de eventuales resistencias. Los autores describen los métodos empleados y los resultados obtenidos el primer año del proyecto en relación con E. coli. Se observó una correlación entre la compra de fluoroquinolonas y el aumento de la concentración inhibitoria mínima (MIC) de enrofloxacina y de danofloxacina en los E. coli analizados. No se constató ninguna otra asociación significativa entre las MIC y el uso de diferentes antimicrobianos en los E. coli aislados a partir de tejido porcino. Este proyecto constituye una de las primeras tentativas de hacer seguimiento y balance del uso de agentes antimicrobianos y de la resistencia de E. coli a estos fármacos en el sistema de producción porcina industrial de los Estados Unidos de América.

One Health and antimicrobial resistance, a United States perspective.

Antimicrobial drugs are a precious resource, responsible for saving millions of lives since their discovery. Unfortunately, some antimicrobials are rapidly losing their effectiveness due to the development and spread of antimicrobial resistance (AMR), a multi-faceted and complex problem affecting humans, animals, plants and the environment. While AMR is a global problem, in this paper, the authors briefly highlight some ongoing efforts in the United States of America aimed at integrating a One Health approach into policies and programmes that address this important health threat.

Les antibiotiques sont des ressources de grande valeur qui ont sauvé des millions de vies depuis leur découverte. Malheureusement, certains agents antimicrobiens perdent rapidement leur efficacité en raison de l'apparition et propagation des résistances à ces agents, phénomène complexe et multidimensionnel qui affecte l'homme, les animaux, les plantes et l'environnement. La résistance aux agents antimicrobiens est un problème mondial ; dans cet article, les auteurs décrivent certaines initiatives actuellement mises en oeuvre aux États-Unis d'Amérique pour intégrer l'approche Une seule santé dans les politiques et les programmes conçus pour lutter contre cette menace sanitaire majeure.

Los fármacos antimicrobianos son un recurso valiosísimo, cuyo uso ha salvado millones de vidas desde que fueron descubiertos. Lamentablemente, algunos de ellos están perdiendo rápidamente eficacia debido a la aparición y propagación de resistencias, lo que plantea un problema tan complejo como poliédrico, que afecta a personas, animales, plantas y ecosistemas. Aunque la dimensión del problema es planetaria, los autores destacan aquí brevemente algunas de las iniciativas en curso en los Estados Unidos de América que tienen por objetivo integrar los planteamientos de Una sola salud en el conjunto de políticas y programas desde los cuales se aborda esta importante amenaza sanitaria.

Management of preweaned bull calves on dairy operations in the United States.

Many calves born on dairy farms are male, but little research to date has focused on the management of these calves. The objective of this study was to survey management practices of preweaned dairy bull calves and compare these practices with those used for heifer calves on the same operations. This study was conducted as part of the USDA National Animal Health Monitoring System Dairy 2014 study and included a sample of 42 operations from 10 states. On average, 2.4% of bull calves died before leaving the operation, with most operations selling bull calves before weaning (97.6%). Bull calves left the operation at an average age of 7.6 d (median = 4 d). Producers reported that 96.3% of bull calves received colostrum. Of bulls that were fed colostrum, the vast majority (95.4%) were hand-fed; the remaining calves received colostrum via a combination of hand-feeding and suckling (3.1%) or by suckling only (1.5%). In contrast, all heifer calves on those operations were only hand-fed colostrum. On average, bull calves received 3.1 L of colostrum at their first feeding at 4.3 h after birth compared with 2.9 L at 2.9 h after birth for heifer calves. In the first 24 h, bull and heifer calves received 4.8 and 5.5 L of colostrum, respectively. Only 21.4% of operations dehorned bull calves; in comparison, heifer calves were dehorned on 90.5% of operations. Few operations used analgesics or anesthetics when dehorning bull calves, whereas 28.9% of operations used anesthetics or analgesics when dehorning heifer calves. Overall, 27.8% of operations castrated bull calves. Of the operations that did castrate bulls, 70.0% used a band at an average age of 6.3 wk; the remaining 30% of operations used a knife at 14.7 wk of age on average. Few operations used analgesics or anesthetics when castrating. These results illustrate differences in the care of bull and heifer calves and suggest the need to improve education regarding recommended colostrum feeding and pain management practices in all calves regardless of sex.

Preweaned heifer management on US dairy operations: Part IV. Factors associated with the presence of Escherichia coli O157 in preweaned dairy heifers.

Dairy calves shed pathogenic Escherichia coli O157 (O157) in feces and are a potential route of exposure for human infections. As part of the National Animal Health Monitoring System's (NAHMS) Dairy 2014 study, we evaluated farm, animal, and environmental factors associated with O157 presence in dairy heifer calves. For this O157 study, calves were enrolled from 100 dairy operations in 13 states. Each operation collected data from calves from birth to weaning over an 18-mo period. A single fecal sample was collected from 487 calves in western states and from 871 calves in eastern states (n = 1,358 total), and O157 was detected in 2.5% (n = 34) of fecal samples. Descriptive statistics and univariable screening were used to determine which farm practices, environmental factors, and calf health measures were associated with O157 detection. Multilevel logistic models, controlling for dairy operation, were created using backward elimination of screened variables. The final O157 main effects model included variables for source of colostrum, temperature-humidity index (THI), and serum IgG concentration. Higher serum IgG was associated with lower odds of O157 shedding, whereas calves fed colostrum from their own dam had higher odds of O157 shedding than calves fed colostrum from pooled sources. Interaction models showed that THI level modified the effect of colostrum source on O157 shedding; calves with a THI indicative of heat stress had a significantly increased presence of O157 when fed colostrum from a first-lactation dam. The THI level also modified the effects of serum IgG. Calves with thermoneutral or heat stress THI values had increased presence of O157 with poor (<10 g/L) or adequate (10-15 g/L) serum IgG levels compared with those having excellent (≥15 g/L) serum IgG levels. These results highlight factors that influence the presence of O157 in preweaned dairy heifer calves and may be used to guide practices that mitigate shedding through improved animal husbandry.

Preweaned heifer management on US dairy operations: Part II. Factors associated with colostrum quality and passive transfer status of dairy heifer calves.

Passive transfer of immunity is essential for the short- and long-term health of dairy calves. The objective of this study was to evaluate factors associated with colostrum quality and passive transfer status of US heifer calves. This study included 104 operations in 13 states that participated in the calf component of the National Animal Health Monitoring System's Dairy 2014 study. This 18-mo longitudinal study included 1,972 Holstein heifer calves from birth to weaning. Multivariable mixed linear regression models were selected using backward elimination model selection after univariate screening to determine which factors were associated with colostrum IgG and serum IgG concentrations. The mean colostrum IgG concentration was 74.4 g/L with 77.4% of colostrum samples having IgG concentrations >50 g/L. The final model for colostrum IgG included colostrum source and a categorized temperature-humidity index value (cTHI) for the month before calving. Mean colostrum IgG concentrations were highest for dams in third and higher lactations (84.7 g/L) and lowest for commercial colostrum replacers (40.3 g/L). Colostrum IgG concentrations were highest for cTHI ≥70 (72.6 g/L) and lowest for cTHI <40 (64.2 g/L). The mean serum IgG concentration was 21.6 g/L, with 73.3% of calves having serum IgG concentrations >15 g/L. The final model for serum IgG concentration included region, heat treatment of colostrum, colostrum source, timing to first feeding, volume of colostrum fed in the first 24 h, age of the calf at blood sampling, and colostrum IgG concentration. Mean serum IgG concentrations were highest for calves that received colostrum from first-lactation dams (25.7 g/L) and lowest for calves fed commercial colostrum replacer (16.6 g/L). Serum IgG concentrations were higher for calves fed heat-treated colostrum (24.4 g/L) than for calves fed untreated colostrum (20.5 g/L). Serum IgG concentration was positively associated with the volume of colostrum fed in the first 24 h and colostrum IgG concentration, and negatively associated with the number of hours from birth to colostrum feeding and age (days) at blood collection. Dairy producers should be encouraged to measure the quality of colostrum before administering it to calves and to measure serum IgG or a proxy such as serum total protein or Brix to evaluate passive immunity and colostrum management programs.

Preweaned heifer management on US dairy operations: Part I. Descriptive characteristics of preweaned heifer raising practices.

The objective of this study was to describe preweaned dairy heifer calf management practices on dairy operations across the United States that were used to analyze factors associated with colostrum quality and passive transfer, Cryptosporidium and Giardia, morbidity and mortality, and average daily gain. This study included 104 dairy operations in 13 states that participated in the National Animal Health Monitoring System's Dairy 2014 calf component study. This 18-mo longitudinal study focused on dairy heifer calves from birth to weaning, and data were collected on 2,545 heifer calves. Descriptive statistics were generated regarding colostrum feeding, preweaning housing, milk feeding and consumption, growth, morbidity and mortality, and weaning practices. The majority of calves enrolled were Holsteins (89.4%). Over half the calves (63.2%) enrolled in the study received the majority of their colostrum via bottle; however, 22.1% of calves from 51.0% of operations received colostrum via suckling from their dams. For all calves, the mean time to the first colostrum feeding was 2.8 h, and the average amount of colostrum at the first feeding was 2.9 L, with 4.5 L provided in the first 24 h. The mean serum IgG of all calves was 21.7 g/L; however, 76.0% of operations had at least 1 calf with failure of passive transfer of immunity with a serum IgG below 10 g/L. The majority of calves in the study were housed individually (86.6%). Nonetheless, 20.2% of operations housed some calves in groups, representing 13.4% of all calves. Approximately one-half of the calves in the study (52.3%) were dehorned or disbudded during the preweaning period, with only 27.8% of these calves receiving analgesics or anesthetics during the procedure. Whole or waste milk was the liquid diet type fed to 40.1% of calves, and milk replacer was fed to 34.8% of calves. A combination of milk and milk replacer was fed to 25.1% of calves. Calves, on average, were fed 2.6 L per feeding and fed 2.6 times/d, resulting in a total of 5.6 L of liquid diet fed per day. The mean average daily gain for all calves enrolled in the study was 0.7 kg/d. Fecal samples were collected and almost all operations had at least 1 calf positive for Cryptosporidium (94.2%) or Giardia (99.0%), and 84.6% of operations had calves that tested positive for both Cryptosporidium and Giardia. Over one-third of calves (38.1%) had at least one morbidity event during the preweaning period and the mortality rate was 5.0%. The mean age at weaning was 65.7 d. This study provides an update on dairy heifer raising practices in the United States.

Preweaned heifer management on US dairy operations: Part V. Factors associated with morbidity and mortality in preweaned dairy heifer calves.

The objective of this study was to evaluate morbidity and mortality in preweaned dairy heifer calves based on different health, feeding, and management practices, as well as environmental factors. This study was conducted as part of the calf component of the National Animal Health Monitoring System's Dairy 2014 study, which included 104 dairy operations in 13 states. The calf component was an 18-mo longitudinal study focused on dairy heifer calves from birth to weaning; data were collected on 2,545 calves. The percentage morbidity for all calves enrolled in the study was 33.9%. Backward elimination model selection was used after univariate screening to determine which management practices and environmental factors significantly affected morbidity and mortality. The final morbidity model included birth weight, serum IgG concentration, ventilation type, and average temperature-humidity index (THI) during the preweaning period. After controlling for other independent variables in the model, calves born at a higher birth weight had a lower predicted risk of morbidity than calves with a lower birth weight. An increase in serum IgG concentration was associated with decreased morbidity. Calves housed in positive- or cross-ventilated systems had a 2.2 times higher odds of developing disease compared with calves housed in natural ventilation systems. Average THI during the preweaning period was inversely correlated with morbidity; as THI increased, the predicted morbidity risk decreased. The percent mortality for all calves enrolled in the study was 5.0%. The final mortality model included birth weight, serum IgG concentration, amount of fat/day in the liquid diet, and morbidity. After controlling for other independent variables in the model, calves born at a higher birth weight had a lower risk of mortality. An increase in serum IgG concentration decreased the risk of mortality. The odds of mortality were 3.1 times higher in calves fed ≤0.15 kg of fat/d in the liquid diet compared with calves fed ≥0.22 kg of fat/d. The odds of mortality were 4.7 times higher in calves that experienced any disease throughout the preweaning period than in calves with no disease. In summary, morbidity and mortality were both associated with birth weight and serum IgG concentration. Additionally, morbidity was associated with ventilation type and average monthly THI, and mortality was associated with amount of fat per day in the liquid diet and morbidity.

Preweaned heifer management on US dairy operations: Part III. Factors associated with Cryptosporidium and Giardia in preweaned dairy heifer calves.

The objective of this study was to evaluate management practices and environmental factors associated with cryptosporidiosis and giardiasis in preweaned heifer calves on US dairy operations. This study was conducted as part of the calf component of the National Animal Health Monitoring System's Dairy 2014 study. The calf component included 104 dairy operations in 13 states and was an 18-mo longitudinal study focused on dairy heifer calves from birth to weaning. Fecal samples were collected from 2,249 calves: 839 calves in the West region (California, Colorado, and Washington) and 1,410 calves in the East region (Iowa, Michigan, Minnesota, Missouri, New York, Ohio, Pennsylvania, Vermont, Virginia, and Wisconsin). Fecal samples were collected only once from calves during the preweaning period. Samples were collected from calves 3 to 66 d of age, with a mean of 22 d. Overall, Cryptosporidium and Giardia were detected in 43.1 and 30.5% of fecal samples, respectively. Backward elimination logistic model selection was used after univariate screening to determine which management practices and environmental factors significantly affected the presence of Cryptosporidium or Giardia. The final Cryptosporidium model included herd size, days of age at fecal collection, and average temperature-humidity index for the month of fecal collection (fTHI). Cryptosporidium was found on a higher percentage of large operations (≥500 cows) than small operations (30 to 99 cows). Younger calves were more likely to have a fecal sample positive for Cryptosporidium than samples from older calves. Fecal samples from calves during the warmer parts of the year (fTHI >70) were more likely to be positive for Cryptosporidium than samples collected in colder months (fTHI <20). The final Giardia model included herd size, days of age at fecal collection, average fTHI, failure of passive transfer status, and average daily gain (kg/d) during the preweaning period. Giardia was isolated more frequently from calves on small operations than on large operations and from calves that were older compared with younger calves. Giardia was more frequently isolated in warmer months. Samples from calves with failure of passive transfer were more likely to have Giardia than calves with adequate passive transfer (>10 g/L IgG). Average daily gain during the preweaning period was lower in calves from which Giardia was isolated. These results highlight the factors associated with the presence of Cryptosporidium and Giardia in preweaned dairy heifer calves.

Preweaned heifer management on US dairy operations: Part VI. Factors associated with average daily gain in preweaned dairy heifer calves.

The study objective was to evaluate average daily gain (ADG) in dairy heifer calves based on health, feeding, management practices, and environmental factors. This study included 102 operations in 13 states that participated in the calf component of the National Animal Health Monitoring System's Dairy 2014 study. This 18-mo longitudinal study included 1,410 Holstein heifer calves monitored from birth to weaning. The mean ADG from birth to final weight was 0.74 kg/d. Backward elimination model selection in Proc Mixed after univariate screening determined factors that significantly affected ADG. The final model included dam lactation number, singleton versus twin birth, bedding type, Giardia and Cryptosporidium fecal shedding, disease events, a categorized average temperature-humidity index for the preweaning period (pTHI), amount of protein in the liquid diet (kg/d), milk pasteurization, direct-fed microbials, and the interaction between milk pasteurization and direct-fed microbials. After controlling for other independent variables in the model, calves born to first-lactation dams gained less (0.60 kg/d) than calves from second- (0.65 kg/d) or third- or greater-lactation (0.64 kg/d) dams. Singleton calves gained 0.07 kg/d more than twins. Calves bedded with sand or no bedding gained less (0.49 kg/d) than calves on all other bedding types. Calves negative for Cryptosporidium or Giardia at the time of sampling gained 0.03 or 0.02 kg/d more, respectively, than calves that were positive for Cryptosporidium or Giardia. Calves with no disease events gained 0.07 kg/d more than calves with one or more disease events. Calves experiencing an average pTHI <50 gained more (0.67 kg/d) than calves experiencing an average pTHI from 50 to 69 (0.62 kg/d), or ≥70 (0.59 kg/d). Within the range of observed kilograms of protein fed per day in the liquid diet, every additional 0.1 kg of protein fed per day equated to 0.02 kg/d of gain. Calves fed milk replacer with a direct-fed microbial gained less (0.44 kg/d) than calves fed milk replacer without a direct-fed microbial (0.60 kg/d) and calves fed pasteurized or unpasteurized milk regardless of direct-fed microbial use. These results highlight the importance of feeding a quantity and quality of a liquid diet to achieve optimal growth, keeping calves free of disease, the type or status of bedding, and mitigating the effects of temperature and humidity on preweaning ADG.