Demand for animal protein is rising globally and has been facilitated by the expansion of intensive farming. However, intensive animal production relies on the regular use of antimicrobials to maintain health and productivity on farms. The routine use of antimicrobials fuels the development of antimicrobial resistance, a growing threat for the health of humans and animals. Monitoring global trends in antimicrobial use is essential to track progress associated with antimicrobial stewardship efforts across regions. We collected antimicrobial sales data for chicken, cattle, and pig systems in 41 countries in 2017 and projected global antimicrobial consumption from 2017 to 2030. We used multivariate regression models and estimated global antimicrobial sales in 2017 at 93,309 tonnes (95% CI: 64,443, 149,886). Globally, sales are expected to rise by 11.5% in 2030 to 104,079 tonnes (95% CI: 69,062, 172,711). All continents are expected to increase their antimicrobial use. Our results show lower global antimicrobial sales in 2030 compared to previous estimates, owing to recent reports of decrease in antimicrobial use, in particular in China, the world’s largest consumer. Countries exporting a large proportion of their production are more likely to report their antimicrobial sales data than countries with small export markets.
The objective of this study was to determine the prevalence of Rhodococcus equi strains resistant to macrolides and rifampin over time in clinical samples from foals submitted to diagnostic laboratories in central Kentucky. We performed a retrospective observational study of all clinical samples from foals that were submitted to veterinary diagnostic laboratories in Kentucky between January 1995 and December 2017. Samples were included if the R. equi bacterium was cultured and tested for in vitro susceptibility to erythromycin or rifampin. In vitro susceptibility testing to erythromycin was available for 2,169 isolates of R. equi, while susceptibility testing to both erythromycin and rifampin was available for 1,681 isolates. Rifampin resistance was first detected in 2000, and erythromycin resistance was first detected in 2004. Between 1995 and 2006, the proportion of resistant isolates of R. equi was 0.7% for erythromycin and 2.3% for rifampin. There was a significant (P Ͻ 0.001) increase in the proportion of resistant R. equi between 2007 and 2017, with 13.6% of isolates being resistant to erythromycin and 16.1% being resistant to rifampin. Between 2007 and 2017, isolates of R. equi resistant to erythromycin or rifampin were significantly less likely to be isolated from feces than from the respiratory tract, other soft tissues, or musculoskeletal infections. The considerable increase in the prevalence of isolates of R. equi resistant to macrolides and rifampin since 2007 is of concern for both human and animal health.
In Thailand, pig production has increased considerably in the last decades to meet a growing demand for pork. Antimicrobials are used routinely in intensive pig production to treat infections and increase productivity. However, the use of antimicrobials also contributes to the rise of antimicrobial resistance with potential consequences for animal and human health. Here, we quantify the association between antimicrobial use and resistance rates in extensive and intensive farms with a focus on geographic proximity between farm and drugstores. Of the 164 enrolled farms, 79% reported using antimicrobials for disease prevention, treatment, or as a feed additive. Antimicrobial-resistant E. coli were present in 63% of farms. These drugs included critically important antimicrobials, such as quinolones and penicillins. Medium-scale farms with intensive animal production practices showed higher resistance rates than small-scale farms with extensive practices. Farms with drug-resistant Escherichia coli were located closer to drugstores and a had a higher proportion of disease than farms without drug-resistant E. coli. We found no association between the presence of resistance in humans and antimicrobial use in pigs. Our findings call for actions to improve herd health to reduce the need for antimicrobials and systematic training of veterinarians and drugstore owners on judicious use of antimicrobials in animals to mitigate resistance.
SUMMARY
The development and spread of antimicrobial resistance are major concerns for human and animal health. The effects of the overuse of antimicrobials in domestic animals on the dissemination of resistant microbes to humans and the environment are of concern worldwide. Rhodococcus equi is an ideal model to illustrate the spread of antimicrobial resistance at the animal-human-environment interface because it is a natural soil saprophyte that is an intracellular zoonotic pathogen that produces severe bronchopneumonia in many animal species and humans. Globally, R. equi is most often recognized as causing severe pneumonia in foals that results in animal suffering and increased production costs for the many horse-breeding farms where the disease occurs. Because highly effective preventive measures for R. equi are lacking, thoracic ultrasonographic screening and antimicrobial chemotherapy of subclinically affected foals have been used for controlling this disease during the last 20 years. The resultant increase in antimicrobial use attributable to this “screen-and-treat” approach at farms where the disease is endemic has likely driven the emergence of multidrug-resistant (MDR) R. equi in foals and their environment. This review summarizes the factors that contributed to the development and spread of MDR R. equi, the molecular epidemiology of the emergence of MDR R. equi, the repercussions of MDR R. equi for veterinary and human medicine, and measures that might mitigate antimicrobial resistance at horse-breeding farms, such as alternative treatments to traditional antibiotics. Knowledge of the emergence and spread of MDR R. equi is of broad importance for understanding how antimicrobial use in domestic animals can impact the health of animals, their environment, and human beings.
I n Canada, foodborne pathogens cause an estimated 4 million cases of human illness, 11,600 hospitalizations, and 238 deaths each year (1). Escherichia coli, Campylobacter, and Salmonella are the foodborne zoonotic pathogens most frequently associated with infections from poultry products (2). Antimicrobial drugs have been used in ovo, feed, or water to pre-
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